CFD-DEM

Imodeli ye- **CFD-DEM**, noma **imodeli ye-Computational Fluid Dynamics / Discrete Element Method**, inqubo esetshenziselwa ukumodela noma ukulingisa amasistimu ahlanganisa uketshezi nezinto eziqinile noma izinhlayiya. Ku-CFD-DEM, ukunyakaza kokuqinile okuqinile noma isigaba sezinhlayiya kutholwa I-Discrete Element Method (DEM) esebenzisa imithetho yokunyakaza ka-Newton kuyo yonke izinhlayiya, kuyilapho ukugeleza koketshezi oluqhubekayo kuchazwa izibalo ezimaphakathi zendawo ze-Navier-Stokes ingaxazululwa kusetshenziswa indlela yendabuko yeComputational Fluid Dynamics (CFD).Ukusebenzisana phakathi kwesigaba soketshezi kanye nesigaba sokuqinile kumodelwa ngokusetshenziswa komthetho wesithathu ka-Newton .

Ukufakwa okuqondile kwe-CFD ku-DEM ukuze kufundwe inqubo ye-gas fluidization kuze kube manje kuzanywe ngu-Tsuji et al.   futhi kamuva nje nguHoomans et al.,  Deb et al.  kanye noPeng et al.  Uhlolojikelele lwakamuva ngezinkambu zezicelo lunikezwe u-Kieckhefen et al. 

## Ukufana
I-OpenMP iboniswe iphumelela kakhulu ekwenzeni izibalo ezihlanganisiwe ze-CFD-DEM kuhlaka olufanayo uma kuqhathaniswa ne- MPI ka-Amritkar et al.  Muva nje, kusungulwe isu elihambisanayo lezilinganiso eziningi  . Ngokuvamile, isizinda sokulingisa sihlukaniswe izizinda eziningi ezingaphansi futhi inqubo ngayinye ibala isizinda esisodwa esingaphansi sisebenzisa ulwazi lomngcele oludlula i-MPI; kusizinda ngasinye esingaphansi, ama-CPU asetshenziselwa ukuxazulula isigaba samanzi kuyilapho inhloso evamile ye-GPU isetshenziselwa ukuxazulula ukunyakaza kwezinhlayiya.Kodwa-ke, kule ndlela yokubala ama-CPU nama-GPU asebenza nge-serial. Okusho ukuthi, ama-CPU awasebenzi ngenkathi ama-GPU ebala izinhlayiya eziqinile, futhi ama-GPU awasebenzi lapho ama-CPU ebala isigaba soketshezi.ukuze kuqhutshekwe kusheshiswe ukubala, i-CPU ne-GPU computing ingagqagqana kusetshenziswa inkumbulo eyabiwe yohlelo lwe-Linux. Ngakho, isigaba samanzi kanye nezinhlayiya zingabalwa ngesikhathi esifanayo.

## Ukunciphisa izindleko zokubala kusetshenziswa i-Coarse Grained Particles
Izindleko zokubala ze-CFD-DEM zinkulu ngenxa yenani elikhulu lezinhlayiya kanye nezinyathelo zesikhathi esincane zokuxazulula ukungqubuzana kwezinhlayiyana. Ukunciphisa izindleko zokubala, izinhlayiya eziningi zangempela zingafakwa ku-Coarse Grained Particle (CGP).   Ububanzi be-CGP bubalwa ngesibalo esilandelayo:

:  d_{CGP} = d_{realParticle} \cdot W^{1/3},

lapho  W  inombolo yezinhlayiya zangempela ku-CGP. Ngemuva kwalokho, ukunyakaza kwama-CGP kungalandelelwa kusetshenziswa i-DEM. Ezifanisweni kusetshenziswa Izinhlayiya Eziqinile Ezivuthiwe, izinhlayiya zangempela ku-CGP zingaphansi kwamandla okudonsa afanayo, izinga lokushisa elifanayo kanye nezinhlayiyana zobuningi bezinhlobo ezifanayo. Umfutho, ukushisa nokudluliswa kwenqwaba phakathi koketshezi nezinhlayiya kubalwa kuqala kusetshenziswa ububanzi bezinhlayiya zangempela bese kukalwa  W  izikhathi. Inani le  W  ihlobene ngokuqondile nezindleko zokubala kanye nokunemba.  Nini  W  ilingana nobunye, ukulingisa kuba yimiphumela yokuzuza esuselwe ku-DEM enokunemba okuphezulu kakhulu okunokwenzeka. Njengoba lesi silinganiso sikhula, isivinini sokulingisa sikhuphuka kakhulu kodwa ukunemba kwakho kuyawohloka.Ngaphandle kokwenyuka kwesivinini, imibandela evamile yokukhetha inani lale pharamitha ayikakatholakali.Kodwa-ke, kumasistimu anezakhiwo ze-mesoscale ezihlukile, njengamabhamuza namaqoqo, usayizi wephasela kufanele ube mncane ngokwanele ukuze uxazulule ukuwohloka, ukuhlanganisa, nokuphuka kwamabhamuza noma amaqoqo. Inqubo yokuhlanganisa izinhlayiya ndawonye inciphisa imvamisa yokushayisana, okuthonya ngokuqondile ukuchithwa kwamandla. Ukulandisa ngaleli phutha, i-coefficient yokubuyisela ephumelelayo yahlongozwa ngu-Lu et al.,  ngokusekelwe kumbono we-kinetic wokugeleza kwe-granular, ngokucabangela ukuchithwa kwamandla ngesikhathi sokushayisana kwesistimu yasekuqaleni kanye nesistimu yezinhlamvu ezimahhadla kuyafana.

:  e_{CGP} = \sqrt{1+\left(e_{realParticle}^2-1\right)W^{1/3}}

## Isoftware
Umthombo ovulekile kanye nesofthiwe engeyona eyentengiso:

* I-CFDEMcoupling iyibhokisi lamathuluzi lomthombo ovulekile lokuhlanganisa i-CFD-DEM. Ithuthukiswe yi- DCS Computing GmbH
* I-MFiX (Iphakheji yokulingisa ukugeleza kwe-Open Source multiphase).

Isoftware Yezohwebo

* I-EDEM (DEM Solutions Ltd.  ) 
* I-Rocky DEM - I-Discrete Element Modelling kanye ne-Particle Simulation Software elingisa ngokushesha nangokunembile ukuziphatha kokugeleza.
* I-Flow 3D - engeza i-DEM kumojuli futhi imodeli ngempumelelo izinkinga ze-CFD-DEM
* U-Ansys Uhlakaniphile
* I-Cradle; https://www.mscsoftware.com/product/cradle-cfd 
* I-Simicenter STAR-CCM+