COMSOL Multiphysics
Release Notes

COMSOL Multiphysics Release Notes© 1998–2022 COMSOL
Protected by patents listed on www.comsol.com/patents, or see Help>About COMSOL Multiphysics on theFile menu in the COMSOL Desktop for less detailed lists of U.S. Patents that may apply. Patents pending.
This Documentation and the Programs described herein are furnished under the COMSOL Software License
Agreement (www.comsol.com/sla) and may be used or copied only under the terms of the license
agreement.
COMSOL, the COMSOL logo, COMSOL Multiphysics, COMSOL Desktop, COMSOL Compiler,
COMSOL Server, and LiveLink are either registered trademarks or trademarks of COMSOL AB. All othertrademarks are the property of their respective owners, and COMSOL AB and its subsidiaries and products
are not affiliated with, endorsed by, sponsored by, or supported by those trademark owners. For a list of suchtrademark owners, see www.comsol.com/trademarks.
Version: COMSOL 6.1

Contact Information
Visit the Contact COMSOL page at www.comsol.com/contact to submit general inquiries
or search for an address and phone number. You can also visit the Worldwide Sales Offices
page at www.comsol.com/contact/offices for address and contact information.
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Part number: CM010001

C o n t e n t s
Chapter 1: Release Notes
COMSOL Multiphysics

10

General New Functionality . . . . . . . . . . . . . . . . . . . 10
New Functionality in the Model Manager . . . . . . . . . . . . . . 10
New Functionality in the Model Manager Server . . . . . . . . . . . 12
New Functionality in the Application Builder . . . . . . . . . . . . 13
New Functionality in COMSOL Compiler™ . . . . . . . . . . . . 17
New and Improved General Functionality in COMSOL Multiphysics . . . 17
New Geometry and Mesh Functionality . . . . . . . . . . . . . . 21
New Functionality in the Physics Interfaces . . . . . . . . . . . . . 23
New and Updated Operators, Functions, and Definitions . . . . . . . 25
New Functionality in Studies and Solvers . . . . . . . . . . . . . . 26
New and Improved Results and Visualization Functionality . . . . . . . 27®
New Java API Methods . . . . . . . . . . . . . . . . . . . . 32
New COMSOL Server Functionality . . . . . . . . . . . . . . . 32
General Backward Compatibility Considerations . . . . . . . . . . . 32
Backward Compatibility with Version 6.0. . . . . . . . . . . . . . 33
Backward Compatibility with Version 5.6. . . . . . . . . . . . . . 35
Backward Compatibility with Version 5.5. . . . . . . . . . . . . . 36
AC/DC Module

37

New Functionality in Version 6.1 . . . . . . . . . . . . . . . . . 37
Updated Functionality in Version 6.1 . . . . . . . . . . . . . . . 40
New and Updated Models in Version 6.1. . . . . . . . . . . . . . 41
Backward Compatibility with Version 6.0 and Earlier . . . . . . . . . 43
Acoustics Module

44

New Functionality in Version 6.1 . . . . . . . . . . . . . . . . . 44
New and Updated Model Examples in 6.1 . . . . . . . . . . . . . 50
Important Fixes in Version 6.1 . . . . . . . . . . . . . . . . . . 51
Backward Compatibility with Version 6.0. . . . . . . . . . . . . . 51

CONTENTS | 3

Battery Design Module

53

New Functionality in Version 6.1 . . . . . . . . . . . . . . . . . 53
New and Updated Applications and Models in Version 6.1 . . . . . . . 56
CAD Import Module, Design Module, and LiveLink™ Products
for CAD57

New Functionality in Version 6.1 . . . . . . . . . . . . . . . . . 57
New Functionality in the Design Module in Version 6.1 . . . . . . . . 58
New Functionality in LiveLink™ for AutoCAD® in Version 6.1 . . . . . 58
New Functionality in LiveLink™ for Inventor® in Version 6.1 . . . . . . 58
New Functionality in LiveLink™ for PTC® Creo® Parametric™ in
Version 6.1. . . . . . . . . . . . . . . . . . . . . . . . 58
New Functionality in LiveLink™ for Revit® in Version 6.1 . . . . . . . 59
New Functionality in LiveLink™ for SOLIDWORKS® in Version 6.1 . . . 59
New Functionality in LiveLink™ for Solid Edge® in Version 6.1 . . . . . 59
CFD Module

60

New Functionality in Version 6.1 . . . . . . . . . . . . . . . . . 60
New and Updated Models in Version 6.1. . . . . . . . . . . . . . 62
Backward Compatibility with Version 6.0 and Earlier . . . . . . . . . 62
Backward Compatibility with Version 5.6 and Earlier . . . . . . . . . 63
Backward Compatibility with Version 5.5 and Earlier . . . . . . . . . 63
Chemical Reaction Engineering Module

64

New Functionality in Version 6.1 . . . . . . . . . . . . . . . . . 64
New Models in Version 6.1 . . . . . . . . . . . . . . . . . . . 67
Updated Models in Version 6.1 . . . . . . . . . . . . . . . . . 68
Composite Materials Module

70

New Functionality in Version 6.1 . . . . . . . . . . . . . . . . . 70
New Models in Version 6.1 . . . . . . . . . . . . . . . . . . . 71
Corrosion Module

72

New Functionality in Version 6.1 . . . . . . . . . . . . . . . . . 72
New and Updated Models in Version 6.1. . . . . . . . . . . . . . 74
ECAD Import Module

75

New Functionality in Version 6.0 . . . . . . . . . . . . . . . . . 75

4 | CONTENTSElectrochemistry Module

76

New Functionality in Version 6.1 . . . . . . . . . . . . . . . . . 76
Electrodeposition Module

78

New Functionality in Version 6.1 . . . . . . . . . . . . . . . . . 78
Fatigue Module

80

New Functionality in Version 6.1 . . . . . . . . . . . . . . . . . 80
Fuel Cell & Electrolyzer Module

81

New Functionality in Version 6.1 . . . . . . . . . . . . . . . . . 81
New and Updated Models in Version 6.1. . . . . . . . . . . . . . 84
Geomechanics Module

85

New Functionality in Version 6.1 . . . . . . . . . . . . . . . . . 85
Heat Transfer Module86

New and Improved Functionality in Version 6.1 . . . . . . . . . . . 86
New Applications in Version 6.1 . . . . . . . . . . . . . . . . . 89
Updated Applications in Version 6.1 . . . . . . . . . . . . . . . 89
Backward Compatibility with Version 6.0. . . . . . . . . . . . . . 90
Backward Compatibility with Version 5.6. . . . . . . . . . . . . . 91
Backward Compatibility with Version 5.5. . . . . . . . . . . . . . 92
Liquid & Gas Properties Module

94

Improved Functionality in Version 6.1 . . . . . . . . . . . . . . . 94
New Model in Version 6.1 . . . . . . . . . . . . . . . . . . . 94
MEMS Module

95

New Functionality in Version 6.1 . . . . . . . . . . . . . . . . . 95
New Models in Version 6.1 . . . . . . . . . . . . . . . . . . . 99
Metal Processing Module

101

New Functionality in Version 6.1 . . . . . . . . . . . . . . . .

101

New Models in Version 6.1 . . . . . . . . . . . . . . . . . .

102

Microfluidics Module

103

New Functionality in Version 6.1 . . . . . . . . . . . . . . . .

103

CONTENTS | 5

6 | CONTENTS

Updated Applications in Version 6.1 . . . . . . . . . . . . . .

103

Backward Compatibility with Version 6.0. . . . . . . . . . . . .

104

Backward Compatibility with Version 5.5 and Earlier . . . . . . . .

104

Molecular Flow Module

105

New Functionality in Version 6.1 . . . . . . . . . . . . . . . .

105

Updated Applications in Version 6.1 . . . . . . . . . . . . . .

105

Backward Compatibility with Version 6.0 and Earlier . . . . . . . .

105

Multibody Dynamics Module106

New Functionality in Version 6.1 . . . . . . . . . . . . . . . .

106

Nonlinear Structural Materials Module

109

New Functionality in Version 6.1 . . . . . . . . . . . . . . . .

109

New Models in Version 6.1 . . . . . . . . . . . . . . . . . .

111

Optimization Module

113

New Functionality in Version 6.1 . . . . . . . . . . . . . . . .

113

New and Updated Models in Version 6.1. . . . . . . . . . . . .

114

Backward Compatibility with Version 6.0. . . . . . . . . . . . .

115

Particle Tracing Module116

New and Improved Functionality in Version 6.1 . . . . . . . . . .

116

New Applications in Version 6.1 . . . . . . . . . . . . . . . .

117

Important Fixes in Version 6.1 . . . . . . . . . . . . . . . . .

117

Backward Compatibility with Version 6.0 and Earlier . . . . . . . .

118

Pipe Flow Module

119

New Functionality in Version 6.1 . . . . . . . . . . . . . . . .

119Updated Models in Version 6.1 . . . . . . . . . . . . . . . .

119

Plasma Module

121

New Functionality in Version 6.1 . . . . . . . . . . . . . . . .

121

New and Updated Applications in Version 6.1 . . . . . . . . . . .

123

Backward Compatibility with Version 6.0 and Earlier . . . . . . . .

124

Backward Compatibility with Version 5.5 and Earlier . . . . . . . .

124

Porous Media Flow Module

125

New Functionality in Version 6.1 . . . . . . . . . . . . . . . .

125

New Models in Version 6.1 . . . . . . . . . . . . . . . . . .

126

Polymer Flow Module

128

New Functionality in Version 6.1 . . . . . . . . . . . . . . . .

128

New Models and Updated Models in Version 6.1. . . . . . . . . .

129

Backward Compatibility with Version 6.0. . . . . . . . . . . . .

129

Ray Optics Module130

New and Improved Functionality in Version 6.1 . . . . . . . . . .

130

New And Updated Applications in Version 6.1 . . . . . . . . . .

131Important Fixes in Version 6.1 . . . . . . . . . . . . . . . . .

131

Backward Compatibility with Version 6.0 and Earlier . . . . . . . .

132

RF Module

133

New Functionality in Version 6.1 . . . . . . . . . . . . . . . .

133

New and Updated Models in Version 6.1. . . . . . . . . . . . .

136

Backward Compatibility with Version 6.0 and Earlier . . . . . . . .

138

Rotordynamics Module

139

New Functionality in Version 6.1 . . . . . . . . . . . . . . . .

139

New Models in Version 6.1 . . . . . . . . . . . . . . . . . .

140

Structural Mechanics Module

141

New Functionality in Version 6.1 . . . . . . . . . . . . . . . .

141

New and Updated Models in Version 6.1. . . . . . . . . . . . .

150

Subsurface Flow Module

153

New Functionality in Version 6.1 . . . . . . . . . . . . . . . .

153

New Models in Version 6.1 . . . . . . . . . . . . . . . . . .

154

Uncertainty Quantification Module

155

New Functionality in Version 6.1 . . . . . . . . . . . . . . . .

155

Wave Optics Module

156

New Functionality in Version 6.1 . . . . . . . . . . . . . . . .

156

New and Updated Models in Version 6.1. . . . . . . . . . . . .

159

CONTENTS | 7

Backward Compatibility with Version 6.0 and Earlier . . . . . . . .

160

Material Library162

New and Updated Material Data in Version 6.1 . . . . . . . . . .

162®
LiveLink™ for Excel

165

New Functionality in Version 6.1 . . . . . . . . . . . . . . . .

165

LiveLink™ for MATLAB®

166

Backward Compatibility with Version 6.0. . . . . . . . . . . . .

167

Backward Compatibility with Version 5.6. . . . . . . . . . . . .

167®
LiveLink™ for Simulink

168

New Functionality in Version 6.1 . . . . . . . . . . . . . . . .

168

General Backward Compatibility . . . . . . . . . . . . . . . .

168

The COMSOL API for Use with Java

8 | CONTENTS

166

New Functionality in Version 6.1 . . . . . . . . . . . . . . . .

®

169

COMSOL 6.1 API Changes . . . . . . . . . . . . . . . . . .

169

COMSOL 6.0 API Changes . . . . . . . . . . . . . . . . . .

170

COMSOL 5.6 API Changes . . . . . . . . . . . . . . . . . .

171

Index

173

1

Release Notes
COMSOL Multiphysics® version 6.1 includes new functionality andimprovements across the COMSOL® products. These Release Notes provide
information regarding new functionality in version 6.1 for all COMSOL® software
products.

9

COMSOL Multiphysics
General New Functionality
INTERFACE TO MICROSOFT WORD
A new interface to Microsoft Word® is now available, providing similar functionality

as the interface to Microsoft PowerPoint®. When you install this interface, a
COMSOL ribbon will be added to Microsoft Word®, which provides functionality forinteractively creating and updating Word documents with content, such as plots andtables, from COMSOL Multiphysics® models.

New Functionality in the Model Manager
Also see the Model Manager Reference Manual for more information.
GENERAL IMPROVEMENTS• Comments for previously saved commits can now be edited.
• Components, geometry sequences, materials, and physics can now be inserted intoa model opened in the COMSOL Desktop using the Insert into Opened Modelbutton in the Contents section of the Settings window for a model version.
• A model can be opened with the current node selected using the Open Node buttonin the Contents section of the Settings window for a model version.
• Date filters now support shorthands for common date intervals. These shorthands
are also supported in the Model Manager search syntax. Examples include@lastModified:TODAY and @lastModified:YESTERDAY.
• The default repository when saving models or data files can now be changed fromthe initial repository. The most recently used repository is also remembered when
opening models or selecting data files.
• The Copy Location option in the context menu of a model version can be used toquickly open the model in another COMSOL Multiphysics process. A new Clipboard
option appears in the list of options in the Open window when such a location has
been copied.
COMPATIBILITY BETWEEN VERSIONS

Local and server databases can be shared between COMSOL Multiphysics 6.0 and
COMSOL Multiphysics 6.1 since both the database format and the server connection

10 |CHAPTER 1: RELEASE NOTES

are designed for backward and forward compatibility. All database configurations in
COMSOL Multiphysics are automatically migrated as part of the preferences
migration when upgrading. Some new Model Manager functionality in COMSOLMultiphysics is only available when connected to the newest version of the ModelManager server.

Secure Credentials Entry When Running in Client–Server Mode
The Model Manager no longer allows writing a password in the Connect to Server
Database window when running COMSOL Multiphysics in client–server mode unlessthe client–server connection is over a secure channel. Instead, the password is provided
via a secure password prompt in the console window for the started COMSOLMultiphysics server process.
DEMO DATABASE FOR MODEL MANAGER

A local demo database for Model Manager can now be downloaded and opened using
the Download Demo Database for Model Manager option in the Help menu. On the
Windows® operating system, this menu is available as a submenu to the File menu. The
demo database contains an imported copy of the COMSOL Application Libraries.
This functionality was released already with COMSOL Multiphysics 6.0 update 2.
VERSION CONTROL OF RELATED FILES AS FILESETSModel Manager now supports storing related data files as filesets in a database. This
enables version control of, for example, CAD assemblies that reference multiple
external component files or HTML documents referencing external image files. The
file contents of a fileset can be viewed and updated via the Settings window in the
Model Manager workspace.

Improved CAD Support
All CAD formats can now be imported to Model Manager databases and used with the
CAD Import Module functionality in Model Builder. When importing a CAD
assembly file to the database, any external component files that the assembly references
are imported as well.

Save Model Output to Databases
Data files generated as output from a model can now be saved directly to a ModelManager database. This includes, for example, export of geometries, meshes, plots,
animations, and reports. The output files are version controlled in the database inexactly the same way as other data files. Model Manager also stores a reference between

COMSOL MULTIPHYSICS|

11

a saved file version and the corresponding model version. These version references areshown in the References window with a new Output File reference type.

Improvements to Tag Assignments and Tag Trees
Several usability improvements have been made to tags:• Assigned tags are now shown in a compact format in the Settings window.
• Tag assignment in the Model Manager workspace now supports selection ofmultiple items.
• A tag can be assigned to the current selection of models and data files when creating
the tag from the New Tag dialog box.
• The tag tree in the Model Manager window now shows all tags when searching in abranch — without having to repeatedly click the Show More toolbar button. Eachtag node shows a count of the number of item hits matching that tag assignment.
• Models and data files shown under tag nodes in tag trees are grouped into batchesof 100 items, with the next batch of items obtained by expanding a Show More node.
• Tags can be assigned to the model that is opened in the COMSOL Desktop alreadyfrom the Save window. New tags can also be created as needed from that window.

New Functionality in the Model Manager Server
Also see the Model Manager Server Manual for more information.
GENERAL IMPROVEMENTS• The Model Manager server is now available for ARM64 architectures on macOSand Linux®.
• A Hyperlink primitive attribute has been added to the asset management system. The
attribute can be used to link to a web resource.
• A File version primitive attribute has been added to the asset management system.
The attribute can be used to link to a file version stored in the database from anasset.
CONNECT WITH CPU AND NSL LICENSES

COMSOL Multiphysics can now connect to a Model Manager server with CPUlocked licenses (CPU) and named single-user licenses (NSL) in addition to floating
network licenses (FNL).
This functionality was released already with COMSOL Multiphysics 6.0 update 2.

12 |CHAPTER 1: RELEASE NOTESSWITCHING BETWEEN DATABASES

The Model Manager server now supports switching between databases in the webinterface via a list in the top menu bar. Selecting a database from the list sets it as thecurrent database shown in the web interface. The list is hidden if only one database isavailable. COMSOL Multiphysics always connects to the database set as the default
database.
WEB-BASED ASSET MANAGEMENT SYSTEM

The Model Manager server now includes a web-based asset management system that
COMSOL Multiphysics users can use to link models and simulation results to various
documents, presentations, project notes, slides, and other supplementary files andmetadata. The asset management system can also be used to share such files andmetadata with coworkers who may not have access to the COMSOL Multiphysics
softwareThis functionality was released already with COMSOL Multiphysics 6.0 update 2.
BUILT-IN SUPPORT FOR HTTPS, EXTERNAL AUTHENTICATION, AND
REVERSE PROXY-BASED AUTHENTICATION

Setting up Transport Layer Security (HTTPS), external authentication with
AD/LDAP, and reverse proxy-based authentication is now supported directly fromthe system administration pages of the web interface.
This functionality was released already with COMSOL Multiphysics 6.0 update 2.
USER MANAGEMENT AND ACCESS CONTROL ADMINISTRATION

Setting up user management and access control for a server database is now possible
from the database administration pages of the web interface.
This functionality was release already with COMSOL Multiphysics 6.0 update 2.

New Functionality in the Application Builder
Also see the Introduction to the Application Builder, Application Builder Reference
Manual, and Application Programming Guide for more information.
GENERAL IMPROVEMENTS

Apps With Resizable Subwindows
Apps built with the Application Builder no longer have to have just one big window.
You can now create applications with resizable subwindows just like the COMSOLCOMSOL MULTIPHYSICS|

13

Desktop itself. The Settings window for the Main Window node includes a new Main
window type list, where you can choose between the old Single window type or the newtype, Subwindows. The Main Window editor, which you open by double-clicking theMain Window node, now includes a new grid editor, similar to the Form editor. Eachcell in the editor is a subwindow where you can add one or more forms to appear as
windows when running the application. The sizes of the rows and columns can be
specified interactively by dragging them. They can also be entered manually in a new
section called Window Layout, which is added to the Settings window for Main Window
when Main window type is set to Subwindows. You can also control if dragging between
subwindows is enabled. There are also new form layouts for apps with subwindows; seebelow.

Running Apps on Linux ARM Computers
It is now possible to run compiled apps on Linux ARM computers.

Localizing Apps
Apps can now be localized using embedded language resource files. The Tubular
Reactor app in the COMSOL Multiphysics Application Library has been updated toinclude a demonstration of this feature. There is a new Languages library node that canbe added under Libraries for managing the localization, and there is a new Language
Localization section in the Settings window for Main Window for selecting the language
to use.

Replacing Libraries
Entries in the settings for the Files, Images, Sounds, and Languages library nodes can now
be replaced. Using the Replace File button in the table toolbar, you can select a new file
to replace an existing entry in the table. The replace action only changes the file data;
the name of the entry remains unchanged.

Showing Errors and Warnings
There is a new Show Errors button on the ribbon toolbar when using the Form editor
or Main Window editor. When enabled, any objects that are in an error or warning state(such as having a missing source) will show an icon in the corner of the object in theeditor. In the Application Builder tree, icons of window editor objects now show theirerror or warning status, and form icons show if they contain any object with suchstatus. This display happens regardless of whether you have enabled the Show Errors
setting or not.

14 |CHAPTER 1: RELEASE NOTESIMPROVEMENTS TO THE FORM EDITOR• Improvements to the New Form wizard:- The new Basic and Subwindows layouts are based on subwindows and appear
below Blank form. Basic replaces the Ribbon, sections, and graphics template, andSubwindows replaces the Ribbon, logo, sections, and graphics template, whichwere available in earlier versions. The template previously named Basic has beenrenamed to Single Form and now appears after the Subwindows template.
- The Inputs/Outputs tab in the Basic template in earlier versions has been split into
two tabs: Inputs and Outputs.
• A local form can now be converted to a global form or vice versa, either by pasting
or by drag-and-drop from a global to a local form location or vice versa.
• You can add a vertical scrollbar to forms by selecting the new Vertically scrollable
check box, which is available for:- Forms in a subwindow- Forms in a tabbed form collection- The dialog settings for a form
• The Image form objects now include a Stretch image setting that determines if theimage is scaled to fill the available space. When the form alignment is set to Fill, theimage will grow or shrink depending on available grid cell space.
• The Table form objects now include an Insert Row action. Also, you can now selectwhich of the properties in Table form objects that will be used to determine thenumber of rows in the table.
• In Graphics form objects, it is now possible to use all kinds of selections as the source.
This includes selections generated by a geometry or mesh sequence. Selections in
the geometry sequence are not accessible directly, only the ones generated by thegeometry features. Also, the previous Target for Data Picking section is now called
Data Picking. The previous Data picking check box has moved to this section and is
now called Enable data picking.
• The Internet Explorer-based .NET WebBrowser used to display in-line web andHTML pages for Video and Web Page form objects in Windows has been replacedwith the Chromium™-based CefSharp browser component. In the Settings windows
for those form objects, use the new Native browser on Windows list to choose
Chromium™ (CEF) (the default) or Internet Explorer®, which was the only option inearlier versions.

COMSOL MULTIPHYSICS|

15

• Applicable form objects now have an On focus gained event. The event occurs when
the user control associated with the form object becomes focused by the user.
• It is now possible to select individual components in a vector as the source of form
objects that support scalar data types. It is also possible to refer to a double array
property or double array declaration as the source for an input field.
IMPROVEMENTS TO THE METHOD EDITOR• You can now press F8 to launch the Run action, available on the context menus for
Method nodes.
• You can now choose Copy as Code to Clipboard from the context menu when rightclicking multiple selected Method nodes, if applicable. The copied code will be theconcatenation of the code of each of the nodes.
IMPROVEMENTS AND CHANGES FOR THE APPLICATION LANGUAGE

See also the Application Programming Guide for a complete overview of theapplication language for programming methods in the Application Builder for use inapplications, models, and add-ins.
• The saveApplicationAs and saveApplicationOnServerAs methods now havea boolean return value. If the return value is false, the user canceled the operationand the application was not saved.
• The application theme and image export theme properties found in the Themes
node settings are now available in the application language and support data access:// Set dark application theme
app.mainWindow().set("theme", "$dark");// Set light image export theme
app.mainWindow().set("imagetheme", "$light");

When running the app in the cross-platform user interface or in a web browser, theapp must be saved and uploaded for the application theme change to take effect.
The image export theme does not have this limitation.
• The AppModel.declaration() method is a new method for retrieving a list object
containing global DataSource objects. Additionally, the newForm.declaration() method retrieves a list object containing DataSource
objects defined under a given form. This list object is of type Declaration, and thistype exposes the same list methods as the FormObjectList, FormList, and
ItemList types. The DataSource.getType() method is a new method for
retrieving the same type of DataSource object and functions as the
FormObject.getType() method.

16 |CHAPTER 1: RELEASE NOTES• Two new overload methods for saveApplication andsaveApplicationOnServer are now available. They take a boolean argument that
determines if the user is prompted with a confirmation dialog box before saving.
The existing methods without an argument remain and function as before.
• The double conversion toString(double,int) andtoString(double,int,boolean) methods have been changed to use a format
based on significant digits rather than number of decimals. This change affects
existing apps. If you require the decimal behavior, you can use thetoString(double,String) method instead.

New Functionality in COMSOL Compiler™
For the COMSOL Compiler output, the platforms you can choose from now include
Linux, ARM. The macOS, ARM platform in previous versions has been changed to macOS,
Apple silicon, and the macOS platform in previous versions has been renamed as macOS,Intel.

New and Improved General Functionality in COMSOL Multiphysics
MULTIPHASE MATERIALS AND EFFECTIVE MATERIALSNew Multiphase Materials and Effective Materials nodes are available under Materials in
the model tree. Using the Settings window for these materials, you can define effective
material properties based on a set of mixing rules and the volume fractions and material
properties of each Phase or Compound. The Multiphase Material is intended to be usedin transport problems, and is especially useful for multiphase flow applications. You can
use the Effective Material node to model other types of mixed, averaged, and composite
materials.
NEW FIND AND REPLACE WINDOWThe Find and Replace window appears when you select the Find button in the Quick
Access Toolbar, or just by pressing Ctrl+F. You can search using a text string or aregular expression, and use various search options. You can then choose for which
occurrences you want to replace the text. You will also see a preview of the updated
text.
CREATE AND EDIT PARAMETERS

You can now right-click in text fields and tables cells that contain numbers andexpression in settings for many nodes in the Model Builder. It opens a Create Parameter

COMSOL MULTIPHYSICS|

17

dialog box where you can create a parameter to be inserted instead of the number or
expression. It is also added as a new parameter in a Parameters node of your choice.
Input fields and table cells in setting with the new Create Parameter option also
includes an Edit Parameter option in the context menu. The Edit Parameter option
shows up if the current text selection or cursor is inside an existing parameter name, or(available in the context menu of a table cell not in edit mode) if the cell contains only
such a name. It opens an Edit Parameter dialog box, similar to the Create Parameter
dialog box, where you can edit the expression, description, and name of the parameter.
Input fields and table cells containing expressions now also include tooltips that show
the evaluated value of the expression.
MEMORY USAGE INFORMATION FOR APPLICATION LIBRARIESWhen you hover over the Computation time value for a selected model in the Application
Libraries window, you can now see the maximum amount of physical memory (RAM)used while solving. You will also see information about the computer that was used
when logging the values for the memory usage and computation time.
NEW AND IMPROVED MATERIALS IN THE BUILT-IN MATERIAL LIBRARY

For the Built-in material library, the Structural Steel material has been extended withdata for plasticity, creep, viscoplasticity, and temperature-dependent properties. Also,a new generic Rubber material has been added.
PERFORMANCE IMPROVEMENTS

Several performance and scalability improvements for the assembly process and cluster
functionality have been made to improve the handling of large models.
IMPROVED SELECTION LIST WINDOWThe Selection List window has been improved in several ways:• For named selections under Boundary selections, for example, the context menu now
includes a Create Selection submenu with a number of selections types that you cancreate based on the chosen named selections.
• With an active selection (in a selected node in the model tree) it is now possible to
add to or remove the selection in the Selection List window to or from that active
selection using a context menu like Add to Geometric Entity Selection for Variables 1,
for example.

18 |CHAPTER 1: RELEASE NOTES• The Create Selection toolbar button in earlier versions has been renamed Create
Explicit Selection and now also works when you are in the Geometry branch of theModel Builder.
• There are now Collapse All and Expand All buttons in the Selection List toolbar.
• By default, the Selection List window now appears to the right in the COMSOLDesktop.
IMPROVEMENTS TO THE AUXILIARY DATA WINDOWThe Auxiliary Data window now supports showing output files generated from, forexample, data export features and reports. In connection with this improvement, theFilter Type toolbar button now includes new filter options: Input and Output. If Input
is selected, only input file items will appear in the window. If Output is selected, only
output file items will appear. Both button can also be selected or deselected at the sametime to show both input and output files or to show nothing at all.
The actions available to perform on input versus output file items in the Auxiliary Data
window are almost identical, with a few exceptions. The Import to Database action is
only available for input files, and a new action is available for output files: Save as
Version, which is available both in the context menu and in the toolbar. This action
saves an existing output database file as a new version in a database. Click a data itemin the Auxiliary Data window, and the Save as Version action should be available.
Clicking it will bring up a Save Fileset window, where you can edit certain aspects ofthe file, such as its title and tags, and see what underlying file resources are associatedwith the file.
With the support to also show output files in the Auxiliary Data window, a new Unsavedchanges status has been added. This status shows up for database files whose working

copy changes have not yet been saved to a database. The Unsaved changes status meansthat the output feature has written new data to a file in a temporary folder on the server
file system (the working copy of the database file), but that it is not yet saved to the
database. You will have to manually save the file to the database in this case, either via
the Save as Version option in the Auxiliary Data window or when saving the model via
the Save To option in the main File menu. The unsaved output files will show up in the
Auxiliary Data section in the fullscreen window.
In version 6.1, the Status window can include more than one status message for eachdata row.

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Some table settings have new names in version 6.1:
• The Property column has been renamed to Setting.
• The Source column has been renamed to Location.
The Set Source action has been renamed to Browse From, and the Show Source Location
has been renamed to Show Location.
NEW FULLSCREEN SELECT FILE, EXPORT, AND WRITE WINDOWS

A new Browse From option is now available for selected features that can generate
output files in COMSOL Multiphysics. The Browse From option opens a fullscreen
Select File window for selecting the output file, which can be either a new or existing
file. When you select Browse From to use the Select File window, you can select a filefrom other sources than the file system, such as selecting a file from a database.
New Export To and Write To options are now available for features that export data —such as geometry, mesh, and results data — and for writing reports and presentations.
They open fullscreen Export and Write windows, respectively, for selecting the locationand filename for the exported or written data. In these windows, you can export andwrite files to other locations other than the file system. You can, for example, store thefiles in a database.
OTHER IMPROVEMENTS IN THE COMSOL DESKTOP• In the Preferences dialog box, the categories on the left side are now displayed in atree instead of as a list. Many preferences pages have been reorganized into different,
often smaller, pages.
• The Model Builder and other trees that include Collapse All and Collapse Selectedactions in their toolbars now also include a Collapse Other action. This action
collapses all tree branches except the selected ones.
• When you have selected Click and Hide in the Graphics window toolbar, there is a new
Exit Click and Hide option in the Graphics window context menu.
• Certain tables now include an Insert Row action. The action can be found in thetable context menu and its toolbar. This action is supported by tables in the settings
for Parameters, Variables, Interpolation and Piecewise functions, and Polygon andInterpolation Curve geometry features.

20 |CHAPTER 1: RELEASE NOTESNew Geometry and Mesh Functionality
GEOMETRY FUNCTIONALITY• Update of selections after a geometry rebuild (geometry associativity) has been
improved.
• This release provides more robust 3D Boolean operations.
• The COMSOL Multiphysics part libraries have been upgraded to include additionaland more versatile pipe geometries and 2D and 3D geometries for common
repetitive microstructures, intended for homogenization using the representative
volume element (RVE) technique (also called representative element volume or theunit cell).
• In the settings for Revolve, it is now possible to specify a straight edge as therevolution axis.
• You now enter the Sketch mode directly when you create a 2D component,
geometry part, or work plane. With this, domains are not visualized and you candrag vertices and edges in the graphics. Click the Sketch button on the ribbon
toolbar to exit the Sketch mode.
• Visualization of a construction geometry is now also available outside of the Sketchmode as a dashed edge visualization.
• Measuring the objects of a geometry now also lists the number of finite voids in thegeometry.
• The operations Extrude, Revolve, and Sweep now also support virtual entities withcollapsed edges and merged vertices.
• It is now possible to select between displaying a warning or an error when thecondition of a Parameter Check is true.
• In the Sweep geometry feature, the direction of the sweep was wrong (reversed) inversion 6.0 and earlier versions when the edge was created by a Boolean operation
as an intersection of two faces using the COMSOL kernel. This bug has been fixed.
• The new tutorial Busbar Assembly Geometry — with Geometry Parts has been
added to demonstrate how to use geometry parts as a way to organize,
parameterize, and reuse geometries that you create in the software.
• The new tutorial Busbar Assembly Geometry — with Group Nodes has been added
to demonstrate how to use group nodes in the model tree as a way to organize thegeometry nodes that belong together.

COMSOL MULTIPHYSICS|

21• The new tutorial Light Bulb Geometry has been added to demonstrate how tocreate a geometry using Sketch mode to draw complex shapes.
• The new tutorial Steam Reformer Geometry has been added to demonstrate how
to use selections when creating a parametric geometry for analysis and how to set
up the selections needed for the physics definitions.
MESHING FUNCTIONALITY• The new menu item Cleanup and Repair contains the operations Fill Holes, Collapse
Entities, and Merge Entities. Use the new operation Merge Entities to merge points,
edges, or boundaries in a mesh. This can be used for closing a gap between two
disconnected components and for other types of repair and cleanup in a mesh.
• The new Collapse Entities can collapse edges or boundaries in a mesh. Use thisoperation to clean up a mesh of short edges or small faces.
• A new parameter, Maximum angle for trimming, enables you to control whether or
not a boundary layer mesh is trimmed in narrow corners. This parameter is available
regardless of the Handling of sharp edges setting.
• For the Boundary Layer Properties node, the new Adjust directions for each layer
option makes it possible to change the direction layer by layer. This setting is on bydefault.
• The Mapped operation is now supported for meshes that define their own geometricmodel.
• Use the new Vertex operation to generate vertex mesh. This is useful for isolated
points.
• The Swept operation is now supported for meshes that define their own geometricmodel. The operation has a new option, Remesh source faces, which enables
remeshing of the source faces, when possible.
• The input tables to the Create Vertices and Create Edges operations are now
automatically updated if the input mesh is changed. Selected chains of edges are
mapped to new chains of edges, if possible.
• You can now use named selections for mesh operations in a mesh that defines its
own geometric model. Named selections can be imported from a file, defined in ageometry sequence that you import into the mesh, or defined and used in thephysics defining a Filter or Partition dataset that you import into the mesh.
• When importing mesh files of the STL, 3MF, PLY, or VRML formats, the new
Create domains check box will make sure that domains (without mesh) are

22 |CHAPTER 1: RELEASE NOTESautomatically created within all finite void regions in the mesh. The same check box
is also available for the Fill Holes and Create Faces repair operations.
• The Import operation now supports the import of geometry into a mesh. The Free
Triangular and Visualization options specify how the faces of the geometry will bemeshed before being imported.
• For the Fill Holes operation, Fill holes tolerance has changed to Maximum holeperimeter and the old Maximum hole perimeter has changed to Perimeter.
• For exporting mesh to the NASTRAN and COMSOL Multiphysics formats, thesettings Export as linear elements and Export as second-order elements in earlier
versions of COMSOL Multiphysics have been changed to use only an Export as
second-order elements check box (clear it for linear elements).
• It is now possible to lock a mesh using the Model Builder context menu for mesh.
The Lock Mesh option converts the current meshing sequence to a single Mesh nodecontaining only its output mesh. The mesh is independent of any other data in themodel. Use the Disconnect from Geometry option to break any connection with thegeometry.
• The exact representation of circular edges are now used when creating geometry
from mesh.
• For meshes that define their own geometric model, the smooth evaluation of curved
and planar edges has been improved.
• The PLY file format import and export of quad elements have been improved.

New Functionality in the Physics Interfaces
PERIODIC CONDITIONS — DESTINATION SELECTION

The Settings window for all Periodic Condition and Periodic Flow Condition nodes has a
new option in the context menu, where you can add a Destination Selection section to
select the destination boundaries manually. This section is hidden when the automatic
detection is used, but you can activate it for a manual selection by right-clicking the
Periodic Condition or Periodic Flow Condition node and selecting Manual Destination
Selection. You can select it again to switch off the manual destination selection.
There is also a new Orientation of Destination section that becomes active when theTransform to intermediate map settings under the Orientation of Source section issomething other than Automatic.

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EQUATION FORM FOR PDE AND ODE INTERFACESThe PDE and ODE interfaces now have an Equation form setting similar to the one
found in physics interfaces as well as an accompanying equation display. This new
setting does not affect the form of the equation itself. It only controls theinterpretation of time derivatives of the dependent variables. Time derivatives are
expanded to multiplications by 2*pi*i*freq when the equation form is set toFrequency domain or when it is set to Study controlled and the study step is of frequencydomain type. See also Equation Form for PDE and ODE Interfaces in the backward
compatibility section below.
MOVING INTERFACE — PHASE FIELD THIN-FILM FLOWThe Phase Field Thin-Film Flow, Shell (pftffs) and Phase Field Thin-Film Flow, Edge
(pftffs) interfaces have been combined and renamed Phase Field Thin-Film Flow
(pftff).
MOVING MESH AND DEFORMED GEOMETRY

Boundary condition features controlling the boundary of a Deforming Domain node
under Moving Mesh or Deformed Geometry now include the possibility to exclude lowerdimensional selections from the condition. This can be useful for resolving conflicts
between adjacent boundary conditions at common edges or points, which canotherwise prevent finding a solution of the model or result in undesirable meshdeformation patterns.
A new Prescribed Mesh Velocity boundary condition is now available in the Moving
Mesh and Deformed Geometry interfaces. You can use it on boundaries of domains
with free displacement to specify the velocity of the boundary. The spatial frame in theadjacent domains moves in accordance with the velocity.
IMPROVED PDE INTERFACES• Dirichlet Boundary Condition and Constraint nodes are now available on edge andpoint levels in 2D and 3D PDE interfaces.
• In the More context submenu for the domain level, a Prescribed Solution node is now
available for prescribing the value of the solution on some domains in PDE
interfaces.
• Curl elements (shcurl and shcurl2) are now available in 1D PDE interfaces.
UPDATED PERIODIC CONDITIONSThe Periodic Condition settings now include a new Destination Selection section where
you can select the destination boundaries. This section is hidden when the automatic

24 |CHAPTER 1: RELEASE NOTESdetection is used, but the manual selection is activated using the Manual Destination
Selection context menu, which can be switched on or off.
There is also a new Orientation of Destination section that becomes active when theTransform to intermediate map settings under the Orientation of Source section issomething other than Automatic.
See also Periodic Conditions — Destination Selection in the Backward Compatibility
with Version 6.0 section below.

New and Updated Operators, Functions, and Definitions
LEAST-SQUARES FIT FUNCTION

You can now add Least-Square Fit function nodes under Global Definitions and under
Definitions on the component level. A Least-Square Fit node defines a least-squares fitof a function based on the input data, which can be a file, a local table, or a result table.
The function can be a general mathematical function with parameterized expressions.
GAUSSIAN PROCESS FUNCTION

The Gaussian Process function is intended for use with the Uncertainty Quantification
Module. If you have a license for the Uncertainty Quantification Module, you can now
add Gaussian Process function nodes under Global Definitions and under Definitions on
the component level. The Gaussian Process function defines a Gaussian process, which
is a surrogate model that gives an approximate prediction of the quantities of interest
in an uncertainty quantification analysis.
INTERPOLATION FUNCTION IMPROVEMENTS• In Interpolation function nodes, you can now choose Function from the Data source
list to use another user-defined function as the data source. This functionality canbe useful for creating primitive and inverse functions or for downsampling.
• For Interpolation functions defined on a component level, when requesting to define
variables using spatial coordinates for a mesh frame, you can now select a new
Reinterpolate interpolation data on computational mesh check box. Doing so makes
it possible to evaluate variables using Lagrange interpolation with cached values
evaluated at Lagrange points on the computational mesh when using aninterpolation function to define spatially dependent variables.

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NEW BUILT-IN OPERATORS AND FUNCTIONS• The new built-in mathematical functions gcd and lcm are now available for thegreatest common divisor and least common multiple, respectively.
• A new built-in withparam operator is now available for accessing the solution
parameters for the solution defined by a given solver tag.

New Functionality in Studies and Solvers
STUDIES AND STUDY STEP FUNCTIONALITY• Improvements to the Time-Dependent Solver:- The RK34, Cash-Karp 5, Dormand–Prince 5, Adam-Bashforth 3, and Classical
Runge–Kutta methods now support coupled systems of mixed-order time
derivatives.
- The time-dependent solver now also supports explicit time-stepping methods.
- Note that the Time-Explicit Solver is no longer available in the Model Builder(unless you open a model that was created in an earlier version of COMSOLMultiphysics and that uses it).
• Improvements to the reduced-order model features and study steps:- An Equation form setting has been added to the stateful reduced-order modelfeatures and study steps.
- Model control inputs in constraints are now also available for stateless reducedorder models.
• Improvements to the adaptive mesh refinement and error estimation:- The design for both stationary and time-dependent adaptation has been
improved so that more specialized settings have been moved to the Adaptive Mesh
Refinement and, when applicable, Error Estimation subnodes under the stationary,eigenvalue, and time-dependent solver nodes.
- A new Advanced section is available in the settings for the Adaptive Mesh
Refinement node. It includes a Use classic method for vector elements check box.
If this is selected, the old 6.0 adaptive method will be used in which higher-order
DOF names for vector elements are ignored in the residual calculation.
Otherwise, a new adaptive method with a more rigorous calculation is used. The
classical method exhibits faster mesh convergence for lumped parameters and is

26 |CHAPTER 1: RELEASE NOTEStherefore the default setting for the predefined adaptive mesh study in the RF
Module and can be used for models using linear curl elements.
- A new option to not store error estimates for L2 and Functional adaptation isavailable in the Adaption and Error Estimates section in the settings for theStationary study step.
• The Values of linearization point settings now support both physics controlled anduser-controlled linearization points. It is also now available for the following study
types: Eigenvalue, Eigenfrequency, Mode Analysis, Boundary Mode Analysis, Frequency
Domain Perturbation, and Linear Buckling.
• There is now support for computing and storing left eigenvectors using the
Eigenvalue solver.
• For the GCRO-DR methods in the iterative solver, there is a new Minimum numberof restarts field, which is available when Reuse subspace is set to Automatic. In thisfield, you can specify a minimum value for the number of restarts. This can be useful
to control in situations where a subspace exists between solver calls and needs to becleared between solver calls — for instance, in a frequency sweep.
CLUSTER AND BATCH FUNCTIONALITY• New COMSOL cluster options on Linux:
The -mpiofiprovider option is now available for choosing an OFI (Open Fabrics
Interface). This option is not supported for ARM processors.
A new option for the command-line option -scalapack: scalapack. It uses
Netlib’s ScaLAPACK.
• For COMSOL Hydra commands, fiinfo and fipingpong are now available forrunning fi_info and fi_pingpong commands, respectively.

New and Improved Results and Visualization Functionality
GENERAL NEW RESULTS AND VISUALIZATION FUNCTIONALITY• The new Add Predefined Plot window contains, if applicable, plots that arepredefined by the physics interfaces in the model but are not created directly when
computing the solution. You can add such plots to plot groups under Results fromthe Add Predefined Plot window.
• In version 6.1, only the relevant postprocessing features, dependent on the physics
in the current COMSOL Multiphysics simulation model, are visible. To show allfeatures under Results, select the All Dataset Types, All Plot Types, All Numerical

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Evaluation Types, and All Export Types check boxes in the Show More Options dialog

box.
• Direct shadows are now supported when you run the COMSOL Desktop with
OpenGL rendering, optimized for quality. You can enable direct shadows using
shadow mapping in the Scene Light menu in the Graphics window’s toolbar or in the
Visual Effects section in 3D View nodes Settings window, where you can also control,
among other properties, the shadow strength and softness. All lights in the 3D
Graphics view cast shadows by default. You can turn it off by clearing the Cast
shadows check box.
• Improved rendering performance, both in general and in particular for effects suchas transparency and ambient occlusion.
• Anisotropic specular highlighting is now available in the Material nodes’ Settings
windows under Appearance. You add it by adding a value in the Anisotropy field (orusing the associated slider). You can use it to give an effect that could be the resultof machining or polishing in a certain direction, which is determined by the
Anisotropy axis setting.
• You can now browse, search, and manage color tables using the new Color Table
window, which you open by clicking the Change Color Table button next to the Colortable setting in plot nodes. Using the Color Table window, you can search for color
tables and get previews of the available color tables, which are grouped into
categories, before switching to another color table. It is now also possible to store
and load custom color tables in the model using the option to add Color Table nodes
under Results>Color Tables. Such color tables appear under In Model in the Color
Table window.
• The Internet Explorer-based .NET WebBrowser used to display in-line web andHTML pages in the .NET UI has been replaced with the Chromium™-based
CefSharp browser component. This upgrade should be seamless and not affect you
as a user. See Backward Compatibility with Version 6.0 for some compatibility
information.
• For inserting Greek and other characters, a number of Greek symbols from the
textgreek LaTeX package have been added for display as text in plots: \textalpha,\textbeta, and so on; \textAlpha, \textBeta, and so on; and some additional
symbols.
NEW AND IMPROVED DATASET AND EVALUATION FUNCTIONALITY• There is now support for adding selections to Cut Line datasets.

28 |CHAPTER 1: RELEASE NOTES• For Shell datasets, there is now a Displacement of normals array input, where you canenter an additive correction to the shell’s orientation that should be applied whenevaluating in the spatial frame.
• The trees with predefined expressions that you open by clicking the Insert Expression
or Replace Expression button now contain variables defined by the datasets.
• Using the new Array Factor dataset, you can define array factors for use in radiation
pattern plots in RF simulations of antenna arrays, simplifying the analysis for aperiodic antenna array. You can choose an Array Factor dataset as the dataset for the
input data in Radiation Pattern plots.
• In the Spatial FFT dataset, you can now change the sign convention to suit the ones
used for electromagnetic waves, for example.
• It is now possible to export WAV audio files with 32-bit floating point data.
• There is now an option for disabling interpolation between stored time steps in theTime Integral and Time Average datasets.
• You can now apply an out-of-plane wave number in Extrusion 2D datasets.
NEW AND IMPROVED GRAPHICS AND PLOT FUNCTIONALITY• For 2D Surface plots, it is now possible to create discrete (banded) plots by choosing
Discrete instead of Continuous from the new Color table type list. You can then also
specify the number of bands.
• A new Pellets plot type is available for visualizing a flow of pellets or similar objects
as spheres or as three orthogonal filled circles (slices).
• A new Coordinate System Point plot is available for showing the orientation of asource in postprocessing, such as plotting the coordinate system in a source point.
• You can now use the Plot Previous, Plot Next, Plot First, and Plot Last buttons for any
level of a parameter or time in a multiparametric sweep. You can choose the level toswitch to from a menu to the right of those buttons.
• The algorithm for finding and drawing the best streamlines has been improved forflat streamline plots in the 2D and 3D plot groups; that is, the rendering ofstreamlines has been improved for 2D Streamline and 3D Streamline Surface andStreamline Multislice plots.
• It is now possible to inherit the transparency and Fresnel transmittance between
Transparency plot subnodes in a plot group.
• You can now place legends for 1D graph plots outside the graph. In the settings for
1D Plot Group nodes, you can choose Outside graph axis area from the Layout list tochoose a position outside the graph.

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• A Show units option in now available in graph plot groups with Color Expression
subnodes to show a unit above the color legend.
• For Graph Marker subnodes, you can now choose Line intersection from the Display
mode list to display the intersections with vertical, horizontal, identity, or general
straight lines, including the display of those lines.
• You can now add Graph Marker subnodes to Line Graph, Octave Band, and Table Graphplots.
• Color table files with RGB data can now use tabs, commas, or semicolons as
separator characters, in addition to spaces.
• It is now possible to specify the point size in plots and plot subnodes that plot
markers: Annotation plots; Max/Min Line, Max/Min Surface, Max/Min Volume plots; Table
Annotation plots; Graph Marker plot subnodes; and Marker plot subnodes in 2D and3D plot groups.
• There is now a setting for controlling the plot position and whether to show
maximum and minimum values and units for color legends in graph plot groups.
• You can now specify a default for the line width in graph plots on the Graph Plotspage in the Preferences dialog box. Doing so can be useful as a personal preferenceor for presentations using a projector; being able to increase the line width will
improve the visibility, for example. The default line width is Default from preferences
for a plot created from the COMSOL user interface and 1 for a plot created fromthe API. The default value of the preference is 1.
• In the Selection subnode for plot nodes, you can now make selections at geometric
entity levels that are lower than the plot group’s dimension (for example, selecting
boundaries for a 3D plot). The selection is mapped from the chosen geometric
entity level to the plot group’s geometric entity level using adjacency mapping.
• It is now possible to disable inclusion of parameter tuples for solutions in automaticlegends in the following graph plots: Global, Point Graph, and Octave Band. The new
Solution check box in the Legends section is selected by default; clear it to make thelegend text shorter.
• The Coordinate System plots can also be used for plotting an arbitrary matrix
variable. For that purpose, it is now possible to choose Columns or Rows from the
Vectors to plot list, when the coordinate system’s plot source is a matrix variable. For
example, plotting the deformation gradient’s columns as a triplet of arrows gives agood picture of the local deformation and rotation of the material.

30 |CHAPTER 1: RELEASE NOTES• The default marker position has been changed from Interpolated to In data points.
The new default position, In data points, presents the data in a form that is closer tothe underlying numerical solution than Interpolation.
• For Animation export features where the target is a file, a new HD option for theimage size is available and provides animations with 1280-by-720 pixels.
• The line width in graph plots can now be specified as a preference on the
Results>Plot>Graph Plots page in the Preferences dialog box.
• Surface Slit plots can now take any dataset as their input.
• There is now a Rounded end caps check box (selected by default), which you can clear
to remove the rounded tube end caps in 2D and 3D Line plots using tubes and 2D
and 3D Tube Data plots.
• To improve graph plot coloring, a Long graph cycle that contains 19 colors is now
available. The graph cycle used in 6.0 and earlier versions is now called Default.
• The Particle Trajectories and Ray Trajectories plots now accept the following datasets
as inputs:- Particle and Ray- Particle Bin and Ray Bin- Intersection Point 2D and Intersection Point 3D- Receiver 2D and Receiver 3D- Transformation 3D and Receiver 3D• A Color table transformation list has been added to the settings for Whirl plots.
• The norm for the arrows (the arrow length) is now available as a built-in expression,
Arrow length, for the Color data in Color Expression subnodes added to Arrow plots
and to Particle Trajectories, Point Trajectories, and Ray Trajectories plots where thePoint style is set to Arrow.
NEW AND IMPROVED REPORT AND PRESENTATION FUNCTIONALITY• There is now support in the report generator for linked images in reports on theMicrosoft Word® format.
• It is now possible to use custom labels on the title page of reports.
• The presentation of matrix-valued properties has been improved.
• Only material properties that are used in the model are included in the report.

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• Reports on Method Call features now include the method code, if desired.
• The allocation of vertical space on presentation slides with mixed nonimage
contents, for example text and equations, has been improved.

New Java® API Methods
The following new methods are now available:
MEASURING GEOMETRIC ENTITIES AND GEOMETRIC OBJECTS

Measuring geometric entities in comp(), geom(), and mesh() can now be done using
the same methods:
model.component(<tag>).measure().MeasurementMethod;model.component(<ctag>).geom(<tag>).measure().MeasurementMethod;model.component(<ctag>).mesh(<tag>).measure().MeasurementMethod;
PREVIEW PLOTS OF DATASETS

There is now API support for creating preview plots of datasets, using the createPlot
method:DatasetFeature.createPlot();
CONTROLLING THE PLOT PREVIOUS, PLOT NEXT, AND SIMILAR
BUTTONS

There are now the following new Boolean API methods for stepping and checking if
such operations are applicable: stepPrevious, stepNext, stepFirst, stepLast;
canStepPrevious, canStepNext, canStepFirst, and canStepLast. All methods
support an integer input argument level for the level to step in a time-dependent
parametric sweep, for example. You can also get the number of levels using
getStepLevels().

New COMSOL Server Functionality
The Security preference for file system access now also applies to clients connected to
COMSOL Server using the COMSOL API.

General Backward Compatibility Considerations
COMSOL Multiphysics version 6.1 can open MPH-files saved from COMSOLMultiphysics versions 4.0–6.0.

32 |CHAPTER 1: RELEASE NOTESCOMSOL Multiphysics version 6.1 can run Java® files saved from COMSOLMultiphysics versions 4.0–6.0. However, the Java® files may need to be modified inaccordance with information in this document and may need to be recompiled withthe comsol compile command in version 6.1.

Backward Compatibility with Version 6.0
NEW CEFSHARP BROWSERThe Chromium™-based CefSharp browser component replaces the Internet Explorerbased .NET WebBrowser component in version 6.1.
In the Video and Web Page form objects, there is now a Native browser on Windows
option in the settings to determine if the Internet Explorer®-based .NET WebBrowser
component from earlier versions should be used instead. The default value for thenative browser is Chromium™ (CEF) but all existing models have the setting set toInternet Explorer® by default to maintain the functionality from earlier versions. Use
the launcher flag cs.legacywebbrowser=true as a way to keep the previous browser
component instead of CefSharp.
The CefSharp browser component stores user data such as cookies, browser history,
and local storage in a folder. This cscefcache folder is placed among the temporary
files of the client and persist between COMSOL and browser sessions. You can delete
the cscefcache folder to clear this data. The CEF log output is written toUsers\[user]\.comsol\6.1\logs\cef.log. The log level can be controlled using
the cs.cefloglevel launcher argument, which accepts the values info, warning,error, and fatal.
EQUATION FORM FOR PDE AND ODE INTERFACES

When adding a PDE or ODE interface in the user interface, the equation form will by
default be set to Study controlled. This will lead to a different interpretation of time
derivatives in frequency-domain studies compared to previous versions. When creatinga new PDE or ODE interface from the API or opening a model saved in a previous
version, the equation form will be set to Time domain, which corresponds to the
behavior in previous versions.
THE FLASH MOVIE FORMAT

For movie export, the Flash format is no longer available as of version 6.1.

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TIME-EXPLICIT SOLVER

The Time-Dependent Solver node settings now includes the time-explicit methods fromthe Time-Explicit Solver node that was available in the Model Builder in earlier versions.
The Time-Explicit Solver node is still available in models created in earlier version of
COMSOL Multiphysics. It is also available in the COMSOL API.
MODEL REDUCTION STUDY STEPThe Study step for eigenmodes and Study step for constraint modes settings in version
6.1 correspond to Defined by study step in previous versions because it is not possible
to use one study step for two different solution types.
PERIODIC CONDITIONS — DESTINATION SELECTION

The Destination Selection subnode under Periodic Condition nodes has been removed inversion 6.1 and has been replaced by an optional Destination Selection section in the
Settings windows for Periodic Condition nodes. It can still be added from the API for
backward compatibility. The Destination Selection subnode was used for two purposes:• To provide a manual destination selection in cases where the automatic detection
failed for some reason (for example, in models with curved boundaries). The
selection of the feature was used as destination domains. When the All boundaries
option was selected for the selection list, the automatic destination was used fromthe parent periodic condition.
• To add a manual orientation for vector transforms of the destination boundaries.
The Orientation of Destination section was used for this.
For more information about the API compatibility, see COMSOL 6.1 API Changes.
FLASH MOVIE FORMATThe Flash movie format is no longer available for export of movie files using theAnimation feature. Animation features in models created using version 6.0 or earlier
where the format is set to Flash now use GIF as the format in version 6.1.
STREAMLINE PLOT CHANGESFor 2D Streamline and 3D Streamline Surface and Streamline Multislice plots, thealgorithm for finding and plotting streamlines has been improved. The Density setting
in version 6.0 and earlier versions has been replaced with the Maximum distance setting,which is the inverse of the Density. A corresponding Minimum distance setting has also
been added. When opening models from version 6.0 and earlier versions, the Minimum
distance is assigned a value that is 0.05 times the Maximum distance. This is a reasonableheuristic, but it is not guaranteed to give a good result in all cases.

34 |CHAPTER 1: RELEASE NOTESPHYSICS SYMBOLS IN 1D AND 0D GEOMETRIESThe Physics Symbols section in the settings for physics interfaces, features, andboundary conditions has been removed for all components with dimension less than
2D. This change might cause issues with old public API code that accesses any physics
symbol properties in 1D or 0D, even though they did not have any effect in earlier
versions either.

Backward Compatibility with Version 5.6
PAIR FEATURESThe new framework for pair features can affect old models, although the goal is thatthe effect is as small as possible. When opening an old model in the Model Builder, pairfeatures are migrated using the following main steps:
1 Add a default pair feature with the Disconnect pair check box selected to ensure thatthe default pair feature does not contribute any new constraints or equations to themodel.
2 Move all fallback features that were located under the pair features in 5.6 to the level

below the physics interface. The selection of these moved features will typically get
the same active selection as the pair feature they belonged to in 5.6. Because those
moved features now have an overlapping selection with that pair feature, they will
act as an equivalent fallback feature to the pair feature.
3 Optimize all moved fallback features by merging exact duplicates into one feature,including existing features such as the default features. In many situations, the result
will be that only the default feature of the physics will remain because most fallback
features under pair features in 5.6 were identical to the default feature of the physics
interface.

Potential Issues
If the optimization in Step 3 above cannot merge all features, some moved fallback
features will remain and be placed before their pair feature. Normally, a pair feature in
5.6 overrode all features before it, so if the moved fallback also overrides these features,the selections should not change for them. However, there can be configurations
where the selection may change because of special schemes for overriding andcontributing between features. One example is shell interfaces that have pair featureson the same level as the physics interface. The pair feature can then contribute with afeature that the moved feature will override. Such cases are difficult to detect during
migration and can create a discrepancy in some selections between the versions.

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PHYSICS AND VARIABLES SELECTIONSThe Discretization column is removed from the table to the more advanced tree option,
which is shown when the Modify model configuration for study step check box isselected.
USER DOCUMENTATION NODES IN THE PHYSICS BUILDERThe User Documentation nodes in the Physics Builder are no longer available in version
6.0.

Backward Compatibility with Version 5.5
The selections imported from Filter datasets in version 5.5 are now given tags by acorrected scheme that makes them independent of the language setting in COMSOL.
If you have written API code using such selections, the code might need to be updated
to handle the new naming principle.
In version 5.6, the getAdjSparse method has been deprecated and may be removed
in a future version.
In the Octave Plot, the Solid setting for Type is now called Bar, and the Curve setting
is now called Outline. The corresponding API property values are now bar andoutline.
The default value for the compact aggregation setting for the smooth aggregation
AMG multigrid solver, from version 5.6, is set to off.

36 |CHAPTER 1: RELEASE NOTESAC / DC M o dule
New Functionality in Version 6.1
MAGNET FEATURE FOR ELECTROMAGNETIC MACHINE MODELINGThe Magnet feature can be used to model a magnetized domain or a regular pattern ofmagnetized domains. The direction of the magnetization can be specified by means ofan expression, or by simply selecting the north and south pole boundaries. The feature
comes with pattern recognition logic, making it easier to set up Halbach arrays andcomplicated rotor patterns. For formulations that support electrical currents, thisfeature makes it possible to impose electrical insulation on interior boundaries, making
it easier to compute circulating currents and losses in segmented magnets.
The Magnet feature comes in two variants: a Nonconducting Magnet feature for the
Rotating Machinery, Magnetic interface and for the Magnetic Fields, No Currents
interface (for the latter, simply called Magnet), and a Conducting Magnet feature for the
Rotating Machinery, Magnetic interface and for the Magnetic Fields interface (for the
Magnetic Fields interface, simply called Magnet). In addition to support for interior
electric insulation, the Conducting Magnet feature supports the Loss Calculation
subfeature. Both variants support the Remanent flux density and Nonlinear permanent
magnet constitutive relations.
MULTIPHASE WINDING FEATURE FOR ELECTROMAGNETIC MACHINEMODELING

The Multiphase Winding feature is used to model a regular pattern of coils, as typicallyused in electric motor modeling in 2D. Within this pattern, a coil or group of coils
carrying the same current at the same phase angle is commonly referred to as a phase.
The Multiphase Winding feature simplifies the excitation of a system of multiple phasesby enforcing standard winding layouts. The feature uses automated patternrecognition logic to detect inconsistent configurations. For cases that do not follow astandard pattern, the feature supports a User Defined layout configuration.
The Multiphase Winding feature supports the Loss Calculation subfeature for automateddetermination of the resistive losses. It is available for the Rotating Machinery,
Magnetic physics interface in 2D.

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PASSIVE CONDUCTOR FEATURE FOR THE MAGNETIC FIELDS INTERFACE

The Passive Conductor feature in the Magnetic Fields interface makes it possible toimpose electrical insulation on interior boundaries, making it easier to compute
circulating currents and losses in segmented conductors. The feature shows many
similarities with the Conducting Magnet, with the difference that this feature only
supports B-H constitutive relations that do not include the magnetization: Relative
permeability, B-H curve, and Effective B-H curve. Like the magnet, the Passive Conductor
feature supports the Loss Calculation subfeature for determining the resistive losses.
PASSIVE CONDUCTOR FEATURE FOR THE MAGNETIC FIELDS, CURRENTS
ONLY INTERFACE

The Passive Conductor feature in the Magnetic Fields, Currents Only interface is a
simplified version of the Conductor feature from the same interface. It does not require
the specification of terminal and ground boundaries and is not swept over byautomated source sweep studies; it is used to model a conductor without feeding. The
feature supports an Electric Insulation subfeature, which imposes electrical insulation oninterior boundaries. This functionality makes it easier to compute circulating currents
and losses in segmented conductors.
MAGNETOHYDRODYNAMICS MULTIPHYSICS INTERFACES

The new Magnetohydrodynamics Multiphysics interface consists of the Magnetic
Fields interface (or the Magnetic and Electric Fields interface), the Laminar Flowinterface, and a Magnetohydrodynamics multiphysics coupling. The coupling applies theLorentz force from the electromagnetics interface to Laminar Flow, and — in return— applies the Lorentz velocity term from Laminar Flow to the electromagnetics
interface.
The multiphysics interface comes in three variants: 2D with out-of-plane electric
currents, 2D with in-plane electric currents, and 3D. The 2D variant with out-of-planecurrents uses the Magnetic Fields interface, the other two use the Magnetic andElectric Fields interface. All three variants are available with the AC/DC Module only.
The multiphysics coupling feature can be used separately as well, and is available with
the AC/DC Module and the Plasma Module.
LIQUID METAL MATERIAL LIBRARY FOR MAGNETOHYDRODYNAMICS

The AC/DC material library has been extended with a Liquid Metals folder formagnetohydrodynamics (MHD) modeling. This new folder contains materials withmaterial properties for the thermal conductivity, electrical conductivity, dynamic

38 |CHAPTER 1: RELEASE NOTES

viscosity, and density of various liquid metals, including titanium, steel, iron, nickel,
copper, aluminum, magnesium, tin, lithium, sodium, and others.
TIME-DOMAIN SUPPORT FOR THE MAGNETIC AND ELECTRIC FIELDSINTERFACE

The Magnetic and Electric Fields interface now has support for the Time Dependent
study type. Furthermore, the default exterior boundary condition has been updated
from Magnetic Insulation with Electric Insulation, to Magnetic Insulation with Ground,making it consistent with the default Magnetic Insulation boundary condition in the
Magnetic Fields interface.
COVARIANT FORMULATION IN 2D AXISYMMETRY

The Magnetic Fields interface and the Magnetic and Electric Fields interface now use
the covariant formulation in 2D axisymmetry. The covariant formulation maps thesolution on the shape functions differently and is much better able to handle theinherently singular properties of the axis in cylindrical coordinate systems. The
covariant formulation gives better performance, better numerical stability, and better
accuracy.
MAGNETIC FIELDS FORMULATION MAGNETIC FIELDS NO CURRENTS
COUPLING

The Magnetic Fields Formulation Magnetic Fields No Currents Coupling assures continuityof the normal magnetic flux density and the tangential magnetic field acrossboundaries between the Magnetic Fields, No Currents interface and the Magnetic
Field Formulation interface. This new multiphysics coupling is especially suitablewithin the context of superconductor modeling.
LAYERED IMPEDANCE BOUNDARY CONDITION FOR THE MAGNETIC
FIELDS INTERFACEThe Layered Impedance Boundary Condition is an extension of the Impedance Boundary
Condition, which makes it possible to model a sequence of geometrically thin layers on
top of a substrate. It is used on exterior boundaries where the field is known topenetrate only a short distance outside the boundary. In brief, this feature combines a
Layered Transition Boundary Condition with an Impedance Boundary Condition. This newfeature is available for the Magnetic Fields interface.

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Updated Functionality in Version 6.1
CIRCUIT EXTRACTION IMPROVEMENTS

The Circuit Extractor add-in converts matrices of lumped quantities into electricalcircuits. These circuits can then be used as a lumped representation of anelectromagnetic device. Typically, a finite element model is subjected to a Source Sweep
study and the lumped matrices are extracted. These matrices are then fed into the
Circuit Extractor. The resulting circuit is validated by comparing it with the original
finite element model. Once validated, the circuit can be used as a lumped
representation for cases where the finite element model would be computationallydemanding. The method can be seen as a physics-based alternative to reduced-ordermodeling (ROM) or vector fitting.
The Electrostatics; Electrostatics, Boundary Elements; and Electric Currents interfaces
now produce capacitance (and resistance) matrices in a format that is directlycompatible with the Circuit Extractor add-in. The Magnetic and Electric Fields
interface now supports the Stationary Source Sweep and the Frequency Domain Source
Sweep study types and generates impedance, resistance, and inductance matrices in aformat that is compatible with the Circuit Extractor add-in. The Circuit Extractor itself
has now been extended to support impedance matrices.
MAGNETOSTRICTION IMPROVEMENTS

The old Magnetostriction multiphysics coupling has been split into a Nonlinear
Magnetostriction coupling and a Piezomagnetic Effect coupling (the latter is also known
as linear magnetostriction).
Together with the new multiphysics couplings, two new Ampère’s Law variants(Ampère’s Law, Nonlinear Magnetostrictive and Ampère’s Law, Piezomagnetic) and two
new multiphysics interfaces (Nonlinear Magnetostriction and Piezomagnetism) havebeen introduced. The new multiphysics interfaces are based on the Magnetic Fields
interface together with the Solid Mechanics interface. The new Ampère’s Law, Nonlinear
Magnetostrictive feature supports the Loss Calculation subfeature. This subfeature allows
for automated determination of resistive and magnetic losses in laminated iron, using
empirical loss models, such as Steinmetz or Bertotti.
A new constitutive relation, Analytic magnetization curve, is available in the ordinaryAmpère’s Law feature (given that the Material type of this feature has been set to Solid).

The new multiphysics couplings, new Ampère’s Law features, and new constitutive
relation are available with the Magnetic Fields and the Rotating Machinery, Magnetic
interfaces. The couplings and the dedicated features require the AC/DC Module,

40 |CHAPTER 1: RELEASE NOTES

together with either the Structural Mechanics Module, Acoustics Module, or MEMS
Module. The new constitutive relation only requires the AC/DC Module.
COIL IMPROVEMENTS

For the Coil feature, the Homogenized multiturn conductor model has been updated.
The coil wire cross-sectional area can now be derived from the slot Filling factor. The
thickness of the wires is then derived from the area of the selected domains and thedesired relative amount of copper in the coil cross section. This setting is frequently
used in motor modeling.

New and Updated Models in Version 6.1
GENERAL APPLICATION LIBRARY RESTRUCTURING

The AC/DC Application Library has been restructured to provide a better overview
of models per application area, per level of difficulty, or per used physics.
ELECTRIC FIELD FROM POWER LINESPower lines are commonly used as a means of transmitting electrical power across large
distances. In this tutorial, towers transmitting high-voltage three-phase AC power aremodeled, and the resulting electric field is computed. The towers have two shielding
lines above the phase lines, which protect the tower from lightning strikes.
This new model also illustrates the strength of using the boundary element method(BEM) for modeling, which is used by the Electrostatics, Boundary Elementsinterface.
MAGNETIC FIELD FROM POWER LINESPower lines are commonly used as a means of transmitting electrical power across large
distances. In this tutorial, towers transmitting high voltage three-phase AC power aremodeled, and the resulting magnetic field is computed. The towers have two shielding
lines above the phase lines, which protect the tower from lightning strikes.
This new model uses the Magnetic Fields interface to compute the magnetic field.
ELECTRIC FIELD BETWEEN CONCENTRIC CYLINDERSThis new introductory model treats the electrostatics problem of two concentric
cylinders of infinite length, which is commonly found in textbooks. Since the problem
can be solved analytically, the model can be used to compare theory with numericalsimulation results. Two cases are considered: one with a fixed potential on each

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cylinder and the other with a surface charge density on one cylinder and a fixed
potential on the other.
MAGNETIC FIELD FROM AN INFINITE CONDUCTORThis new introductory model creates a simple model of the magnetostatics problem
with a wire of infinite length carrying current, which is commonly found in textbooks.
Since there is an analytical solution to this problem, the model can be used to compare
theory with numerical results from the simulation. The wire still has a finite radius inthis example, giving different solutions for the regions inside and outside of the wire.
HARTMANN BOUNDARY LAYERThis new introductory magnetohydrodynamics model illustrates the effect of an
external magnetic field on the laminar flow profile of a conducting fluid. The fluid
velocity transverse to the magnetic field induces volumetric currents via theelectromotive force, creating a Lorentz force on the fluid in the direction opposite theflow direction. The fluid velocity profile between two no-slip walls are compared withanalytical values for different values of the Hartmann number.
MAGNETOHYDRODYNAMICS PUMPThis new introductory model illustrates the action of a magnetohydrodynamics pump.
A moving magnetic field is created by three-phase coils, and the contrary induced
magnetic field due to eddy currents in the liquid creates a repelling force on the liquidin the column, generating motion. This type of induction pump is used in, forexample, high-temperature cooling systems, where the lack of moving parts and the
pumped liquid being kept in a hermetically sealed system are clear advantages.
MAGNETIC BRAKE

This model has been updated to use the new time-domain support for the Magnetic
and Electric Fields interface.
PERMANENT MAGNET MOTOR IN 2D

This model has been updated to use the new Magnet feature (with the Loss Calculation
subfeature), and the new Multiphase Winding feature. It also uses the new Filling Factor
option for specifying wire thickness.

42 |CHAPTER 1: RELEASE NOTESADDITIONAL UPDATED MODELS

The following models have been updated to use the new Evaluation Groups, used forlumped matrix extraction (see Circuit Extraction Improvements above for moredetails):• Modeling a Capacitive Position Sensor Using FEM/BEM• Tunable MEMS Capacitor
The following models have been updated to use the new Magnet feature (and in mostcases the corresponding Loss Calculation subfeature):• Generator in 2D• Linear Motor in 2D• One-Sided Magnet and Plate• Permanent Magnet• Permanent Magnet Motor in 3D• Quadrupole Lens
• Rotating Machinery 3D Tutorial,• Modeling of an Electric Generator in 3D• Static Field Modeling of a Halbach Rotor

Backward Compatibility with Version 6.0 and Earlier
The old Magnetostriction multiphysics coupling has been split into a Nonlinear
Magnetostriction coupling and a Piezomagnetic Effect coupling (the latter is also known

as linear magnetostriction). Old Magnetostriction multiphysics couplings and old
Ampère’s Law, Magnetostrictive features in existing models will continue to work but
will show an obsolete functionality warning.

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Acoustics Module
New Functionality in Version 6.1
NEW ACOUSTIC STREAMING MULTIPHYSICS

The two new Acoustic Streaming from Pressure Acoustics and Acoustic Streamingfrom Thermoviscous Acoustics multiphysics interfaces are used to model the physicalphenomenon acoustic streaming, which is when an acoustic field induces a fluid flow.
The multiphysics couplings Acoustic Streaming Domain Coupling and Acoustic Streaming
Boundary Coupling are used to compute the forces, stresses, and boundary slip velocities
that the acoustic field induces in the fluid, generating flow. The interfaces couple afrequency-domain acoustic field to a stationary or time-dependent fluid flow. Acoustic
streaming is important in microfluidics and lab-on-a-chip systems for applications suchas particle handling, mixing of fluids, and microfluidic pumps.
PHYSICS-CONTROLLED MESH FOR ACOUSTICS PHYSICS

The generation of a physics-controlled mesh has been extended to more acoustics
interfaces. A physics-controlled mesh results in the generation of a good initial meshthat fulfills best meshing practices, resolves the wave phenomena, and createsboundary layers. Physics-controlled mesh has been added for:• Pressure Acoustics, Boundary Element• Pressure Acoustics, Kirchhoff-Helmholtz• Pressure Acoustics, Asymptotic Scattering• Pressure Acoustics, Time Explicit• Nonlinear Pressure Acoustics, Time Explicit• Elastic Waves, Time Explicit• Thermoviscous Acoustics, Frequency Domain• Thermoviscous Acoustics, Transient
THERMOVISCOUS-THERMOELASTICITY BOUNDARY MULTIPHYSICSCOUPLING

Two new multiphysics interfaces, the Thermoviscous Acoustic-Thermoelasticity
Interaction, Frequency Domain and the Thermoviscous Acoustic-Thermoelasticity
Interaction, Transient interface, combine the Thermoviscous Acoustics, Frequency
Domain or Transient interface with the Thermoelasticity multiphysics interface using

44 |CHAPTER 1: RELEASE NOTESthe new Thermoviscous Acoustic–Thermoelasticity Boundary multiphysics coupling. The
multiphysics interfaces solves for and has predefined multiphysics couplings between
the displacement and temperature field in the solid and the acoustic variations inpressure, velocity, and temperature in the fluid domain.
It can be used to, for example, model the vibrating response of MEMS devices,
including detailed description of the damping. The multiphysics interfaces are available
in 3D, 2D, and 2D axisymmetric geometries.
The functionality requires both the Acoustics Module and the MEMS Module
LUMPED SPEAKER BOUNDARY AND INTERIOR LUMPED SPEAKERBOUNDARY FOR PRESSURE ACOUSTICS, TRANSIENT

The Lumped Speaker Boundary and the Interior Lumped Speaker Boundary conditions
have been added to the Pressure Acoustics, Transient interface to model hybrid
lumped–FEM loudspeaker setups. The condition sets up couplings between theboundary condition and an Electrical Circuit interface. This makes it possible to set up
models that can include the large signal parameters like CMS(x), BL(x), or RMS(v) ina simplified way. Predefined global variables exist for the axial position and velocity.
LUMPED SPEAKER BOUNDARY AND INTERIOR LUMPED SPEAKERBOUNDARY FOR THERMOVISCOUS ACOUSTICS, FREQUENCY DOMAIN AND
TRANSIENT

The two new boundary conditions, Lumped Speaker Boundary and Interior Lumped
Speaker Boundary, have been added to Thermoviscous Acoustics in the frequency

domain and in the time domain. This completes and extends the existing conditions
available in pressure acoustics. The setup and modeling of microspeakers with hybrid
lumped–FEM representations is now simple in thermoviscous acoustics. The lumped
representations are also often accurate over a larger frequency range formicrotransducers as breakup effects occur outside the intended frequency range. In thetime domain, nonlinear effects can be included through large signal parameters like
CMS(x), BL(x), or RMS(v).
LUMPED PORT IN THERMOVISCOUS ACOUSTICS

The Lumped Port feature connects a waveguide or duct inlet or outlet to a lumped
representation element. This can be an Electrical Circuit (lumped electroacoustic
representation), a two-port network defined through a transfer matrix, or a lumped
representation of a waveguide. Basically, it couples the end of a waveguide with an
exterior system that has a given acoustic lumped representation. Several
representations and sources exist for describing the lumped system. When using the

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lumped port representation, it is assumed that only plane pressure waves — that is, the(0,0)-mode — propagate in the acoustic waveguide. The condition ensures amathematically and physically consistent coupling, including the thermoviscousboundary layers in the waveguide.
NEW CONVECTED ACOUSTIC-STRUCTURE BOUNDARY, TIME EXPLICIT
MULTIPHYSICS COUPLINGS

The new Convected Acoustic-Structure Boundary, Time Explicit and Pair Convected
Acoustic-Structure Boundary, Time Explicit multiphysics couplings are used to couple theConvected Wave Equation, Time Explicit interface with the Elastic Waves, Time
Explicit interface. The conditions are added on the boundary or pair selection between
the fluid domain and the solid domain for modeling acoustic–structure interaction(ASI) or vibroacoustic problems in the presence of a stationary background flow.
NEW FRACTURE BOUNDARY CONDITION IN ELASTIC WAVES, TIMEEXPLICIT

The new Fracture condition, available with the Elastic Waves, Time Explicit physics
interface, is used to treat two elastic domains with imperfect bonding. The fracture canbe, for example, a thin elastic layer, a fluid-filled layer, or it can be a discontinuity inelastic materials (an interior boundary). Several options exist for specifying theproperties of the thin elastic domain. Typical applications are for modelingnondestructive testing (NDT) applications, like the response of delamination regions
or other defects, or for modeling wave propagation in fractured solid media in the oiland gas industry.
PIEZOELECTRIC WAVES, TIME EXPLICIT NEWS

Improved accuracy and efficiency when solving models involving piezoelectric effects
using the time-explicit method. The performance when solving large models on acluster architecture has also been highly improved to take full advantage of the
distributed computing.
PRESSURE ACOUSTICS, TIME EXPLICIT NEWSThe Impedance conditions now use an improved numerical flux formulation forstability, ensuring that both acoustically hard and soft boundaries result in a stable
solution.
Two new conditions have also been added to model a transfer impedance setup: theInterior Impedance and the Pair Impedance conditions. Both conditions also takeadvantage of the improved numerical flux from the impedance condition.

46 |CHAPTER 1: RELEASE NOTESELASTIC WAVES, TIME EXPLICIT NEWSIn 2D models, the underlying equations have been reformulated to be more efficientfor these specific cases. In 2D models, there is now a plane strain option for the outof-plane component, which you activate by selecting the Include out-of-planecomponents check box in the 2D Approximation section. The formulation in 2D
axisymmetric models has also been improved. As an example, the number of degrees
of freedom (DOFs) solved for in the Seismic Waves Earth tutorial model have been
reduced from 17·106 to 12·106.
NEW TRANSFER MATRIX COUPLING BOUNDARY CONDITION IN
PRESSURE ACOUSTICS, FREQUENCY DOMAIN

The new Transfer Matrix Coupling boundary feature is used to couple two boundaries(source and destination) using a transfer matrix representation. The transfer matrix isa reduced or lumped representation of the physical domain, connecting the twoboundaries. The feature has two options, a so-called pointwise coupling and a lumped
representation.
EXTENDED THERMAL CONDITIONS IN THE THERMOVISCOUS BOUNDARYLAYER IMPEDANCE CONDITION

A new Thermally Conductive Wall option exists in the Thermoviscous Boundary Layer
Impedance condition. The new option makes it possible to model nonideal thermal
isothermal or adiabatic wall condition using different analytical representations of wallsof finite thickness or infinite walls.
New variables for the evaluation of the combined dissipated and transported energy(including convective terms) in the boundary layers have been added. The variables areuseful when modeling heating and not only dissipation.
SPEEDUP OF EVALUATIONS BASED ON THE KIRCHHOFF-HELMHOLTZ
KERNEL

Features that rely on the evaluation of the Kirchhoff–Helmholtz integral are now
evaluated up to 50% faster compared to the previous version (the value depends on the
hardware and the complexity of the plot — more gain is achieved as complexity
increases). This is in the Exterior Field Calculation feature that is used in pressure
acoustics for plotting the exterior field in results. In the high-frequency acoustics
interfaces — Pressure Acoustics, Asymptotic and Pressure Acoustics, KirchhoffHelmholtz — this is, in particular, important as the actual computation time lies in theevaluation of the kernel. As an example, the evaluation time of the last plot in theSubmarine Asymptotic Scattering tutorial has decreased by 25%.

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NEW POROUS LAYER IMPEDANCE OPTIONS FOR PRESSURE ACOUSTICS

The Porous Layer option in the Impedance boundary condition has been updated toinclude options to handle a certain degree of angle dependency of the impedance. The
angle of incidence can be controlled to be normal to the surface or to use a specificangle or direction. An automatic option assigns an effective angle of incidence, which
is useful when simulating, for example, room acoustics simulations with diffuse
acoustic fields.
RAY ACOUSTICS IMPROVEMENTS

Export of Balloon Data with Method Call
The Application Library model Loudspeaker Driver in a Vented Enclosure now
includes a Method and a Method Call that enable the export of the loudspeaker radiation
data (balloon plot) in a format suited for further use. This is an example of how custom
export can be made using a method and the Application Builder.

Improved Pseudorandom Number Generation
The Ray Acoustics interface includes several features that rely on pseudorandom
number generation (PRNG), such as conditional ray–boundary interaction and diffuse
or isotropic scattering at boundaries. For such features, the use of pseudorandom
number generators have been extensively reviewed and revised. The new expressions
are much less likely to incur unwanted correlations between random numbers thatshould be completely uncorrelated. This includes random boundary conditions acting
on different rays, as well as unwanted correlations between different randomly
generated vector components.

Option to Only Store Accumulated Variables in Solution
Depending on your application, the accumulated variables (such as sound pressurelevel on boundaries) might be more valuable information than the position anddirection of individual rays. To reduce file size, you now have the option to only retain
the accumulated variables in the solution while discarding the degrees of freedom
associated with the rays.

Release From Exterior Field
The Release From Exterior Field feature can now pick up exterior fields from Pressure
Acoustics, Kirchhoff Helmholtz and Pressure Acoustics, Asymptotic Scattering. Moreover,the feature now handles solving for several frequencies in a parametric sweep.

48 |CHAPTER 1: RELEASE NOTESFLOW-INDUCED NOISE IMPROVEMENTS

The excess pressure terms are now included in the Lighthill stress tensor. These
describe the deviations from linear isentropic behavior, for example, if strong nonlinear
effects occur in the source region or if a heat source is present in the flow simulation.
The Aeroacoustic Flow Source Coupling multiphysics feature now allows the source to betaken from the new Detached Eddy Simulation (DES) fluid flow interface. The Large
Eddy Simulation (LES) fluid flow interface has several new features, including a
Synthetic Turbulence option for inlets. See further details in the CFD Module release
text.
PREDEFINED PLOT SUGGESTIONS

Several predefined acoustics plots have been to the Add Predefined Plot menu in the
Results section. The new predefined plots automatically set up useful plots for several
situations:• Plots for multiphysics configurations showing the pressure or sound pressure level,
for coupled pressure and thermoviscous acoustic or pressure acoustic andporoelastic waves models.
• A plot of the cell-wave time scale, when solving models based on the discontinuous
Galerkin time-explicit formulation. This plot is useful for identifying problematicmesh regions that limit the internal time stepping.
SOLVER SUGGESTION IMPROVEMENTS

Several new iterative solver suggestions have been added and improvements have been
made to the existing generated solver suggestions. The most important are:
• For Pressure Acoustics, Frequency Domain models, the suggested iterative solver
based on the shifted Laplace method has been improved for faster convergence.
• For Thermoviscous Acoustics models, the iterative solver suggestion based on thedomain-decomposition method has been improved to use the latest solver
technology. The solver is now a good choice for solving larger models.
Solver suggestions have also been added for when you are solving 3D
vibroelectroacoustic models such as loudspeakers and other transducers. In particular,
an efficient iterative solver suggestion is given when coupling acoustics (pressure andthermoviscous acoustics), structures (solid and/or shell), and the Magnetic Fields
physics using the Lorentz Coupling or the Magnetomechanical Forces multiphysics
couplings.

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New and Updated Model Examples in 6.1
The following models are new in version 6.1:
• Prestressed Micromirror Vibrations: Thermoviscous-Thermoelasticity Coupling• One Family House Acoustics• Acoustic Microfluidic Pump
• Acoustic Streaming in a Microchannel Cross Section• Lumped Loudspeaker Driver Transient Analysis with Nonlinear Large Signal
UPDATED MODELS

The following models have been updated:• Angle Beam Nondestructive Testing: The model uses the new Fracture feature to
represent the defect.
• Flowmeter with Piezoelectric Transducers: The model now includes a backgroundflow and uses the new Pair Convected Acoustics-Elastic Waves Boundary, Time Explicit
multiphysics coupling.
• Small Concert Hall: The model includes an additional Source with Directivity featurethat imports the directivity from external data.
• Loudspeaker Driver in a Vented Enclosure: The model includes a Method andMethod Call, which make it possible to export the loudspeaker radiation data(balloon plot) in a format suited for further use.
NEW MODELS IN THE APPLICATION GALLERY ON COMSOL.COM

In addition, several models have been added to the Application Gallery, found athttps://www.comsol.com/models/acoustics-module. The new models are:• Type 4.3 Ear Simulator• Cavity Flow Noise• Electrostatic Speaker Driver• 3D Acoustic Trap and Thermoacoustic Streaming in Glass Capillary• Simple Thermoacoustic Engine• Transient Sound Pressure Level• Topology Optimization of a Sound Partition Considering Acoustic-StructureInteraction

50 |CHAPTER 1: RELEASE NOTESImportant Fixes in Version 6.1• In certain cases, a wrong sign could be used in the Perfectly Matched Boundary,leading to bad absorption performance; this has now been fixed.
• The coupling between the Thermoviscous Acoustics, Frequency Domain andTransient physics interfaces and the Shell and Layered Shell physics interfaces has
been improved. In particular, the coupling is now done to the top or bottom
displacement components instead of simply to the midplane.
• The Biot-Allard (thermal and viscous losses) option in the Poroelastic Waves physics
interface has been improved to handle low-porosity materials correctly.
• The area in the Lumped Port and Port conditions now takes symmetries into accountfor a correct scaling of transfer matrices and other area-dependent postprocessing
variables.
• The default for the Typical wave speed for perfectly matched layers values, in all the
acoustic physics interfaces, now uses a value taken from the physics (which comesfrom the material data).
• Physics symbols have been introduced for the symmetry axis in the Sector symmetry
options in the Exterior Field Calculation feature.
• The export to WAV file format now supports export with 32-bit float encoding.
In the Impulse Response plot, the 1/3 and 1/6 octave filters were slightly misaligned,
leading to small spectral errors when reconstructing the impulse response; this has
been fixed.

Backward Compatibility with Version 6.0• In Pressure Acoustics, Frequency Domain, using the Port and Lumped Port
conditions together with symmetries works automatically since version 6.0 update
2. The correct effective port area is automatically calculated and used. In version 6.0
update 1 (and earlier), an additional area scaling factor had to be added manually toa range of postprocessing variable, like the total power, volume flow, or the two-port
parameters, to get correct results. This manual scaling is no longer needed.
• An automatic calculation of the speaker area multiplication factor has been
introduced in the Lumped Speaker Boundary and Interior Lumped Speaker Boundaryfeatures in Pressure Acoustics, Frequency Domain. To retrieve the old behavior
when Use symmetries is selected, set the Speaker area multiplication factor to User
defined:ACOUSTICS MODULE|

51

model.component("comp1").physics("acpr").feature("lsb1").set("MultiplicationFactor", "UserDefined");• In Pressure Acoustics, Frequency Domain, the Porous Layer option in the Impedanceboundary condition is no longer compatible with the Anisotropic Acoustics material
model. Model the boundary condition as a domain with Poroacoustics instead.
• The default Reference pressure for the sound pressure level has changed in thePressure Acoustics interfaces; the Linearized Navier-Stokes, Frequency Domaininterface; and Linearized Potential Flow, Frequency Domain interface. To retrieve
the old behavior for interface acpr, add the following line after creating theinterface:model.component("comp1").physics("acpr").prop("cref").set("cref","343[m/s]");52 |CHAPTER 1: RELEASE NOTESBa t t e r y De s i g n Mod u l e
New Functionality in Version 6.1
GENERAL NEW FUNCTIONALITY IN THE ELECTROCHEMISTRY
INTERFACES• Fixed an issue with the Electrode Power boundary feature for the Current Distribution
Initialization study step if the dependent variable name of phis has been changed.
Also, the field name of the Lagrange multiplier has been changed to include thephysics tag. This name change may cause backward compatibility issues whenrunning the Java API.
• The Continuity Pair condition has been improved in the Primary/Secondary
Current Distribution, Lithium-Ion Battery, and Battery with Binary Electrolyte
interfaces.
• The charge settings have been moved to the new Species Properties node for the
Tertiary Current Distribution, Nernst–Planck interface.
• Nonideal activities are now supported in the Tertiary Current Distribution, Nernst–
Planck interface. Functionality has also been added for computing the nonideal
activities using the Debye–Hückel equation, based on the ionic strength of thesolution.
• For all electrochemistry interfaces, the new 0.25 V (Seawater Ag/AgCl vs. SHE) option
has been added to the Physics vs. Materials Reference Electrode Potential section of
the physics interface node.

BATTERY DESIGN MODULE|

53

NEW BATTERY-SPECIFIC FUNCTIONALITY• Added the entries Electrolyte>LiPF6 in 1:1 EC:DMC (Liquid, Li-ion Battery) andElectrode>NMC 532, LiNi0.5Mn0.3Co0.2O2 (Positive, Li-ion Battery) to the Battery
Material Library.
• New Battery Pack interface.
• New Specific Media>Battery Layers domain node in the Heat Transfer interfaces.
• Added new postprocessing variables (surface and average particle concentrations
weighted over porous material) in the Lithium-Ion and Battery with Binary
Electrolyte interfaces.
• Modified handling of the Battery Cell Capacity variable in the Lumped Battery
interface. With the new formulation, the available capacity for cycling will be
reduced as the battery capacity is reduced.
• The Parameter Estimation study step, and the BOBYQA, Levenberg-Marquardt,
and IPOPT optimization solvers are now available with a Battery Design Module
license.
• Fixed an issue with Charge-Discharge Cycling boundary node when using a Current
Distribution Initialization study step if dependent variable name of phis has beenchanged. This fix was also included in version 6.0 update 2.
ADVANCED CHEMICAL FORMULAS IN THE CHEMISTRY INTERFACE

The process of adding new chemical species, both when manually creating Speciesfeatures and when taken from Reaction features, has been significantly improved andextended.
• The Name section of a Species node now includes both the species name and thevariable name used for postprocessing. These names differ for charged species,
species with parentheses, and for species with a phase indication.
• The Species node now includes a Chemical Formula section where the composition of
the species can be defined in terms of elements from the periodic table (by selecting
the Enable formula check box). The molar mass and species charge are automaticallycomputed from the formula.
• The Chemical Formula section supports repeating units using three types of enclosing
marks: (), [], and {}. One example of this is [Al(OH)(OH2)5]^2+.
• The Chemical Formula section supports the following charge representations: ++,(++), ^(++), ^++, ^2+, (2+), and ^(2+).

54 |CHAPTER 1: RELEASE NOTES• For intricate molecular structures, a simplified (trivial) name can now be used, while
the composition and charge are detailed using the Chemical Formula input. When a
Chemical Formula is defined, it is used in place of the simplified name when balancing
a reaction formula.
• The reaction formula parser used in the Reaction node has been extended to also
support species names with repeating units and the extended set of charge
representations.
• The error messages shown for invalid species names have been improved.
IMPROVEMENTS TO THERMODYNAMICS• Constant properties defined by the Thermodynamics functionality can now be
evaluated as parameters.
• Evaluation of thermodynamic properties is now faster. Models where a significant
part of the solution time is spent evaluating functions from the Thermodynamics
functionality can now be solved in 30% less time.
The filter search field, used when adding species to a thermodynamic system, has been
improved. Filtered species can now be entered one at a time, from the top, using theEnter key. Also, it is no longer necessary to update the filter each time a species is added
to the Selected species list.
GENERAL NEW FUNCTIONALITY IN THE CHEMICAL TRANSPORTINTERFACES• The charge and molar mass settings have been moved to the new Species Properties
node for the Transport of Concentrated Species interface. Java API back comp is
provided for the charge setting commands, but not for the molar mass settingcommands.
• The charge settings have been moved to the new Species Properties node for the
Nernst–Planck Equations and Transport of Diluted Species interfaces.
• Nonideal activities are now supported in the Nernst–Planck Equations andTransport of Diluted Species interfaces. Functionality has also been added forcomputing the nonideal activities using the Debye–Hückel equation, based on theionic strength of the solution.
• Consistent stabilization is now available when using the Maxwell–Stefan diffusion
model in the Transport of Concentrated Species interface.
• The Maxwell–Stefan diffusion model can be combined with turbulent flow whenusing the Reacting Flow multiphysics interfaces.

BATTERY DESIGN MODULE|

55

• The Periodic Condition for mass transport can now be combined with wall conditions
for fluid flow when using the Reacting Flow or Reacting Flow, Diluted Species coupling
feature. In the case of turbulent flow, the wall concentration is made periodic byapplying the constraint to the wall function.
• Interior fan conditions are now supported by the Reacting Flow and Reacting Flow,
Diluted Species coupling features.
• A new Fracture feature, consistent with other features for porous media transport, is
now available. The feature includes two subnodes, Fluid and Fracture Material,
including settings for the respective phases.

New and Updated Applications and Models in Version 6.1• New Jelly roll (jelly_roll) and Jelly Roll on a Flattened Geometry(jelly_roll_flattened) tutorials.
• New Thermal Runaway Propagation in a Battery Pack(thermal_runaway_propagation) tutorial.
• New Zinc Bromine Redox Flow Battery (znbr_flow_battery) tutorial.
• The Thermal Distribution in a Pack of Cylindrical Batteries Tutorial has been
updated (and the filename has changed from lumped_li_battery_pack_6s2p tolumped_li_battery_pack_6s2p). The updated tutorial now uses the new Battery
Pack interface, which includes the potential drop in the electric conductors, and theassociated Joule heating. The model now also uses the new Battery Layers node in
the Heat Transfer interface. The meshing sequence has also been improved.
• The Liquid-Cooled Lithium-Ion Battery Pack (li_battery_pack_3d) tutorial has
now been updated to use the new Battery Layers node in Heat Transfer.
• The Lithium Battery Pack Designer (li_battery_pack_designer) app has been
updated to use the new Battery Layers node in the Heat Transfer interface.

56 |CHAPTER 1: RELEASE NOTESC AD I m po r t M od u l e, D esi gn Mod u l e,
and LiveLink™ Products for CAD
New Functionality in Version 6.1
CAD IMPORT MODULE GEOMETRY KERNEL UPGRADE

The CAD Import Module, the Design Module, and the LiveLink™ products for CAD
utilize the Parasolid® geometry kernel from Siemens PLM for solid modeling
operations, geometry repair, and defeaturing. (Without these products, a COMSOLnative geometry modeling kernel is used.) The CAD Import Module released with
COMSOL® version 6.1 includes an upgraded version of the Parasolid kernel. As aresult, a number of stability issues have been fixed, which makes geometry modeling
operations and the import of CAD models more robust.
• The CAD file import and export functionality included with these products has
been extended to support new versions for some of the supported file formats (fordetails, see under Read from File, CAD on
www.comsol.com/products/specifications/cad).
• The settings for the import of 3D CAD files now include an option to Simplify curves
and surfaces that converts, when possible, the underlying curve and surface
manifolds of the imported geometric entities to analytical form. Importing objects
with this option may improve both the performance and reliability of geometric
operations on some imported geometry.
• The defeaturing operation Delete Faces has been renamed to Replace Faces to betterreflect that new faces are created to heal the wounds after removing the faces.
• For the defeaturing operations Replace Faces (Delete Faces in version 6.0) and Detach
Faces, the heal method options Create capping faces, Extend adjacent faces, Extend
adjacent faces from child, and Extend adjacent faces from parent are equivalent to thepreviously available Fill, Patch, Patch from child, and Patch from parent, respectively.
When using the Create capping faces option, the operations can now create
replacement faces in more cases when compared to previous versions.
• The defeaturing operations Delete Fillets and Delete Holes now have the options toenter the Minimum hole radius and Minimum fillet radius, respectively, in addition to
the previously available options for entering the maximum radii for the search.

CAD IMPORT MODULE, DESIGN MODULE, AND LIVELINK™ PRODUCTS FOR CAD|

57

New Functionality in the Design Module in Version 6.1• The new Offset Faces operation enables offsetting of faces on 3D objects in thenormal direction. This functionality is especially useful when modifying geometry
imported from 3D CAD files. For example, it makes it possible to reparameterizecertain geometric features of the imported objects.
• The new Transform Faces operation enables applying a linear transform (consistingof displacement, rotation, and isotropic scaling) on a selection of faces on 3D
geometry objects. This functionality is also especially useful when modifying
geometry imported from 3D CAD files. For example, it makes it possible toreparameterize certain geometric features of the imported objects.
• The new tutorials in the Optimization of an Imported Bracket Geometry Tutorial
Series have been added to demonstrate how to use the Offset Faces and TransformFaces operations to reparameterize and optimize the size and position of throughholes on an imported geometry of a bracket.

New Functionality in LiveLink™ for AutoCAD® in Version 6.1• The LiveLink™ interface now supports AutoCAD® 2023.
• The Synchronize Offline window in the CAD software user interface now contains
a button to preview the geometries for the parameter combinations in thesynchronization request file. Use this functionality to ensure that valid geometries
will be generated and saved in the synchronization file.

New Functionality in LiveLink™ for Inventor® in Version 6.1• The LiveLink™ interface now supports Inventor® 2023.
• The Synchronize Offline window in the CAD software user interface now contains
a button to preview the geometries for the parameter combinations in thesynchronization request file. Use this functionality to ensure that valid geometries
will be generated and saved in the synchronization file.

New Functionality in LiveLink™ for PTC® Creo® Parametric™ in
Version 6.1• The LiveLink™ interface now supports PTC® Creo® Parametric™ 9.0.
• The Synchronize Offline window in the CAD software user interface now contains
a button to preview the geometries for the parameter combinations in the

58 |CHAPTER 1: RELEASE NOTES

synchronization request file. Use this functionality to ensure that valid geometries
will be generated and saved in the synchronization file.

New Functionality in LiveLink™ for Revit® in Version 6.1• The LiveLink™ interface now supports Revit® 2023.
• The new offline synchronization functionality enables synchronization when
COMSOL Multiphysics® and the CAD software cannot be run side by side on thesame computer. A synchronization file, which can contain one or several versions of
the geometry, is prepared in advance using the LiveLink add-in inside the CAD
software. The synchronization file is then loaded by the LiveLink feature in a
COMSOL ® model. Synchronization files can also be saved in response to a request
saved to file from the LiveLink feature. Offline synchronization supports parametricsweeps when using mass parameters in Revit®, and can be used on all supported
operating systems. In addition to being installed by the COMSOL installer, theLiveLink add-in is also installed by the COMSOL Client installer, available fordownload at https://www.comsol.com. Such an installation enables thefunctionality for preparing designs for synchronization, saving files for offlinesynchronization, and running simulation apps that synchronize geometry.

New Functionality in LiveLink™ for SOLIDWORKS® in Version 6.1
Starting with version 6.1 of COMSOL Multiphysics, we are no longer able to offer the
one-window interface in our LiveLink™ for SOLIDWORKS® product. LiveLink™ for
SOLIDWORKS continues to contain its bidirectional interface.

New Functionality in LiveLink™ for Solid Edge® in Version 6.1• The LiveLink™ interface now supports Solid Edge® 2023.
• The Synchronize Offline window in the CAD software user interface now contains
a button to preview the geometries for the parameter combinations in thesynchronization request file. Use this functionality to ensure that valid geometries
will be generated and saved in the synchronization file.

CAD IMPORT MODULE, DESIGN MODULE, AND LIVELINK™ PRODUCTS FOR CAD|

59

CFD Module
New Functionality in Version 6.1• Physics interfaces for Detached Eddy Simulation, a hybrid RANS-LES method,
have been added under the Single-Phase Flow section in the Fluid Flow branch. The
three new interfaces — DES RBVM, Spalart–Allmaras; DES RBVMWV, Spalart–
Allmaras; and DES Smagorinsky, Spalart–Allmaras — are applicable to threedimensional, time-dependent, single-phase, incompressible flows.
• Predefined High Mach Number, Reacting Flow multiphysics interfaces have been
added in the Chemical Species Transport branch. Physics interfaces for laminar flow,
and turbulent flow using either the k- or the Spalart–Allmaras turbulence models
are available for the transport of diluted species. The corresponding physics
interfaces for transport of concentrated species are available with a license for theChemical Reaction Engineering Module.
• The new predefined multiphysics interface, Nonisothermal Flow, Viscoelastic Flow,under the Nonisothermal Flow section in the Fluid Flow branch couples a Viscoelastic
Flow interface and a Heat Transfer in Fluids interface.
• The new predefined multiphysics interface, Two-Phase Flow, Level Set, Brinkman
Equations, under the Multiphase Flow section in the Fluid Flow branch couples a
Brinkman Equations interface and a Level Set in Porous Media interface using the
Two-Phase Flow, Level Set multiphysics coupling node. It also adds a Wetted Wallmultiphysics feature.
• New multiphysics interfaces, Dispersed Two-Phase Flow with Species Transport, arenow available in the Chemical Species Transport branch for laminar flow, andturbulent flow using either the k-, k-, Low Re k-, or SST model. These couplea Mixture Model interface, Continuous Phase Transport of Diluted Species
interface, and Dispersed Phase Transport of Diluted Species interface using theDispersed Two-Phase Flow, Diluted Species multiphysics coupling node.
• The new predefined multiphysics interface, Solid Thin Film Damping, for modeling
fluid-induced damping in solid structures, is now available under the Fluid-StructureInteraction section in the Structural Mechanics branch. It couples a Solid Mechanics
interface and a Thin-Film Flow interface using the Structure Thin-Film Flow
Interaction multiphysics coupling node.
• All transport-equation RANS turbulence models, except for the Spalart–Allmaras
model, are now applicable in porous media domains. There are three options for the

60 |CHAPTER 1: RELEASE NOTESPorous medium turbulence model: the Nakayama–Kuwahara, Pedras–de Lemos, and a
Default option, which combines the other two models.

• For the Large Eddy Simulation and Detached Eddy Simulation interfaces, the Inlet
condition has a new option, Include synthetic turbulence, for generating
spatiotemporal velocity fluctuations based on a model energy spectrum.
• The new Thin Barrier node in the Multiphase Flow in Porous Media multiphysics
interface makes it possible to add thin layers that act as a resistance for the flow fieldsof all phases without meshing through the layer’s thickness.
• Laminar-to-turbulent boundary layer transition can be modeled by enabling the
new Include transition modeling option in the Turbulent Flow, SST interface.
• The Mixture Model multiphysics coupling node in the Phase Transport, Mixture
Model multiphysics interface has a new Include bubble-induced turbulence option in
the Turbulence section. This option is available for all two-equation turbulencemodels when the Dispersed phase in the Physical Model section is set to Liquid
droplets/bubbles.
• The Two-Phase Flow, Level Set; Two-Phase Flow, Phase Field; and Three-Phase Flow,
Phase Field multiphysics couplings have a new option to get the effective material
properties from a Multiphase Material node with built-in mixing rules. This isespecially effective when coupling these multiphysics interfaces with other physics,
such as heat transfer or electrostatics, since the multiphase material will use
appropriate mixing rules for nonfluid material properties. In older versions, thiswould require you to write user-defined expressions based on the volume fractionof each fluid phase to compute the effective material properties used in each physics
interface.
• Dedicated material property groups have been added for all available inelastic nonNewtonian models. The material property group contains all necessary material
parameters and the apparent viscosity expression. It picks up the shear rate from thefluid flow interface to define the dynamic viscosity in the Basic (def) material modelby means of a synchronization rule. Thus, an inelastic non-Newtonian model can beselected directly by adding the corresponding Material Properties group as a subnodeto a material node.
• The Thin-Film Flow, Shell (tffs) and Thin-Film Flow, Edge (tffs) interfaces havebeen renamed Thin-Film Flow (tff). Similarly, the Phase Field, Thin-Film Flow,
Shell (pftffs), and Phase Field, Thin-Film Flow, Edge (pftffs) interfaces have beenrenamed Phase Field, Thin-Film Flow (pftff). Moreover, the Two-Phase Thin-Film
Flow, Shell, Phase Field and Two-Phase Thin-Film Flow, Edge, Phase Fieldinterfaces have been renamed Two-Phase Thin-Film Flow, Phase Field.

CFD MODULE|

61

New and Updated Models in Version 6.1
Several applications using the Two-Phase Flow, Level Set; Two-Phase Flow, Phase
Field; or Three-Phase Flow, Phase Field interface have been updated to include a
Multiphase Material to compute the effective material properties from volume fractions
and the material properties of each phase.
RESIN TRANSFER MOLDING OF A WIND TURBINE BLADE

This example shows the modeling of a resin transfer molding (RTM) process for a windturbine blade using the Two-Phase Flow, Level Set, Brinkman Equations interface.
Resin is injected into a preform consisting of different composites with different
anisotropic permeabilities.

Backward Compatibility with Version 6.0 and Earlier
RENAMED THIN-FILM FLOW AND PHASE FIELD, THIN-FILM FLOWINTERFACES IN COMPILED JAVA FILES

Compiled Java files using the Thin-Film Flow, Shell (tffs) and Thin-Film Flow, Edge(tffs) interfaces need to be updated manually to run in version 6.1. The identifier forthese interfaces has been changed to tff. In order to run Java files, you need to replace
all instances of tffs with tff.
Similarly, the identifier for the Phase Field, Thin-Film Flow, Shell (pftffs), and Phase
Field, Thin-Film Flow, Edge (pftffs) needs to be manually changed from pftffs topftff.
NON-NEWTONIAN INELASTIC MATERIAL MODELS

Non-Newtonian inelastic material models that were added in older versions will not beable to define the dynamic viscosity in the Basic (def) material model.
THE LES SMAGORINSKY INTERFACE

The modeled subgrid stress term in the LES Smagorinsky interface has been recast on
symmetric form and the filtering is now instead included in the expression for the
turbulent viscosity. The Smagorinsky parameter now enters the turbulent viscosity
expression as squared, and its default value has therefore been changed to 0.1. Slightdifferences in the results may occur for some models.

62 |CHAPTER 1: RELEASE NOTESBackward Compatibility with Version 5.6 and Earlier
BRINKMAN EQUATIONS, FREE AND POROUS MEDIA FLOW AND DARCY’S
LAWWhen opening a model created in version 5.6 or earlier, the old Fluid and Matrix
Properties feature is not migrated, but a warning message is prompted. This feature

should be manually replaced by the new Porous Medium feature (which adds Porous
Matrix and Fluid subfeatures) to allow an updated definition of the material properties.
Support for obsolete features is not ensured in future versions; thus it is strongly
recommended to transfer the old feature to the new feature.

Backward Compatibility with Version 5.5 and Earlier
TURBULENT INTENSITY AND TURBULENCE LENGTH SCALE

The new default value for Turbulent intensity is the same as the old default value,
whereas the new Geometry based default value in general will differ from the old one.
Old Java files with default values for Turbulence length scale should add the line,
model.component("comp1").physics("spf").feature("inl1").
set("LT_list", "user_defined");in the Model Java-file to retrieve the old length scale.
EULER-EULER MODEL

Results from models using the Mass Transfer feature in the Euler-Euler Modelinterfaces may differ in version 5.6 due to the improved momentum conservation.
PHASE TRANSPORT, MIXTURE MODEL

Because the Phase Transport, Mixture Model interfaces have been revised using a
mass-averaged formulation to support compressible mixture flows, models built inversion 5.5 can return slightly different results when run in version 5.6.
TWO-PHASE FLOWIn the Level Set and Phase Field interfaces, the Initial Interface feature is now obsolete.
It does not need to be replaced because the phase interfaces are automatically detectedfrom the selection of the Initial Values features, and the initial distribution of the levelset or phase field function is solved for in the Phase Initialization study step.

CFD MODULE|

63

Chemical Reaction Engineering
ModuleNew Functionality in Version 6.1
SHRINKING CORE MODEL FOR PACKED BEDS

The Packed Bed feature in the Transport of Diluted Species interface now includes theshrinking core model. Use this model to describe situations where a solid particle isconsumed and shrinks, leaving an outer porous layer, and an inner shrinking core. The
core consuming reactions, the transport and reactions in the porous layer, as well as
the interparticle mass transfer can be studied in detail.
The shrinking core model is enabled using the new Pellet Type setting in the Pellets
subnode of the Packed Bed node. A new Transport of Diluted Species, Shrinking Core
Model entry s also available under the Reacting Flow in Porous Media interface in the
Model Wizard and the Add Physics window.
DISPERSED TWO-PHASE FLOW WITH SPECIES TRANSPORT

A new multiphysics interface, Dispersed Two-Phase Laminar Flow with Species
Transport, is now available for modeling two-phase flow coupled with chemical species
transport. A liquid containing a dispersed phase (droplets or bubbles) is modeled usinga Mixture Model interface. Mass transport of solutes in each phase, as well as solute
extraction between the phases, can be solved for. Turbulent flow versions of themultiphysics interface are available with a license for either the CFD Module or theHeat Transfer Module.
The Mixture Model, Laminar Flow interface is now available with a license for theChemical Reaction Engineering Module.

64 |CHAPTER 1: RELEASE NOTESADVANCED CHEMICAL FORMULAS IN THE REACTION ENGINEERING AND
CHEMISTRY INTERFACES

The process of adding new chemical species, both when manually creating Speciesfeatures and when taken from Reaction features, has been significantly improved andextended.
• The Name section of a Species node now includes both the species name and thevariable name used for postprocessing. These names differ for charged species,
species with parentheses, and for species with a phase indication.
• The Species node now includes a Chemical Formula section where the composition of
the species can be defined in terms of elements from the periodic table (by selecting
the Enable formula check box). The molar mass and species charge are automaticallycomputed from the formula.
• The Chemical Formula section supports repeating units using three types of enclosing
marks: (), [], and {}. One example of this is [Al(OH)(OH2)5]^2+.
• The Chemical Formula section supports the following charge representations: ++,(++), ^(++), ^++, ^2+, (2+), and ^(2+).
• For intricate molecular structures, a simplified (trivial) name can now be used, while
the composition and charge are detailed using the Chemical Formula input. When a
Chemical Formula is defined, it is used in place of the simplified name when balancing
a reaction formula.
• The reaction formula parser used in the Reaction node has been extended to also
support species names with repeating units and the extended set of charge
representations.
• The error messages shown for invalid species names have been improved.
NEW FRACTURE FEATURE FOR TRANSPORT OF DILUTED SPECIES IN
FRACTURES

A new Fracture feature, consistent with other features for porous media transport, is
now available. The feature includes two subnodes, Fluid and Fracture Material,
including settings for the respective phases.
NEW HIGH MACH NUMBER REACTING FLOW MULTIPHYSICS INTERFACES

The new High Mach Number Reacting Flow multiphysics interface is available forusers with licenses for both the CFD Module and the Chemical Reaction Engineering
Module.

CHEMICAL REACTION ENGINEERING MODULE|

65

The new High Mach Number Reacting Flow, Diluted Species multiphysics interface isavailable for users with a license for the CFD Module.
POSTPROCESSING FUNCTIONALITY• It is now possible to place line graph legends outside of the graph axis area. This isuseful for avoiding that graph lines are covered by the legend when plotting many
curves in the same graph.
• An extended color cycle, including 19 colors, is now available for graph plots.
• A new Pellets plot is available for visualizing the concentration inside porous pellets(or similar particles) of a packed bed. Spheres or three orthogonal filled circles canbe used to visualize the concentration in 3D and 2D plot groups.
NEW AND IMPROVED FUNCTIONALITY• Evaluation of thermodynamic properties is now faster. Models where a significant
part of the solution time is spent evaluating functions from the Thermodynamics
functionality can now be solved in 30% less time.
• The molar mass definition is now synchronized by the Species Matching section in
the Chemistry interface. Selecting a species solved for, the molar mass in thecorresponding mass transport interface is updated to the one defined in Chemistry.
• Definitions of postprocessing variables available in the Transport of Diluted Species
interface have been added to the documentation.
• Constant properties defined by the Thermodynamics functionality can now be
evaluated as parameters.
• The molar mass and charge settings have been moved to the new Species Properties
node for the Transport of Concentrated Species interface. The node is named
Species Molar Mass when Migration in electric field is not selected. Java API backward
compatibility is provided for the charge setting commands, but not for the molar
mass setting commands.
• The charge settings have been moved to the new Species Properties node for theTransport of Diluted Species, and the Nernst–Planck Equations interfaces. The
node is named Species Charges when ideal species activities are used.
• Nonideal activities are now supported in the Nernst–Planck Equations andTransport of Diluted Species interfaces. Functionality has also been added forcomputing the nonideal activities using the Debye–Hückel equation, based on theionic strength of the solution.

66 |CHAPTER 1: RELEASE NOTES• When importing reactions from a CHEMKIN file, separate Species nodes are now
also created for species that does not occur in the reactions.
• Consistent stabilization is now available when using the Maxwell-Stefan diffusion
model in the Transport of Concentrated Species interface.
• The Maxwell-Stefan diffusion model can be combined with turbulent flow whenusing the Reacting Flow multiphysics interfaces.
• The Periodic Condition for mass transport can now be combined with wall conditions
for fluid flow when using the Reacting Flow or Reacting Flow, Diluted Species coupling
feature. In the case of turbulent flow, the wall concentration is made periodic byapplying the constraint to the wall function.
• Interior fan conditions are now supported by the Reacting Flow and Reacting Flow,
Diluted Species coupling features.
• A new Adsorption/Desorption of bulk species check box is available in the Adsorbed
Species section in the Porous Catalyst feature.
• Separate species are now used in the solver sequence for adsorbed species andsurface species (defined by the Porous Catalyst and Packed Bed features). This meansthat individual settings can be applied to the variables in the solver sequence.
• It is now possible to add user-defined contributions to the equations for pellet masstransport in a Packed Bed feature. To do so, use the Show More Options window andselect the Equation-Based Contributions check box under Physics. Settings for thepellet extra dimension are available in features for user-defined contributions, suchas the Weak Contribution node, when selecting Attached Dimensions for the selection.
• The filter search field, used when adding species to a thermodynamic system, hasbeen improved. Filtered species can now be entered one at a time, from the top,
using the Enter key. Also, it is no longer necessary to update the filter each time a
species is added to the Selected species list.

New Models in Version 6.1
CONTINUOUS MIXERThis model simulates a tank with an asymmetrically positioned impeller. The tank and
impeller geometry are defined using parts from the Mixer Module Part Library. A
liquid is continuously fed into the tank near the top and exits through an outlet at thebottom. The turbulent flow field resulting from the impeller agitation is solved forusing a frozen-rotor analysis. The model shows how to visualize the mixing andcompute the residence-time distribution using particle tracing. A pulse containing

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50,000 massless particles is injected and tracked as it flows through the mixer. The
residence-time distribution is computed by counting the number of particles that havereached the outlet.
CRYSTALLIZATION OF BENZOIC ACID IN A MIXED SUSPENSION, MIXEDPRODUCT REMOVAL CRYSTALLIZER

Crystallization is a key separation process in pharmaceuticals production, for example.
It is the process by which a chemical species is separated from solution by forming acrystal. To achieve the required product properties, control over the crystal particle
size distribution is necessary. This 0D model implements a population balance
equation to determine the crystal size distribution and mean particle size for benzoic
acid crystallizing in a mixed-suspension, mixed-product-removal crystallizer.
EVAPORATION OF ETHANOL AND WATER FROM A WINE GLASS

During professional wine tastings, several samples of wine are judged in one session. It
is important that each sample is covered since evaporation of ethanol and water willchange the taste. This model simulates the evaporation of ethanol and water from awine glass. Evaporation of multiple species from a nonideal liquid mixture is modeledusing the extended Raoult’s law. The evaporation induces free convection in thesurrounding vapor phase, both due to the change in composition and due to the heatof vaporization. The model is set up in 2D axisymmetry using coupled Laminar Flow,
Transport of Concentrated Species, and Heat Transfer in Fluids interfaces. Accurate
thermodynamic data is provided by the Thermodynamics functionality.

Updated Models in Version 6.1
SYNGAS COMBUSTION IN A ROUND-JET BURNER

The model has been updated to use a gas phase thermodynamic system (under the
Thermodynamics node). Thermodynamics properties and transport properties of thegas mixture are automatically defined by a Chemistry interface, eliminating the needfor interpolation functions.
POROUS CATALYTIC REACTOR WITH INJECTION NEEDLE

The model has been substantially reworked to illustrate the modeling of a porous
catalytic reactor for hydrogen oxidation on a noble metal Rh catalyst dispersed on analumina support (Rh/Al2O3). The surface reaction kinetics in the reactor are
implemented using a Porous Catalyst feature. Adsorption and desorption of bulk

68 |CHAPTER 1: RELEASE NOTES

species as well as the development of surface species attached to the catalyst are solved
for.
DRUG RELEASE FROM A BIOMATERIAL MATRIXThe model uses a single Transport of Diluted Species in Porous Catalysts interface tostudy drug release from a biomaterial matrix into damaged cell tissue. The surface
species kinetics in the biomaterial is modeled using a Porous Catalyst feature.

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Composite Materials Module
New Functionality in Version 6.1
IMPROVED CONTACT FUNCTIONALITYThe Contact node in the Layered Shell interface is improved, and is now similar toother physics interfaces.
Two new formulations have been added, Penalty, dynamic and Augmented Lagrangian,
dynamic, which are essential for modeling dynamic contact events. The Friction, Slip
Velocity, Adhesion, and Decohesion subnodes are now available for modeling different
contact phenomena efficiently.
The Source external to current physics check box has been removed, and contact with
objects outside of the interface is now handled automatically. If a contact pair is present
in the model, then a default Contact feature is automatically added.
PERFORMANCE IMPROVEMENT IN LAYERED LINEAR ELASTIC MATERIAL

When the Layered Material Link or Layered Material Stack material type contains
transformations of symmetry, antisymmetry, or repetition types, the symmetry
properties of the structure are employed to speed up the generation of matrices as longas the middle layer is not merged. A combination of numerical and analytical extra
dimension integration is used to compute the stiffness matrix in the Layered Linear
Elastic material. This improvement applies to the Layered Linear Elastic Material node
when there is a single product selection in the Shell and Membrane interfaces andwhen weak equations are written in terms of the section forces. As a result of thisimprovement, assembly time and computation time are significantly reduced.
MULTIPLICATIVE DECOMPOSITION IN THE LAYERED LINEAR ELASTIC
MATERIAL• In the Shell interface, the Layered Linear Elastic Material node now supports themultiplicative decomposition of strains. This formulation is important in the case offinite deformations, and it is now the default for geometric nonlinear analyses.
• The Automatic option in the Shear Correction Factor section sets the shear correction
factors to 5/6. The new Based on 3D elasticity theory option can restore the oldbehavior of the Automatic option.

70 |CHAPTER 1: RELEASE NOTESNEW OPERATORS IN LAYERED MATERIALSNew physics-scoped operators have been added to the Layered Shell interface and to
the layered materials in the Shell and Membrane interfaces. These operators help tocompute the integration, average, or summation of variables over layers or interfaces
in the thickness direction.
REDUCED NUMBER OF DEFAULT PLOTS

For details, see Reduced Number of Default Plots in the release notes for the Structural
Mechanics Module.
MISCELLANEOUS• The Add Material button in the Layered Linear Elastic Material node in the Shellinterface is now consistent with the same button available in other layered features.
• The length scale factor (LSF) variable in the Layered Shell interface is now definedin the edge product selection, which gives the correct through-thickness variation.
• The reaction force and moment variables in the Layered Shell interface are available
in lower dimensions. The total reaction force and moments are corrected for theContinuity node.
• In the Safety node under Layered Linear Elastic Material, the mode C index for Puck
failure criterion is corrected. The safety factor are now nonnegative for the Puck and
LaRC03 criteria.
The layers’ thickness are correctly used to compute the initial stresses from section
forces in the Initial Stress and Strain subnode under the Layered Linear Elastic Material
node in the Membrane interface.

New Models in Version 6.1
MICROMECHANICS OF FAILURE: MULTISCALE ANALYSIS OF ACOMPOSITE STRUCTURE

In this example, the structural integrity of a cylinder made by a fiber composite isassessed both at the macroscale and microscale levels.
Analyses both at the macroscale and microscale, so-called multiscale analyses, offer anin-depth insight into the composite structure as well as its constituent’s response. They
also help you to study the micromechanics of failure based on the global scale loading.

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Corrosion Module
New Functionality in Version 6.1
GENERAL NEW FUNCTIONALITY IN THE ELECTROCHEMISTRY
INTERFACES• Fixed an issue with the Electrode Power boundary feature for the Current Distribution
Initialization study step if the dependent variable name of phis has been changed.
Also, the field name of the Lagrange multiplier has been changed to include thephysics tag. The name change may cause backward compatibility issues whenrunning the Java API.
• The Continuity Pair condition has been improved in the Primary/Secondary
Current Distribution and Cathodic Protection interfaces.
• The charge settings have been moved to the new Species Properties node for the
Tertiary Current Distribution, Nernst–Planck interface.
• Nonideal activities are now supported in the Tertiary Current Distribution, Nernst–
Planck interface. Functionality has also been added for computing the nonideal
activities using the Debye–Hückel equation, based on the ionic strength of thesolution.
• The new 0.25 V (Seawater Ag/AgCl vs. SHE) option has been added to the Physics vs.
Materials Reference Electrode Potential section of the physics interface node for all
electrochemistry interfaces.
NEW CORROSION MODULE-SPECIFIC FUNCTIONALITY

A new Sacrificial Anode Surface boundary node is now available under the Cathodic
Protection Surfaces node in the Cathodic Protection and Secondary Current
Distribution interfaces.
ADVANCED CHEMICAL FORMULAS IN THE CHEMISTRY INTERFACE

The process of adding new chemical species, both when manually creating Speciesfeatures, and when taken from Reaction features, has been significantly improved andextended.
• The Name section of a Species node now includes both the species name and thevariable name used for postprocessing. These names differ for charged species,
species with parentheses, and for species with a phase indication.

72 |CHAPTER 1: RELEASE NOTES• The Species node now includes a Chemical Formula section where the composition of
the species can be defined in terms of elements from the periodic table (by selecting
the Enable formula check box). The molar mass and species charge are automaticallycomputed from the formula.
• The Chemical Formula section supports repeating units using three types of enclosing
marks: (), [], and {}. On example of this is [Al(OH)(OH2)5]^2+.
• The Chemical Formula section supports the following charge representations: ++,(++), ^(++), ^++, ^2+, (2+), and ^(2+).
• For intricate molecular structures, a simplified (trivial) name can now be used, while
the composition and charge are detailed using the Chemical Formula input. When a
Chemical Formula is defined, it is used in place of the simplified name when balancing
a reaction formula.
• The reaction formula parser used in the Reaction node has been extended to also
support species names with repeating units and the extended set of charge
representations.
• The error messages shown for invalid species names have been improved.
GENERAL NEW FUNCTIONALITY IN THE CHEMICAL TRANSPORTINTERFACES• The charge settings have been moved to the new Species Properties node for the
Nernst–Planck Equations and Transport of Diluted Species interfaces.
• Nonideal activities are now supported in the Nernst–Planck Equations andTransport of Diluted Species interfaces. Functionality has also been added forcomputing the nonideal activities using the Debye–Hückel equation, based on theionic strength of the solution.
• The Periodic Condition for mass transport can now be combined with wall conditions
for fluid flow when using the Reacting Flow, Diluted Species coupling feature. In thecase of turbulent flow, the wall concentration is made periodic by applying theconstraint to the wall function.
• Interior fan conditions are now supported by the Reacting Flow and Reacting Flow,
Diluted Species coupling features.
• A new Fracture feature, consistent with other features for porous media transport, is
now available. The feature includes two subnodes, Fluid and Fracture Material,
including settings for the respective phases.

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New and Updated Models in Version 6.1• New Atmospheric Corrosion with Mass Transport(atmospheric_corrosion_mass_transport) tutorial.
• New Corrosion Inhibitor Transport (corrosion_inhibitor_transport) tutorial.
• New Alternating Current-Induced Corrosion (ac_corrosion) tutorial.

74 |CHAPTER 1: RELEASE NOTESECAD Import Module
New Functionality in Version 6.0
The ECAD Import Module includes two new options for ignoring unnecessary
vertices, thereby eliminating short edges when generating the 2D geometries from thelayouts imported from IPC-2581, ODB++, and GDS files. When importing any ofthese file formats, the settings for the import now include, in the new Ignore vertices
in layers section, the Ignore vertices with continuous tangent and Eliminate short edges
check boxes.

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Electrochemistry Module
New Functionality in Version 6.1
GENERAL NEW FUNCTIONALITY IN THE ELECTROCHEMISTRY
INTERFACES• Fixed an issue with the Electrode Power boundary feature for the Current Distribution
Initialization study step if the dependent variable name of phis has been changed.
Also, the field name of the Lagrange multiplier has been changed to include thephysics tag. The name change may cause backward compatibility issues whenrunning the Java API.
• The Continuity pair condition has been improved in the Primary/Secondary
Current Distribution interfaces.
• The charge settings have been moved to the new Species Properties node for the
Tertiary Current Distribution, Nernst–Planck interface.
• Nonideal activities are now supported in the Tertiary Current Distribution, Nernst–
Planck interface. Functionality has also been added for computing the nonideal
activities using the Debye–Hückel equation, based on the ionic strength of thesolution.
• The new 0.25 V (Seawater Ag/AgCl vs. SHE) option has been added to the Physics vs.
Materials Reference Electrode Potential section of the physics interface node in allelectrochemistry interfaces.
ADVANCED CHEMICAL FORMULAS IN THE CHEMISTRY INTERFACE

The process of adding new chemical species, both when manually creating Speciesfeatures and when taken from Reaction features, has been significantly improved andextended.
• The Name section of a Species node now includes both the species name and thevariable name used for postprocessing. These names differ for charged species,
species with parentheses, and for species with a phase indication.
• The Species node now includes a Chemical Formula section where the composition of
the species can be defined in terms of elements from the periodic table (by selecting
the Enable formula check box). The molar mass and species charge are automaticallycomputed from the formula.

76 |CHAPTER 1: RELEASE NOTES• The Chemical Formula section supports repeating units using three types of enclosing
marks: (), [], and {}. On example of this is [Al(OH)(OH2)5]^2+.
• The Chemical formula section supports the following charge representations: ++,(++), ^(++), ^++, ^2+, (2+), and ^(2+).
• For intricate molecular structures, a simplified (trivial) name can now be used, while
the composition and charge are detailed using the Chemical Formula input. When a
Chemical Formula is defined, it is used in place of the simplified name when balancing
a reaction formula.
• The reaction formula parser used in the Reaction node has been extended to also
support species names with repeating units and the extended set of charge
representations.
• The error messages shown for invalid species names have been improved.
GENERAL NEW FUNCTIONALITY IN THE CHEMICAL TRANSPORTINTERFACES• The charge settings have been moved to the new Species Properties node for the
Nernst–Planck Equations and Transport of Diluted Species interfaces.
• Nonideal activities are now supported in the Nernst–Planck Equations andTransport of Diluted Species interfaces.
• The Periodic Condition for mass transport can now be combined with wall conditions
for fluid flow when using the Reacting Flow or Reacting Flow, Diluted Species coupling
feature. In the case of turbulent flow, the wall concentration is made periodic byapplying the constraint to the wall function.
• Interior fan conditions are now supported by the Reacting Flow, and the Reacting
Flow, Diluted Species coupling features.
• A new Fracture feature, consistent with other features for porous media transport, is
now available. The feature includes two subnodes, Fluid and Fracture Material,
including settings for the respective phases.

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77

Electrodeposition Module
New Functionality in Version 6.1
GENERAL NEW FUNCTIONALITY IN THE ELECTROCHEMISTRY
INTERFACES• Fixed an issue with the Electrode Power boundary feature for the Current Distribution
Initialization study step if the dependent variable name of phis has been changed.
Also, the field name of the Lagrange multiplier has been changed to include thephysics tag. The name change may cause backward compatibility issues whenrunning the Java API.
• The Continuity Pair condition has been improved in the Primary/Secondary
Current Distribution interfaces.
• The charge settings have been moved to the new Species Properties node for the
Tertiary Current Distribution, Nernst–Planck interface.
• Nonideal activities are now supported in the Tertiary Current Distribution, Nernst–
Planck interface. Functionality has also been added for computing the nonideal
activities using the Debye–Hückel equation, based on the ionic strength of thesolution.
• The new 0.25 V (Seawater Ag/AgCl vs. SHE) option has been added to the Physics vs.
Materials Reference Electrode Potential section of the physics interface node in allelectrochemistry interfaces
ADVANCED CHEMICAL FORMULAS IN THE CHEMISTRY INTERFACE

The process of adding new chemical species, both when manually creating Speciesfeatures, and when taken from Reaction features, has been significantly improved andextended.
• The Name section of a Species node now includes both the species name and thevariable name used for postprocessing. These names differ for charged species,
species with parentheses, and for species with a phase indication.
• The Species node now includes a Chemical Formula section where the composition of
the species can be defined in terms of elements from the periodic table (by selecting
the Enable formula check box). The molar mass and species charge are automaticallycomputed from the formula.

78 |CHAPTER 1: RELEASE NOTES• The Chemical Formula section supports repeating units using three types of enclosing
marks: (), [], and {}. On example of this is [Al(OH)(OH2)5]^2+.
• The Chemical Formula section supports the following charge representations: ++,(++), ^(++), ^++, ^2+, (2+), and ^(2+).
• For intricate molecular structures, a simplified (trivial) name can now be used, while
the composition and charge are detailed using the Chemical Formula input. When a
Chemical Formula is defined, it is used in place of the simplified name when balancing
a reaction formula.
• The reaction formula parser used in the Reaction node has been extended to also
support species names with repeating units and the extended set of charge
representations.
• The error messages shown for invalid species names have been improved.
GENERAL NEW FUNCTIONALITY IN THE CHEMICAL TRANSPORTINTERFACES• The charge settings have been moved to the new Species Properties node for the
Nernst–Planck Equations and Transport of Diluted Species interfaces.
• Nonideal activities are now supported in the Nernst–Planck Equations andTransport of Diluted Species interfaces. Functionality has also been added forcomputing the nonideal activities using the Debye–Hückel equation, based on theionic strength of the solution.
• The Periodic Condition for mass transport can now be combined with wall conditions
for fluid flow when using the Reacting Flow or Reacting Flow, Diluted Species coupling
feature. In the case of turbulent flow, the wall concentration is made periodic byapplying the constraint to the wall function.
• Interior fan conditions are now supported by the Reacting Flow and Reacting Flow,
Diluted Species coupling features.
• A new Fracture feature, consistent with other features for porous media transport, is
now available. The feature includes two subnodes, Fluid and Fracture Material,
including settings for the respective phases.

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Fatigue Module
New Functionality in Version 6.1
RANDOM VIBRATION IMPROVEMENT

A Life cutoff input has been added to the Random Vibration node. It is used to facilitate
the visualization of fatigue life so that extremely long lifetimes can be removed.

80 |CHAPTER 1: RELEASE NOTES

Fuel Cell & Electrolyzer Module
New Functionality in Version 6.1
GENERAL NEW FUNCTIONALITY IN THE ELECTROCHEMISTRY
INTERFACES• Fixed an issue with the Electrode Power boundary feature for the Current Distribution
Initialization study step if the dependent variable name of phis has been changed.
Also, the field name of the Lagrange multiplier has been changed to include thephysics tag. The name change may cause backward compatibility issues whenrunning the Java API.
• The Continuity Pair condition has been improved in the Primary/Secondary
Current Distribution interfaces.
• The charge settings have been moved to the new Species Properties node for the
Tertiary Current Distribution, Nernst–Planck interface.
• Nonideal activities are now supported in the Tertiary Current Distribution, Nernst–
Planck interface. Functionality has also been added for computing the nonideal
activities using the Debye–Hückel equation, based on the ionic strength of thesolution.
• The new 0.25 V (Seawater Ag/AgCl vs. SHE) option has been added to the Physics vs.
Materials Reference Electrode Potential section of the physics interface node in allelectrochemistry interfaces.
NEW FUEL CELL AND ELECTROLYZER-SPECIFIC FUNCTIONALITY• A Consistent Stabilization section has been added to the settings for gas-phasediffusion equations in the Hydrogen Fuel Cell and Water Electrolyzer interfaces.
• The default solver generation for 3D models using the Hydrogen Fuel Cell and theWater Electrolyzer interfaces has been significantly improved, with the default
generated solver depending on the physics settings and the number of degrees of
freedom. For large problems, Algebraic Multigrid iterative solvers are now generated
by default, which typically reduces memory usage and computational time
considerably.
• Correction of the normal boiling value of H2O species in the Hydrogen Fuel Celland Water Electrolyzer interfaces. This update affects the built-in thermal

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81

conductivity value calculated by the interface. This fix was also included in version
6.0 update 2.
• A new Auxiliary Species option was added to the Hydrogen Fuel Cell and Water
Electrolyzer interfaces. This provides the possibility to add an arbitrarily definedgaseous species on the O2 and/or H2 sides.
• Improved formulation of the mass flow rates boundary condition using the Total
mass flow rate option in the Hydrogen Fuel Cell and Water Electrolyzer interfaces.
The new formulation is used for the species-dependent variables for the case whengas-phase diffusion is active in combination with Darcy’s law.
ADVANCED CHEMICAL FORMULAS IN THE CHEMISTRY INTERFACE

The process of adding new chemical species, both when manually creating Speciesfeatures and when taken from Reaction features, has been significantly improved andextended.
• The Name section of a Species node now includes both the species name and thevariable name used for postprocessing. These names differ for charged species,
species with parentheses, and for species with a phase indication.
• The Species node now includes a Chemical Formula section where the composition of
the species can be defined in terms of elements from the periodic table (by selecting
the Enable formula check box). The molar mass and species charge are automaticallycomputed from the formula.
• The Chemical Formula section supports repeating units using three types of enclosing
marks: (), [], and {}. On example of this is [Al(OH)(OH2)5]^2+.
• The Chemical Formula section supports the following charge representations: ++,(++), ^(++), ^++, ^2+, (2+), and ^(2+).
• For intricate molecular structures, a simplified (trivial) name can now be used, while
the composition and charge are detailed using the Chemical Formula input. When a
Chemical Formula is defined, it is used in place of the simplified name when balancing
a reaction formula.
• The reaction formula parser used in the Reaction node has been extended to also
support species names with repeating units and the extended set of charge
representations.
• The error messages shown for invalid species names have been improved.

82 |CHAPTER 1: RELEASE NOTESIMPROVEMENTS TO THERMODYNAMICS• Constant properties defined by the Thermodynamics functionality can now be
evaluated as parameters.
• Evaluation of thermodynamic properties is now faster. Models where a significant
part of the solution time is spent evaluating functions from the Thermodynamics
functionality can now be solved in 30% less time.
• The filter search field, used when adding species to a thermodynamic system, hasbeen improved. Filtered species can now be entered one at a time, from the top,
using the Enter key. Also, it is no longer necessary to update the filter each time a
species is added to the Selected species list.
GENERAL NEW FUNCTIONALITY IN THE CHEMICAL TRANSPORTINTERFACES• The charge and molar mass settings have been moved to the new Species Properties
node for the Transport of Concentrated Species interface. Java API backward compis provided for the charge setting commands, but not for the molar mass settingcommands.
• The charge settings have been moved to the new Species Properties node for the
Nernst–Planck Equations and Transport of Diluted Species interfaces.
• Nonideal activities are now supported in the Nernst–Planck Equations andTransport of Diluted Species interfaces. Functionality has also been added forcomputing the nonideal activities using the Debye–Hückel equation, based on theionic strength of the solution.
• Consistent stabilization is now available when using the Maxwell-Stefan diffusion
model in the Transport of Concentrated Species interface.
• The Maxwell-Stefan diffusion model can be combined with turbulent flow whenusing the Reacting Flow multiphysics interfaces.
• The Periodic Condition boundary condition for mass transport can now be combinedwith wall conditions for fluid flow when using the Reacting Flow or Reacting Flow,
Diluted Species coupling feature. In the case of turbulent flow, the wall concentration
is made periodic by applying the constraint to the wall function.
• Interior fan conditions are now supported by the Reacting Flow and Reacting Flow,
Diluted Species coupling features.
• A new Fracture feature, consistent with other features for porous media transport, is
now available. The feature includes two subnodes, Fluid and Fracture Material,
including settings for the respective phases.

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New and Updated Models in Version 6.1• A new Fuel Cell Stack Cooling (stack_cooling) tutorial has been added.

84 |CHAPTER 1: RELEASE NOTESGeomechanics Module
New Functionality in Version 6.1
ENHANCEMENTS TO PLASTICITY• The Plasticity, Elastoplastic Soil, Soil Plasticity, Rocks, and Concrete nodes now havean Advanced section where it is possible to control the number of iterations andrelative tolerance used by the plasticity algorithm.
• For the Drucker–Prager and Mohr–Coulomb models available in the Soil Plasticity,
Porous Plasticity, and Safety nodes, the intersection between the elliptic cap and thefailure surface has been corrected.
• The UI and some API names for the Plasticity node have been updated.
ENHANCEMENTS TO DAMAGE• Some user inputs in the Damage node can now be directly imported from theMaterials node.
• The default solver suggestions for Phase field damage have been improved.
• It is now possible to combine the Damage node with the Plasticity or Soil Plasticity
nodes.
• For the Scalar damage, the expression for the damaged stress variable is corrected
when used in combination with the mixed formulation.
TESTING OF SOIL MODELS

A new feature, Test Material, has been added to the Solid Mechanics interface. There,
it is possible to set up various numerical tests, including the Isotropic, Oedometer, andTriaxial tests for soil material models.

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85

Heat Transfer Module
New and Improved Functionality in Version 6.1
SPACECRAFT THERMAL ANALYSISThe new Orbital Thermal Loads physics interface provide ready-made features to model
radiative loads on spacecraft, in particular radiation from the Sun and the Earth forsatellites orbiting around Earth.
The user provides the spacecraft radiative properties, orbit and orientation, orbital
maneuvers, and planet properties. From this information, the physics interface
computes and generates graphics showing the direct solar radiation, albedo, and planet
infrared flux as well as the radiative heat transfer between the different spacecraft parts.
Combined with a heat transfer physics interface, it also accounts for heat conductionin the solid parts of spacecraft.
THERMAL CONNECTORS BETWEEN SHELLS AND DOMAINSThe Thermal Connection, Layered Shell, Edges; Thermal Connection, Layered Shell,
Surfaces; and Thermal Connection, Nonlayered Shell multiphysics couplings are designed

to define a continuity condition between the shared or facing surfaces between
temperature fields computed by a domain heat transfer interface and a shell heattransfer interface. The connector can be used for shells that are in contact through anedge, a boundary shared with the domain interface, or a boundary that is facing
another boundary from the domain interface. These multiphysics couplings greatly
simplifies the use of combined domain and shell interfaces in models.
SYMBOLS FOR RADIATION WITH THE OPACITY CONTROLLED OPTION

The symbols representing the emitted radiation direction are now also displayed when
the Opacity controlled option is used. The symbols are only available when the
Wavelength dependence of radiative properties option is set to Constant.
VERIFICATION TOOLS FOR SURFACE-TO-SURFACE RADIATION MODELSIn the Surface-to-Surface Radiation physics interface settings, in the View Factor
section, the Check consistency option has been added for the hemicube and ray
shooting methods. It is selected by default. This verification may have a noticeable
extra computational cost when the hemicube method is used. If so, a warning message

86 |CHAPTER 1: RELEASE NOTES

will inform you about it. In this case, once the model setup has been verified, theverification can be disabled.
SURFACE-TO-SURFACE RADIATION IMPROVEMENTS

The ray shooting method have been improved so that small surfaces are detected evenwhen a coarse resolution is used for the view factor evaluation. This is obtained byshooting additional rays, one for each group of boundaries detected in the geometry.
Combined with the resolution adaption, this improves the view factor accuracy with
an optimal number of rays. This may affect the results in case some small boundaries
were not detected previously due to a coarse resolution.
Also, for all view factor computation methods, expressions used to define variables andequations are now preprocessed to remove the previously used if statements testing theradiation direction. Now the expressions readability is facilitated and their evaluations
are much faster during the assembly step.
FLUENCE RATEIn the Surface-to-Surface Radiation interface it is now possible to add a Fluence Rate
Calculation node in order to select the domains where the fluence rate has to becomputed. The variable for fluence rate is <phys>.E0, where <phys> is the name of
the Surface-to-Surface Radiation physics interface, for example, rad.E0.
The fluence rate variable indicates the exposure to radiation if you were to place a small
object in a cavity.
CLIMATE DATA: ASHRAE 2021

ASHRAE Weather Data 2021 has been integrated into COMSOL Multiphysics®. C
ASHRAE 2021 contains additional locations; there are more than 8500 stations in the2021 edition. You can select any of them in the Ambient Properties node. The databaseprovides typical climate data for the temperature, humidity, precipitation, and solar
radiation.
ENHANCED THERMAL WALL FUNCTIONS FOR VISCOUS DISSIPATIONIn the Nonisothermal Flow coupling, when the Turbulence model type is set to RANS in
the single-phase flow interface, there is a new option, Thermal wall function, in the Heat
Transfer Turbulence section. It is set by default to Standard, which corresponds to thelegacy implementation and which is suitable for most of the configurations. The otheroption, High viscous dissipation at wall, accounts for viscous dissipation in the boundary
layer, which is not the case with the Standard option. This is needed for accurate resultsin case of fast internal flow, especially if the paths are narrow or the fluid is very viscous.

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87

EVAPORATION MASS SOURCE IN HYGROSCOPIC POROUS MEDIUM

The Moisture Flow multiphysics coupling has been updated so that the evaporation ratevariable computed by the Moisture Transport interface is accounted for in the massbalance computed by Brinkman Equations interface.
INFLOW AND OPEN BOUNDARY CONDITIONS FOR HYGROSCOPICPOROUS MEDIUMThe Open Boundary and Inflow boundary condition are now applicable to exterior
boundaries adjacent to domains where a Hygroscopic Porous Medium node is active.
USER-DEFINED PHASE TRANSITION FUNCTION FOR PHASE CHANGE
MATERIAL

A User-defined phase transition function is now available in the Phase Change Materialfeature. When it is selected, it is possible to define the phase transition function in thecorresponding user input.
IMPLEMENTATION OF SOME HEAT TRANSFER FEATURES ON THE
MATERIAL FRAME

The Solid, Building Material, Biological Tissue, Battery Layers, and Shape Memory Alloy
features are now defined on the material frame. This change has no effect unless thespatial and material frame differ. This is the case when moving mesh features are usedor when structural mechanics physics interfaces are combined with the heat transfer
physics interface.
SYNCHRONIZE MATERIAL PROPERTIES IN THE IDEAL GAS GROUP

Synchronization rules have been added for material properties for the Ideal gas group.
Thanks to this, if a property like Heat capacity at constant pressure is defined in the Basicgroup, the Ideal gas group definition is synchronized. Also, some rules are available todeduce a property from other properties available in the same group. For example, if
the Mean molar mass property is defined, then the Specific gas constant, Rs =Rconst /Mn is deduced from it, so you no longer need to define both.
SOLVER SUGGESTIONS FOR LUMPED THERMAL SYSTEMS

Solver suggestions for the Lumped Thermal System physics interface have been
improved to be automatically merged with the solver suggestions from heat transfer
interfaces when Lumped Thermal Connector features are active. This is particularly
important for large models using an iterative solver. In this case, hybrid
preconditioners are defined.

88 |CHAPTER 1: RELEASE NOTESNew Applications in Version 6.1
ORBIT CALCULATIONThis model is an introduction to defining and verifying a satellite orbit and computing
the solar, albedo, and Earth infrared (IR) thermal loads. A 1U CubeSat is in a circularorbit at 400 km altitude, with an inclination of 50° and a longitude of ascending nodeof 0°. The satellite is rotating slowly about its nadir-pointing axis. One orbital period
is analyzed, during the winter solstice. The total irradiation and the radiative loads
from all environmental sources are computed. This type of analysis is usually
performed prior to computing the temperature evolution within the structure of thesatellite.
ORBIT THERMAL LOADS

A satellite in orbit experiences solar, albedo, and planetary IR loads, where albedo andplanetary IR can vary with latitude and longitude. This model demonstrates how todefine Earth properties that are spatially varying. It shows how to read spreadsheet andimage data and how to define and use different functions. The total irradiation and flux
onto the satellite are evaluated over several orbits and the albedo flux is plotted overthe surface of the Earth.
SPACECRAFT THERMAL ANALYSISThis model shows the workflow for computing the satellite temperature on multiple
orbit periods. The direct solar, albedo, and Earth infrared thermal loads areprecomputed in an Orbit Thermal Loads study and reused on multiple orbit periods inan Orbital Temperature study.

Updated Applications in Version 6.1
The tutorials have been updated to take advantage of the latest geometry, mesh, andsolver features in order to have simplified step-by-step instructions for the model
construction. In addition to these updates, some tutorials have been updated
regarding physical modeling:• The Disk Stack Heat Sink model is now using the new
Thermal Connection, Layered Shell, Edges multiphysics coupling.
• The Continuous Casting ALE and Friction Stir Welding models are now using
the new Solid with Translational Motion feature.

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• The Brake Disk model now uses Moving Mesh features instead of Translational Motion
to improve the computational performance.
• The Thermal Bridges in Building Construction — 2D Composite Structure,
Thermal Bridges in Building Construction — 2D Square Column, Thermal
Bridges in Building Construction — 3D Iron Bar, and Thermal Bridges in
Building Construction — 3D Two Floors models have been updated to match the2017 version of the ISO norm 10211.

Backward Compatibility with Version 6.0• In version COMSOL Multiphysics® 6.0, when the From material option was
selected in Shape Memory Alloy feature for the heat capacity at constant pressure, Cp,
the property was taken from the material Basic group. In version 6.1, the material
properties CpA and CpM are taken from the groups Austenite Phase and Martensite
Phase, respectively. Identity rules enable to ensure backward compatibility in mostcases. However, if different values were set for Cp and CpA or CpM, the results may
differ between versions 6.0 and 6.1.
• In the Symmetry for Surface-to-Surface Radiation feature of the Surface-to-Surface
Radiation interface, the check box Apply symmetry to external radiation sources isselected by default in version 6.1. API script need to be updated by clearing thischeck box to get the same results as in version 6.0 when there are both a Symmetryfor Surface-to-Surface Radiation and an External Radiation Source feature in the model.
• It is now no longer possible to set an Inflow, Outflow or an Open Boundary condition
on boundaries of Shape Memory Alloy or Building Material domains.
• In the Surface-to-Surface Radiation interface features, the diffuse irradiance variables(Idiff, Idiffu_band, Idiffd_band, Idiff_band) are set to 0 when the Include
diffuse irradiance check box is not selected.
• In the settings of the Surface-to-Surface Radiation interface, the Mesh element selfirradiation check box does not exist in version 6.1. Self-irradiation is always taken
into account when High order mesh elements is selected.
• In the settings of the Surface-to-Surface Radiation interface, the High order meshelements check box is available for the following combinations in version 6.1: theray shooting method in 3D, 2D axisymmetric and 2D, and the hemicube method
in 2D axisymmetric and 2D. In case the model saved in version 6.0 had the Highorder mesh elements check box selected, the behavior in version 6.1 is the same as
when this check box was cleared. View factor results should be checked forconsistency.

90 |CHAPTER 1: RELEASE NOTES• The contribution of the shell curvature on gradient definition to account for thesurface area change has been corrected for cases where the shell normal is pointing
towards the center of curvature.
• The speed of sound variable definition has been corrected in the Fluid and Moist Air
features and subfeatures.
• For turbulent nonisothermal flow, the constraints added to guarantee the continuityof the temperature between multiple wall boundaries has been revised to be much
faster to treat in case of very large number of boundaries, and to improve thereadability of the Equation view.
• Refactored Boundary Heat Source feature to give the control if the continuity isprescribed or not, and to control where the source is added: source, destination orboth.
• Updated the heat source contribution in Heat Transfer with Radiative Beam in
Absorbing Media coupling in case of temperature variation across the boundary to
account for the side of the boundary that absorbs the radiation.
• In the Building Material feature, the material properties are now interpreted in thematerial frame. This affects models where a Building Material feature is on a domain
where the spatial frame is controlled by an interface, such as a Moving Mesh. The Mass
Properties node now handles Building Material features and can be used to computethe total mass.

Backward Compatibility with Version 5.6• In the Prescribed Radiosity feature in the Surface-to-Surface Radiation interface, if thegraybody model is selected to define the radiative intensity, the emissivity istemperature dependent, and the temperature model input is automatically definedfrom a multiphysics coupling in an API script, then you must update the script todefine Text. In other cases, Text is set to the value that was set to the model input
in version 5.6 or earlier so that the model behavior is unchanged.
• In Heat Transfer interfaces, in the Deposited Beam Power boundary condition, forUser defined beam profiles, the beam intensity is now defined from its value in the
beam cross section, which corresponds to the deposited beam power divided by thecosine of the incidence angle. Nevertheless, for User defined beam profiles, themodels and API scripts created in version 5.6 or earlier behave identically in version
6.0.
• In the Opaque Surface feature of the Surface-to-Surface Radiation interface, thecoordinate system choice is restricted to the boundary system. When opening a

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model created in version 5.6 or earlier with another coordinate system selected, this
input should be checked for consistency.
• In the Surface-to-Surface Radiation interface, when the Expression or Tolerance
settings had been modified in the View Factor Update section of a model created inversion 5.6 or earlier, these settings are reported in the new View Factor section.
• A modification of the numerical results within the solver tolerance range may beobserved when computing surface-to-surface radiation models created in version
5.6 or earlier, due to the introduction in the Surface-to-Surface interface of theJacobian contribution option set by default to Only local contributions to radiosity.
When opening a model created in version 5.6 or earlier, a warning is displayed under
the Surface-to-Surface Radiation interface. Note that the accuracy level remains thesame because the convergence criteria and the solver tolerance are unchanged.
• The Local Thermal Nonequilibrium predefined multiphysics interface and the Local
Thermal Nonequilibrium multiphysics coupling are now obsolete. When opening amodel created in version 5.6 or earlier, this feature is not migrated. It should be
manually replaced by the Porous Medium feature with the Porous medium type set toLocal thermal nonequilibrium. Support for features marked as obsolete is not ensured
in future versions; thus it is strongly recommended to transfer this feature to the newfeature.
• In the Moisture Transport interface, the Hygroscopic Porous Medium feature notsupporting the Porous Material functionality is now obsolete. When opening a model
created in version 5.6 or earlier, this feature is not migrated. It should be manuallyreplaced by the new Hygroscopic Porous Medium feature. Support for features marked
as obsolete is not ensured in future versions; thus it is strongly recommended totransfer this feature to the new feature.

Backward Compatibility with Version 5.5• The Heat and Moisture multiphysics coupling feature is no longer applicable todomains where the Fluid (Heat Transfer interface) feature is active. Models built inversion 5.5 and before, where the Heat and Moisture multiphysics feature and the
Fluid feature with the Moist air option have been used, are updated when opened inversion 5.6. The Fluid feature is then replaced by the Moist air feature so themultiphysics coupling is still active. In the unexpected case where the Heat andMoisture multiphysics feature and the Fluid feature with an option other than Moist
air were combined, the multiphysics coupling is no longer active in version 5.6,
which is likely to modify the model solution.

92 |CHAPTER 1: RELEASE NOTES• In the Surface-to-Surface Radiation interface, the Opaque Surface andSemitransparent Surface features not supporting directional dependence of surface
properties are now obsolete. When opening a model created in version 5.5 or earlier
in the user interface, these features are not migrated. They should be manuallyreplaced by the new Opaque Surface and Semitransparent Surface features to accountfor directional dependence of surface properties. Support for features marked as
obsolete is not ensured in future versions; thus it is strongly recommended totransfer all these features to the new features.
• In the Heat Transfer interfaces, the Porous Medium feature not supporting the new
Porous Material functionality is now obsolete. When opening a model created inversion 5.5 or earlier in the user interface, this feature is not migrated. It should be
manually replaced by the new Porous Medium feature (which comes with Porous
Matrix and Fluid subfeatures) to allow an updated definition of the material
properties of the porous medium. Support for features marked as obsolete is not
ensured in future versions; thus it is strongly recommended to transfer this feature
to the new feature.
• The Temperature feature is no longer applicable on boundaries adjacent to a domain
where the Isothermal Domain feature is active. When opening a model built inversion 5.5 and before, where the Temperature feature is applied in this way, thenode is present but the feature is not active, which is likely to modify the model
solution.
• The Open Boundary feature is no longer applicable on boundaries adjacent to a
nonfluid domain. When opening a model built in version 5.5 and before, where theOpen Boundary feature is applied in this way, the node is present but the feature is
not active, which is likely to modify the model solution.
• The Surface-to-surface radiation interface is no longer applicable on boundaries thatbelong to infinite element domains, perfectly matched layer domains or absorbing
domains since the view factor computation does not account for the corresponding
coordinate system change.

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Liquid & Gas Properties Module
Improved Functionality in Version 6.1• Evaluation of thermodynamic properties is now faster. Models where a significant
part of the solution time is spent evaluating functions from the Thermodynamics
functionality can now be solved in 30% less time.
• The filter search field, used when adding species to a thermodynamic system, hasbeen improved. Filtered species can now be entered one at a time, from the top,
using the Enter key. Also, it is no longer necessary to update the filter each time a
species is added to the Selected species list.

New Model in Version 6.1
CO2 STORAGE IN A GEOLOGIC FORMATIONThis example simulates the underground storage of CO2 in a part of the Johansen
formation off the coast of Norway. The CO2 is injected using an injection well at a rateof 15 kg/s over a period of 25 years, after which the well is closed. The model is used
to compute the spreading of CO2 over the simulation domain during the injection
phase and during the 25 years directly following the shut down of the injection well.
The pressure- and temperature-dependent density and viscosity of supercritical CO2
are computed using the Peng–Robinson equation of state and the Brokaw viscosity
model with high-pressure correction.

94 |CHAPTER 1: RELEASE NOTESM E M S M o dule
New Functionality in Version 6.1
NEW MULTIPHYSICS INTERFACE: PYROELECTRICITY

The new Pyroelectricity multiphysics interface combines a Heat Transfer in Solids
interface and an Electrostatics interface, coupled by the new Pyroelectricity
multiphysics coupling. Both the direct pyroelectric effect and the inverse electrocaloric
effect can be modeled.
NEW MULTIPHYSICS INTERFACE: PIEZOELECTRICITY ANDPYROELECTRICITY

The new Piezoelectricity and Pyroelectricity multiphysics interface combines a Heat
Transfer in Solids interface, an Electrostatics interface, and a Solid Mechanics interface.
Three multiphysics couplings are also used in these multiphysics interfaces:
Pyroelectricity, Thermal Expansion, and Piezoelectric Effect. This provides a full coupling
between pyroelectric effects, piezoelectricity, and thermal expansion of the material.
SOLID MECHANICS INTERFACE IN 1D AND 1D AXISYMMETRY

For details, see Solid Mechanics interface in 1D and 1D axisymmetry in the release
notes for the Structural Mechanics Module.
TESTING OF MATERIAL MODELSFor details, see Testing of Material Models in the release notes for the Structural
Mechanics Module.
MATERIALS ON BOUNDARIES OF SOLIDS

For details, see Materials on Boundaries of Solids in the release notes for the Structural
Mechanics Module.
MULTIPHYSICS INTERFACES FOR THIN-FILM DAMPING

For details, see Multiphysics Interfaces for Thin-Film Damping in the release notes for
the Structural Mechanics Module.
MAGNETOSTRICTION INTERFACE CHANGESFor details, see Magnetostriction Interface Changes in the release notes for the
Structural Mechanics Module.

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DEAD LOADS IN LINEARIZED BUCKLING ANALYSIS

For details, see Dead Loads in Linearized Buckling Analysis in the release notes for the
Structural Mechanics Module.
CONTINUITY USING NITSCHE’S METHOD

For details, see Continuity Using Nitsche’s Method in the release notes for the
Structural Mechanics Module.
COMPONENT MODE SYNTHESIS IMPROVEMENTS

For details, see Component Mode Synthesis Improvements in the release notes for the
Structural Mechanics Module.
NEW SEARCH METHOD FOR CONTACT ANALYSIS

For details, see New Search Method for Contact Analysis in the release notes for the
Structural Mechanics Module.
CONTACT USING NITSCHE’S METHOD

For details, see Contact Using Nitsche’s Method in the release notes for the Structural
Mechanics Module.
NEW FORMULATION FOR CONTACT EQUATIONS

For details, see New Formulation For Contact Equations in the release notes for the
Structural Mechanics Module.
IMPROVED SUPPORT FOR SELF-CONTACT

For details, see Improved Support for Self-Contact in the release notes for the
Structural Mechanics Module.
POSSIBLE TO TRIGGER A CUTBACK IN THE SOLVER FOR ALL CONTACTMETHODSFor details, see Possible to Trigger a Cutback in the Solver for All Contact Methods inthe release notes for the Structural Mechanics Module.
BASE EXCITATION

For details, see Base Excitation in the release notes for the Structural Mechanics
Module.

96 |CHAPTER 1: RELEASE NOTESGRAVITY AND LINEARLY ACCELERATED FRAME

For details, see Gravity and Linearly Accelerated Frame in the release notes for the
Structural Mechanics Module.
LOADS GIVEN AS RESULTANT

For details, see Loads Given as Resultant in the release notes for the Structural
Mechanics Module.
RESULTS IN LOCAL DIRECTIONS

For details, see Results in Local Directions in the release notes for the Structural
Mechanics Module.
NEW INPUT OPTIONS FOR NONISOTROPIC ELASTIC MATERIALSFor details, see New Input Options for Nonisotropic Elastic Materials in the release
notes for the Structural Mechanics Module.
MULTIPLICATIVE FORMULATION FOR PIEZOELECTRICITY

For details, see Multiplicative Formulation for Piezoelectricity in the release notes for
the Structural Mechanics Module.
CELL PERIODICITY CAN CREATE MATERIAL DATA ON COMPLIANCE FORM

For details, see Cell Periodicity can Create Material Data on Compliance Form in therelease notes for the Structural Mechanics Module.
EXTENDED BUILT-IN MATERIAL

For details, see Extended Built-In Material in the release notes for the Structural
Mechanics Module.
LIBRARY OF PARTS FOR HOMOGENIZATION OF MICROSTRUCTURES

For details, see Library of Parts for Homogenization of Microstructures in the release
notes for the Structural Mechanics Module.
RELEASED DEGREES OF FREEDOM IN RIGID CONNECTOR

For details, see Released Degrees of Freedom in Rigid Connector in the release notes
for the Structural Mechanics Module.
SINGULARITY SUPPRESSION FOR TWO-POINT RIGID CONNECTOR

For details, see Singularity Suppression for Two-Point Rigid Connector in the release
notes for the Structural Mechanics Module.

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NEW FORMULATION OF RIGID MOTION SUPPRESSION

For details, see New Formulation of Rigid Motion Suppression in the release notes for
the Structural Mechanics Module.
IMPROVED PERFORMANCE FOR RANDOM VIBRATION EVALUATION

For details, see Improved Performance for Random Vibration Evaluation in the release
notes for the Structural Mechanics Module.
RIGID DOMAIN RENAMED TO RIGID MATERIAL

For details, see Rigid Domain Renamed to Rigid Material in the release notes for the
Structural Mechanics Module.
REDUCED NUMBER OF DEFAULT PLOTS

For details, see Reduced Number of Default Plots in the release notes for the Structural
Mechanics Module.
PREVIEW PLOT FOR RAYLEIGH DAMPING

For details, see Preview Plot for Rayleigh Damping in the release notes for the
Structural Mechanics Module.
NEW OPTION FOR GENERATION OF MATERIAL DATA IN CELLPERIODICITY

For details, see New Option for Generation of Material Data in Cell Periodicity in therelease notes for the Structural Mechanics Module.
GROUPING OF ODE VARIABLES IN SOLVER

For details, see Grouping of ODE Variables in Solver in the release notes for the
Structural Mechanics Module.
RESTRUCTURED REDUCED-ORDER MODEL STUDIESFor details, see Restructured Reduced-Order Model Studies in the release notes for the
Structural Mechanics Module.
LIMITATIONS OF SELECTIONS ON AXIS OF ROTATION

For details, see Limitations of Selections on Axis of Rotation in the release notes for
the Structural Mechanics Module.

98 |CHAPTER 1: RELEASE NOTESREMOVED SECTION IN PHYSICS INTERFACE SETTINGS

For details, see Removed Section in Physics Interface Settings in the release notes for
the Structural Mechanics Module.

New Models in Version 6.1
CAPACITIVE MICROMACHINED ULTRASONIC TRANSDUCER

This model demonstrates the operation of a capacitive micromachined ultrasonictransducer (CMUT) for converting ultrasound into electrical signal in high-resolution
imaging applications. The transducer is connected to an external circuit and a
Harmonic Perturbation boundary load represents the ultrasonic energy. The model
also analyzes force-displacement characteristics of the transducer.
ELECTROSTATIC CHUCKThis model demonstrates the operation of an electrostatic chuck used to secure a wafer
on a temperature-controlled platform during wafer processing. The model computes
the pressure-dependent cooling of the wafer using Electromechanical Forces, Fluid–
Structure Interaction, Nonisothermal Flow, and Thermal Expansion couplings.
NORMAL MODES OF A BIASED RESONATOR 3D GEOMETRY FROM A GDSFILE

This tutorial demonstrates how to build complex 3D geometry more efficiently using
the layer-by-layer method that resembles actual MEMS fabrication. This model creates
the biased resonator by importing layouts from a GDS file and by using operations
available in the CAD Import Module and the Design Module. The model solves forthe eigenmodes of the structure.
PRESTRESSED MICROMIRROR VIBRATIONS: THERMOVISCOUSTHERMOELASTICITY COUPLING

This model analyzes the operation of a prestressed micromirror in air. The model
includes the effects of thermal losses and thermoviscous damping on the vibration
response. This model demonstrates the use of the Thermoviscous Acoustics–
Thermoelasticity Boundary multiphysics coupling.
PYROELECTRIC DETECTORThis model demonstrates the operation of a lithium niobate (LiNbO3) pyroelectricdetector used for measuring laser energy. The detector is connected to an external
circuit and a pulsed heat flux represents the laser energy. It computes the temperature

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evolution in the material and the pyroelectric current and is set up using the
Piezoelectricity and Pyroelectricity interface.

100 |CHAPTER 1: RELEASE NOTESM e ta l P r o c e s s i n g Mod u l e
New Functionality in Version 6.1
ALPHA-BETA PHASE TRANSFORMATION INTERFACEA new physics interface, Alpha-Beta Phase Transformation, has been added to simulate
phase transformations in - titanium alloys.
NEW PHASE TRANSFORMATION MODEL

A Hyperbolic rate phase transformation model has been added to the phasetransformation interfaces.
1D AND 1D AXISYMMETRIC FORMULATIONS

The physics interfaces and multiphysics couplings are now available also for 1D and 1D
axisymmetric components.
TRANSFORMATION TEMPERATURE SMOOTHING

A Transformation temperature smoothing option is available in conjunction with theDefine temperature limits option. This can be used to make activation and deactivationof phase transformations less abrupt.
PHASE-DEPENDENT ELECTROMAGNETIC PROPERTIESElectromagnetic material properties can now be defined per phase, and corresponding
compound material properties can be computed. This is useful in the context of
induction heating.
PARAMETERIZED TTT DIAGRAMS

The phase transformation model formulations Parameterized TTT diagram andParameterized TTT diagram, fixed exponent have been added. They are used tocharacterize diffusive phase transformations using simplified, parameterized
descriptions of time-temperature-transformation (TTT) diagram curves.

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MISCELLANEOUS• The effect of the Initial phase fraction can optionally be included in the rate
expression for the Johnson-Mehl-Avrami-Kolmogorov (JMAK) phase transformation
model.
• When Compute transformation times is used, a transformation diagram is
automatically generated. This can be used to compute continuous coolingtransformation (CCT) and TTT diagrams.

New Models in Version 6.1
WELDING OF A TITANIUM PLATE

This model simulates arc welding of a titanium plate made from an alpha-beta titanium
alloy. During a weld pass, the material experiences a thermal transient, including bothheating and cooling. Phase transformations are modeled, and the evolution of thephase composition over time is computed.

102 |CHAPTER 1: RELEASE NOTESMicrofluidics Module
New Functionality in Version 6.1
MULTIPHASE MATERIALS FOR MULTIPHASE FLOW COUPLINGSThe Two-Phase Flow, Level Set, Two-Phase Flow, Phase Field, and Three-Phase Flow, Phase
Field multiphysics couplings have a new option to obtain the effective material

properties from a Multiphase Material with built-in mixing rules. This is especiallyeffective when coupling these multiphysics interfaces with other physics, such as heattransfer or electrostatics, since the multiphase material will use appropriate mixing
rules for nonfluid material properties. In older versions, this would require you writinguser-defined expressions based on the volume fraction of each fluid phase to computethe effective material properties used in each physics interface.
INELASTIC NON-NEWTONIAN MATERIAL PROPERTY GROUPS

Dedicated material property groups have been added for all available inelastic nonNewtonian models. The material property group contains all necessary material
parameters and the apparent viscosity expression. It picks up the shear rate from thefluid flow interface to define the dynamic viscosity in the Basic (def) material model bymeans of a synchronization rule. Thus, an inelastic non-Newtonian model can beselected directly by adding the corresponding Material Properties group as a subnodeto a material node.
IMPROVEMENTS TO THE LEVEL SET INTERFACEIn the Level Set interface, a new Porous Medium feature now supports the functionality
to update the definition of the porosity in the Materials node. The new Level Set in
Porous Media interface includes this node by default.

Updated Applications in Version 6.1
The tutorials have been updated to take advantage of the latest geometry, mesh, andsolver features in order to provide simplified step-by-step instructions for the model
construction. Applications using Two-Phase Flow, Level Set, Two-Phase Flow, Phase
Field, or Three-Phase Flow, Phase Field interfaces now include a Multiphase Material tocompute the effective material properties from volume fractions and the material
properties of each phase.

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Backward Compatibility with Version 6.0• An error in the expression for the mean free path when using theAlternative (Sharipov) option for the Mean free path definition under User defined in
the External Slip Wall and Interior Slip Wall features has been corrected. This mightlead to slight differences in the results. In addition, the default values for theStandard option for the Mean free path definition setting have been modified tocorrespond to those of the Alternative (Sharipov) option.
• Non-Newtonian inelastic material models that were added in older versions will not
be able to define the dynamic viscosity in the Basic (def) material model.

Backward Compatibility with Version 5.5 and Earlier
TWO-PHASE FLOWIn the Level Set and Phase Field interfaces, the Initial Interface feature is now obsolete.
It does not need to be replaced because the phase interfaces are automatically detectedfrom the selection of the Initial Values features, and the initial distribution of the levelset or phase field function is solved for in the Phase Initialization study step.

104 |CHAPTER 1: RELEASE NOTESM o le c ula r Flow Mod u l e
New Functionality in Version 6.1
SYMMETRY

The new global Symmetry node extends the capability of the Plane Symmetry node. In
2D, you can specify either a single symmetry plane or two orthogonal planes. In 3D,
you can now specify either one, two, or three symmetry planes as long as all of theplanes are mutually orthogonal.
With this node, you can also apply sector symmetry to your models. This can be donein two different ways: by selecting the boundaries in the start plane and end plane of asingle sector (or unit cell) of the symmetric geometry or by selecting the start plane
and a reflection plane (where the model geometry is assumed to be one half of a single
sector).

Updated Applications in Version 6.1
DIFFERENTIAL PUMPING

This model has been updated to use the new Symmetry feature.
MOLECULAR FLOW THROUGH AN RF COUPLER

This model has been updated to use the new Symmetry feature.

Backward Compatibility with Version 6.0 and Earlier
PLANE SYMMETRY

The Plane Symmetry node is still available in version 6.1. Any models created with aprevious version using the Plane Symmetry nodes will generate identical results when
computed in version 6.1. However, a warning message will be displayed stating, “Thisfeature is obsolete and will be removed in future versions. Consider using the new
global Symmetry feature instead. Do not attempt to use both of these features
together.” Consequently, replacing the old Plane Symmetry with the new Symmetry
feature is recommended.

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Multibody Dynamics Module
New Functionality in Version 6.1
PHYSICS INTERFACE FOR WIRESFor details, see Physics Interface for Wires in the release notes for the Structural
Mechanics Module.
CONTINUITY USING NITSCHE’S METHOD

For details, see Continuity Using Nitsche’s Method in the release notes for the
Structural Mechanics Module.
COMPONENT MODE SYNTHESIS IMPROVEMENTS

For details, see Component Mode Synthesis Improvements in the release notes for the
Structural Mechanics Module.
NEW SEARCH METHOD FOR CONTACT ANALYSIS

For details, see New Search Method for Contact Analysis in the release notes for the
Structural Mechanics Module.
CONTACT USING NITSCHE’S METHOD

For details, see Contact Using Nitsche’s Method in the release notes for the Structural
Mechanics Module.
NEW FORMULATION FOR CONTACT EQUATIONS

For details, see New Formulation For Contact Equations in the release notes for the
Structural Mechanics Module.
IMPROVED SUPPORT FOR SELF-CONTACT

For details, see Improved Support for Self-Contact in the release notes for the
Structural Mechanics Module.
POSSIBLE TO TRIGGER A CUTBACK IN THE SOLVER FOR ALL CONTACTMETHODSFor details, see Possible to Trigger a Cutback in the Solver for All Contact Methods inthe release notes for the Structural Mechanics Module.

106 |CHAPTER 1: RELEASE NOTESBASE EXCITATION

For details, see Base Excitation in the release notes for the Structural Mechanics
Module.
GRAVITY AND LINEARLY ACCELERATED FRAME

For details, see Gravity and Linearly Accelerated Frame in the release notes for the
Structural Mechanics Module.
LOADS GIVEN AS RESULTANT

For details, see Loads Given as Resultant in the release notes for the Structural
Mechanics Module.
RESULTS IN LOCAL DIRECTIONS

For details, see Results in Local Directions in the release notes for the Structural
Mechanics Module.
NEW INPUT OPTIONS FOR NONISOTROPIC ELASTIC MATERIALSFor details, see New Input Options for Nonisotropic Elastic Materials in the release
notes for the Structural Mechanics Module.
RELEASED DEGREES OF FREEDOM IN RIGID CONNECTOR

For details, see Released Degrees of Freedom in Rigid Connector in the release notes
for the Structural Mechanics Module.
SINGULARITY SUPPRESSION FOR TWO-POINT RIGID CONNECTOR

For details, see Singularity Suppression for Two-Point Rigid Connector in the release
notes for the Structural Mechanics Module.
NEW FORMULATION OF RIGID MOTION SUPPRESSION

For details, see New Formulation of Rigid Motion Suppression in the release notes for
the Structural Mechanics Module.
RIGID DOMAIN RENAMED TO RIGID MATERIAL

For details, see Rigid Domain Renamed to Rigid Material in the release notes for the
Structural Mechanics Module.
REDUCED NUMBER OF DEFAULT PLOTS

For details, see Reduced Number of Default Plots in the release notes for the Structural
Mechanics Module.

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107

PREVIEW PLOT FOR RAYLEIGH DAMPING

For details, see Preview Plot for Rayleigh Damping in the release notes for the
Structural Mechanics Module.
GROUPING OF ODE VARIABLES IN SOLVER

For details, see Grouping of ODE Variables in Solver in the release notes for the
Structural Mechanics Module.
REMOVED SECTION IN PHYSICS INTERFACE SETTINGS

For details, see Removed Section in Physics Interface Settings in the release notes for
the Structural Mechanics Module.

108 |CHAPTER 1: RELEASE NOTES

Nonlinear Structural Materials
ModuleNew Functionality in Version 6.1
VISCOPLASTICITY IMPROVEMENTS

The functionality in the Viscoplasticity node has been subject to major changes:• A new framework to handle large viscoplastic strains has been implemented. It isbased on the multiplicative decomposition of deformation gradients.
• The new formulation for large strains makes it possible to add Creep andViscoplasticity nodes under the Hyperelastic Material node in the Solid Mechanics
interface.
• Two new viscoplastic models have been introduced: the Bingham model and the
Peric model. It is also now possible to have a User defined viscoplastic model.
• A new general framework provides significant improvements in computational
speed and memory usage. For larger models, a speedup by a factor of 10 or more
can be expected.
• The Chaboche and Perzyna models have been updated. The main change is withrespect to the time integration. You can now select the type of scheme that is used.
In the Time Stepping section, you can set Method to Automatic, Backward Euler, orDomain ODEs. The latter method provides backward compatibility with versions
prior to 6.0 and is usually significantly slower for large models. This section is notpresent in the Layered Shell interface or in the layered material models in the
Membrane and Shell interfaces.
As an effect of these changes, there are some potential backward compatibility
issues:- API code that references the old field names in order to modify solver settings
will fail.
- Manual variable scaling of the viscoplastic degrees of freedom will be lost, evenwhen Domain ODEs is selected.
• The UI and some API names for the Viscoplasticity node have been updated.

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HYPERELASTICITY IMPROVEMENTS

The functionality in the Hyperelastic Material node has been subject to major changes:• A new framework to handle the compressibility for all hyperelastic materials has
been implemented. Five new volumetric strain energy variables are now available. As
a result, all hyperelastic material models now have a compressible option.
• It is now possible to add Phase Field damage to Hyperelastic Material nodes in the
Solid Mechanics interface.
• The stress variables are restructured in the Hyperelastic Material node and its
subnodes in the Solid Mechanics, Shell, Layered Shell, and Membrane interfaces. As
a result, large strain viscoelasticity now uses the elastic isochoric stress as the source
for the relaxation equations.
• The incompressible or nearly incompressible hyperelastic materials now generatecorrect postprocessing results when inelastic stresses are added.
• The new formulation for large strains makes it possible to add Creep andViscoplasticity nodes under the Hyperelastic Material node in the Solid Mechanics
interface.
• For incompressible hyperelastic materials, the volumetric damping is set to zero for
isotropic loss factor damping and viscous damping.
• The User defined hyperelastic strain energy density can be expressed as a function of
the elastic deformation gradient.
• For the user-defined hyperelastic material, there is a new Advanced section in which
variables for the equivalent stiffness needed for contact problems can be defined.
ENHANCEMENTS TO DAMAGE• Some user inputs in the Damage node can now be directly imported from theMaterials node.
• The Phase field damage is added to the Hyperelastic Material node in the Solid
Mechanics interface.
• The default solver suggestions for Phase field damage have been improved.
• It is now possible to combine the Damage node with the Plasticity, Soil Plasticity, andViscoplasticity nodes.
• For Scalar damage, the expression for the damaged stress variable is corrected whenused in combination with the mixed formulation.

110 |CHAPTER 1: RELEASE NOTESENHANCEMENTS TO WRINKLING• It is now possible to model wrinkling of rubber or biological tissue by adding the
Wrinkling node under the Hyperelastic Material node in the Membrane interface.
• The Plasticity, Viscoplasticity, Creep, and Inelastic Strain Rate nodes are now
overridden by the Wrinkling node in the Membrane interface.
ENHANCEMENTS TO PLASTICITY• The Plasticity, Porous Plasticity, and Shape Memory Alloy nodes now have an Advanced
section where it is possible to control the number of iterations and relative tolerance
used by the plasticity algorithm.
• The UI and some API names for the Plasticity node have been updated.
ADDITIONAL FUNCTIONALITY FOR THIN LAYER

In the Solid Mechanics interface, the new Thin Layer node can add Hyperelastic andNonlinear Elastic material models. Other inelastic effects can also be added to material
models under the Thin Layer node by adding, for example, Damage, Creep, or Plasticity
subnodes.
ADIABATIC HEATING

A new framework to handle adiabatic heating in solids, shells, and membranes is
implemented. Adiabatic heating is important when rapid deformations dissipate
energy, which in turn increases the temperature in the object. To incorporate thiseffect, you can add an Adiabatic Heating subnode to the Solid Mechanics, Layered Shell,
Shell, or Membrane interfaces.
NEW BUILT-IN MATERIAL

A new material, Rubber, has been added to the Built-in folder in the Material Library.
It contains material data for a generic rubber material that can be used in several of thematerial models under the Hyperelastic Material node.
Also, the existing Structural Steel material has been augmented with many new
nonlinear material properties to be used with, for example, plasticity or creep.

New Models in Version 6.1
WRINKLING OF A CYLINDRICAL MEMBRANE WITH VARYING THICKNESSIn this example, wrinkling is studied in a cylindrical membrane of nonuniform
thickness under axial and pressure loading. The membrane is modeled as an

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incompressible Mooney–Rivlin material. During axial stretching, certain portions of
the membrane undergo wrinkling; however, the wrinkling disappears when theinternal pressure is increased.
INFLATION OF A SQUARE HYPERELASTIC AIRBAG

In this example, a square airbag made of a hyperelastic compressible neo-Hookean
material is inflated using pressurized air. Compressive stresses trigger wrinkling in someregions of the thin airbag.
The wrinkling behavior is modeled using tension field theory, which provides a correct
description of the stress distribution and the wrinkling pattern in the inflated
membrane.
CONTACT ANALYSIS OF A RUBBER BOOT SEAL

In this example, the deformation of a rubber boot seal connected to a rigid pipe isstudied. As the pipe rotates and the seal deforms, the flanges of the seal self-intersect,
and the seal also comes into contact with the pipe.
INTERFACE MODELS WITH A THIN LAYER FEATURE

This model demonstrates alternative implementations used for describing a thin layer
as well as the impact of the choice on the continuity of the displacement and stressfields. The model shows how a perfect interface can be obtained by asymptoticallychanging the material parameters.
SUBMODELING WITH PLASTICITYThis tutorial model demonstrates how to incorporate a localized nonlinearity into asubmodel.
In this example, an initial elastic analysis reveals that a small region of a structure has
stresses above the yield limit. To improve the results, an elastoplastic material model isadded to a submodel.
The global model is analyzed using linear elasticity in this case, but this is not anecessary assumption.

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Optimization Module
New Functionality in Version 6.1
GRADIENT-BASED OPTIMIZATION FOR EIGENVALUE PROBLEMS

Gradient-based optimization is now supported for eigenvalue problems when theobjective (or constraints) depends explicitly on the eigenvalues. Related to this, thePolynomial Boundary feature has been extended to 3D, and a Polynomial Shell feature
has been added. This combination of new functionality enables gradient-based shape
optimization of shells in terms of the lowest eigenfrequency.
MILLING CONSTRAINTS FOR TOPOLOGY OPTIMIZATION

For topology optimization, the Density Model feature has been extended with support
for milling constraints. The resulting topologies can often be used as inspiration forgeometries subject to casting constraints.
CONTINUITY FOR FREE SHAPE AND POLYNOMIAL BOUNDARY FEATURESThe Free Shape Boundary, Free Shape Shell, 2D Polynomial Boundary, and Polynomial Shell
features have been extended with settings for continuity so that it is easier to preserve
slope continuity during shape optimization.
The Transformation feature has been extended with support for free rotation androtation around an axis confined to a plane.
The Fixed Boundary feature used to be a hidden default boundary condition in shape
optimization, but it is now visible in the user interface.
ADDITIONAL NEW FUNCTIONALITYThe Control Function feature has been extended to support piecewise polynomials. The
slope is continuous between the polynomials. This is also the case for periodic
functions.
The default solver suggestion for optimization has been changed to use an iterativesolver, which reduces memory consumption for large 3D shape optimization
problems.

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New and Updated Models in Version 6.1
MAXIMIZING THE EIGENFREQUENCY OF A SHELL

This model demonstrates how to use the Polynomial Shell feature to increase the lowest
eigenfrequency of a shell by deforming its shape.
BRACKET — STRESS OPTIMIZATION WITH FATIGUE EVALUATIONThis example demonstrates shape optimization together with a structural fatigue
evaluation and minimizes the approximate maximum stress of a bracket. The mass andstiffness are constrained with respect to the initial values. The fatigue life is improved
after optimization as compared to the initial geometry.
TOPOLOGY OPTIMIZATION OF A STEP THRUST BEARING

Topology optimization is used to design a step thrust bearing capable of supporting alarge load. Designs with different numbers of grooves can be identified by modifying
the initial design. The result is verified with a body-fitted mesh.
SHAPE OPTIMIZATION OF A STEP THRUST BEARING

Shape optimization is used to design a step thrust bearing capable of supporting a large
load. Control Function features are used to move the steps in the azimuthal direction.
TOPOLOGY OPTIMIZATION OF A BEAM WITH MILLING CONSTRAINTS

The mass of an aluminum beam is minimized through topology optimization subject
to a displacement constraint and a distributed load. This previously available model has
been modified to demonstrate the use of the new milling constraints with milling fromthe x- and y-axes.
EXPORTING AND IMPORTING A TOPOLOGY-OPTIMIZED HOOK

In this topology optimization of a hook, the simulation finds the optimal material
distribution when the structural part is subjected to two load cases. This previously
available model has been updated to use the new milling constraints available in theDensity Model feature.
SHAPE OPTIMIZATION OF A TUNING FORK

Extending the Tuning Fork model, this example shows how to set up an Optimization
study to determine the prong length at which the fork vibrates at the standard concert
pitch, 440 Hz. This is achieved using the Deformed Geometry interface so that gradientbased optimization can be utilized.

114 |CHAPTER 1: RELEASE NOTESTOPOLOGY OPTIMIZATION AND VERIFICATION OF AN ACOUSTIC MODE
IN A 2D ROOMThis model has been updated to use the new milling functionality of the Density Modelfeature.

Backward Compatibility with Version 6.0
The Free Shape Boundary and Free Shape Shell behave differently in 3D, but the change
is limited to lines where the features intersect with Symmetry/Roller features.
Specifically, in previous versions, the continuity of the slope was not preserved atinternal points on such lines, but in version 6.1, the continuity of the slope ispreserved.

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Particle Tracing Module
New and Improved Functionality in Version 6.1
IMPROVED PSEUDORANDOM NUMBER GENERATIONThe Particle Tracing Module includes a variety of features that rely on pseudorandom
number generation (PRNG), such as the following:• Monte Carlo modeling of collisions between model particles and molecules of abackground gas• Brownian motion of small particles in a fluid• Motion of particles in a turbulent fluid• Boundary conditions that cause particles to be diffusively or isotropically reflected• Secondary particle emission at a specified probability• Conditional particle–wall interactions
For such features, the calls to pseudorandom number generators have been extensively
reviewed and revised. The new expressions are much less likely to incur unwanted
correlations between random numbers that should be completely uncorrelated. This
includes random forces acting on different particles, different components of certain
random forces, and different physics features or different instances of the same feature.
IMPROVED SAMPLING FROM THERMAL VELOCITY DISTRIBUTIONSThe Particle Tracing Module includes several features that sample the particle speed
from a distribution based on temperature when releasing or reflecting particles at asurface. This includes the Thermionic Emission particle release feature for the Charged
Particle Tracing interface, the Thermal velocity distribution type for the Inlet node, andthe Thermal Re-Emission boundary condition. The way in which values of the particle
speed are sampled from a distribution based on temperature is now more accurate. The
improvement should be most obvious when computing statistics for particles at theextreme low and high ends of the distribution when the sample size is large.
THERMAL VELOCITY DISTRIBUTION AVAILABLE FOR THE SECONDARYEMISSION

A new Thermal velocity distribution type is now available for the Secondary Emission
attribute of Wall and Axial Symmetry features. Accordingly, you can now sample

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secondary particles based on thermal velocity distribution when active particles hit awall.

New Applications in Version 6.1
MULTIPACTOR SATURATION

The multipactor effect is a resonance phenomenon in which an avalanche of secondary
electrons can be released within an RF cavity. This tutorial is a bidirectionally coupled,time-dependent model in which the space charge density of the emitted secondary
electrons and the effect of this space charge density on the electric potential in thecavity are computed, along with the electron trajectories. At sufficiently high spacecharge density, saturation occurs, meaning that the electrons are spread out by theirmutual electrostatic repulsion, slowing down some electrons before they can hit thecavity walls and causing the total population of electrons to reach a state of dynamic
equilibrium.
CASCADE IMPACTOR

This example simulates particles in a range of sizes that move through and get collectedin different levels of a cascade impactor. A cascade impactor is a particle separation
device consisting of multiple levels of collecting plates connected throughprogressively finer nozzles.

Important Fixes in Version 6.1
RELEASE FEATURE LIST IN PARTICLE COUNTER FEATURE

In version 6.0, when a release feature selected in the Release feature list of the Particle
Counter node was disabled, an error occurred. This has been fixed in version 6.1. The
selection automatically switches to All now, without any error message.
MAGNETOPHORETIC FORCE

The documentation for the Magnetophoretic Force node has been revised where aneasier way to evaluate derivatives of the magnetic field components is mentioned. Thismethod is useful when magnetic field components are available from other physics
interface but the derivatives of these components are not readily available.
IMPROVED PERFORMANCE FOR FORCE CALCULATION

Any force that applies to all domains can now be evaluated slightly faster. For such acase, in the Domain Selection, choose All domains rather than selecting Manual and thenPARTICLE TRACING MODULE|

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selecting all domains in the geometry. The performance improvement is only achieved
when All domains is selected in any feature calculating force.
DUPLICATING RELEASE FROM DATA FILE NODEIn version 6.0, the embedded or imported file was duplicated when the Release from
Data File node was duplicated. When the original Release from Data File node was used
to import another file, there was an error. Also, the duplicated node in some cases
completely overrode the original node without displaying any error message. This has
been fixed now. When you duplicate this node, the imported file will not be duplicated;
you will need to import the file into every duplicated node.
LINE PLOTS FASTER IN PARTICLE TRAJECTORIES PLOTIn version 6.1, the default of Maximum number of extra time steps rendered is changed
to All in the Particle Trajectories plot. Plotting Line, Ribbon, or Tube is now much fasterthan in version 6.0.

Backward Compatibility with Version 6.0 and Earlier
DUPLICATED RELEASE FROM DATA FILE NODE

If a model created using version 6.0 or earlier contains duplicated Release from Data
File nodes, it is recommended to delete these nodes, create new nodes, and import thefiles again, even if the same file is used in each node.

118 |CHAPTER 1: RELEASE NOTESP i pe Flo w M od u l e
New Functionality in Version 6.1
PIPE WALL HEAT TRANSFER

A new Pipe Wall Heat Transfer multiphysics coupling has been added to connect
domains modeled using the Heat Transfer interfaces and edges modeled using theHeat Transfer in Pipes or Nonisothermal Pipe Flow interfaces.
CORRECTION FOR PIPE BENDS

In the Pipe Mechanics interface, you can now specify correction factors for stiffness
and stress evaluation in pipe bends. To do this, you add the Bend subnode under Pipe
Cross Section.
STRESS EVALUATION USING REDUCED PIPE THICKNESSWhen specifying a Pipe Cross Section in the Pipe Mechanics interface, you can now
enter a reduced pipe thickness for the stress evaluation. This can be used when you are,for example, taking corrosion allowance into account.
LIBRARY OF PIPE GEOMETRIESIn the Part Libraries, the content of the Pipes folder in the COMSOL Multiphysics branch
has been augmented. The folder now contains parameterized geometries for thefollowing common piping parts: straight pipe, bend, reducer, and T-junction. These
geometries can be used for detailed analysis, using the fluid flow or structural
mechanics interfaces. Such a part can be inserted into a pipe system modeled using thePipe Flow or Pipe Mechanics interface, through the Pipe Connection or Structure-Pipe
Connection multiphysics couplings.
Because the new parts are more general in scope, the old straight_pipe andbent_pipe parts have been removed.

Updated Models in Version 6.1
MOLD COOLING

This model has been updated to use the Pipe Wall Heat Transfer multiphysics coupling.

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GROUND HEAT RECOVERYThis model has been updated to use Pipe Wall Heat Transfer multiphysics coupling.

120 |CHAPTER 1: RELEASE NOTES

Plasma Module
New Functionality in Version 6.1
INDUCTIVELY COUPLED PLASMA WITH RF BIAS INTERFACEThe new Inductively Coupled Plasma with RF Bias interface couples the Plasma, Time
Periodic and Magnetic Fields interfaces and is used to model inductively coupledplasma reactors with a periodic RF bias (also known as ICP or CCP reactors).
FREQUENCY-TIME PERIODIC STUDYThe Frequency-Time Periodic study is used to compute the periodic steady-state solution
for models using the Plasma, Time Periodic interface together with theelectromagnetic fields in the frequency domain. This study is available for the Plasma
Inductive Coupled Plasma with RF Bias interface.
ADD-IN TO ADD A PLASMA CHEMISTRY FROM A FILE

The new Plasma Chemistry add-in makes it possible to import a file that automaticallycreates a complete plasma chemistry. In the Model Builder, features like Electron
impact reactions, Species and others are automatically created from instructions you canspecify in a file. The following aspects of a plasma chemistry can be specified in the file:• Species properties including thermodynamic parameters• Electron impact reactions from cross section and rate constants• Heavy species reactions• Surface reactions
New models that use the Plasma Chemistry add-in are the following:• Model of an Argon/Chlorine Inductively Coupled Plasma Reactor with RF Bias
• Model of an Argon/Oxygen Inductively Coupled Plasma Reactor• Model of an Argon/Oxygen Capacitively Coupled Plasma Reactor
COUPLING THE PLASMA, TIME PERIODIC INTERFACE WITH HEATTRANSFER AND FLUID FLOW

It is now possible to coupled the Plasma, Time Periodic interface with the Heat
Transfer in Fluid and Laminar Flow interfaces. In the Model Inputs section of the Plasma
Model node, the Temperature, Absolute pressure, and Velocity fields can be linked to the

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Heat Transfer in Fluid and Laminar Flow interfaces. In the Heat Transfer in Fluid andLaminar Flow interfaces, the Fluid Properties and Fluid nodes can receive periodaveraged quantities computed in the plasma model, like the period-averaged density,
thermal conductivity, and dynamic viscosity.
The Heat Source feature now includes the option to receive the period-average heatsource for the gas computed in the Plasma, Time Periodic interface.
The new Model of an Argon/Chlorine Inductively Coupled Plasma Reactor with
RF Bias model demonstrates the couplings mentioned above.
INFLOW AND OUTFLOW FEATURES FOR THE PLASMA, TIME PERIODICINTERFACE

The Inflow and Outflow features in the Plasma, Time Periodic interface make it easy to
set boundary conditions for many species related to fluid inlets and outlets.
The new Model of an Argon/Chlorine Inductively Coupled Plasma Reactor with
RF Bias and Model of an Argon/Oxygen Capacitively Coupled Plasma Reactor
models use these features in the context of complex plasma chemistries.
NEW EQUILIBRIUM DISCHARGE INTERFACESThe Equilibrium Discharges interfaces have been replaced by three new interfaces:
Equilibrium Discharges, Out-of-Plane Currents; Equilibrium Discharges, In-Plane
Currents; and Equilibrium Discharges. The interfaces look mostly identical as before,
with the exception that the new Magnetic and Electric Fields interface is used in the
Equilibrium Discharges, In-Plane Currents interface. The choice of which interface to
use is now based on the plane for which the currents are to be computed.
The use of the Magnetic and Electric Fields interface increases numerical stability andsignificantly reduces computational time, as can be seen in the Plasma Pulsed Arc
model.
INCONSISTENT STABILIZATION

It is now possible to add isotropic diffusion for ions in the Inconsistent Stabilization
section of the Plasma, Time Periodic interface. This option is available when the Heavy
species selection is set to Base geometry.
For the Plasma interface, the isotropic diffusion for ions and electrons in theInconsistent Stabilization section is extended for when the Finite element, log formulation(linear shape function) and Finite element, log formulation (quadratic shape function) are
used.

122 |

CHAPTER 1: RELEASE NOTESTo enable the Inconsistent Stabilization section, click the Show More Options button andselect Stabilization in the Show More Options dialog box.

New and Updated Applications in Version 6.1
MODEL OF AN ARGON/CHLORINE INDUCTIVELY COUPLED PLASMAREACTOR WITH RF BIAS

This tutorial model shows how to prepare a model for an ICP or CCP reactor using
the new Inductively Coupled Plasma with RF Bias interface. A plasma chemistry forargon and chlorine is used, and strategies to model electronegative discharges are
discussed in the documentation. This model uses the new Plasma Chemistry add-in,which automatically creates plasma chemistries from a file.
MODEL OF AN ARGON/OXYGEN INDUCTIVELY COUPLED PLASMAREACTOR

This model solves for an ICP reactor with a mixture of argon and oxygen. The plasma
model is coupled with fluid flow and gas heating. Strategies to model electronegative
discharges are discussed in the documentation. This model uses the new add-in Plasma
Chemistry that automatically creates plasma chemistries from a file.
MODEL OF AN ARGON/OXYGEN CAPACITIVELY COUPLED PLASMAREACTOR

This model solves for an CCP reactor with a mixture of argon/oxygen. Strategies tomodel complex chemistries and electronegative discharges in the Plasma, Time
Periodic interface are discussed. This model uses the new Plasma Chemistry add-in,which automatically creates plasma chemistries from a file.
DRY AIR BOLTZMANN ANALYSISThis model solves the Boltzmann equation in the two-term approximation for a
mixture of nitrogen and oxygen that represents dry air. Electron transport coefficientsand source terms are computed by suitable integration of the electron energy
distribution function over electron impact cross sections. The documentation shows
how to prepare the electron energy distribution function to export so that it can beused in the Plasma interface. It is discussed what the data plasma fluid models need andhow this can be computed with the Boltzmann Equation, Two-Term Approximationinterface.

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PLASMA PULSE ARC AND PLASMA ARC MODELSThe Plasma Pulsed Arc and Plasma Arc models use the new Magnetic and Electric
Fields interface that combines the Magnetic Fields and Electric Currents interfaces.

Backward Compatibility with Version 6.0 and Earlier
There is a new version of the Plasma, Time Periodic interface. When opening models
created with version 6.0 and earlier, a warning sign appears saying, “This physics
interface is obsolete and will be removed in a future version. A new version of thephysics interface is available from the Add Physics window.” These models can still bechanged and will run as before, but it is encouraged to recreate the models using
version 6.1.

Backward Compatibility with Version 5.5 and Earlier
There are new versions of the following interfaces: Plasma; Drift Diffusion; Heavy
Species Transport; Inductively Coupled Plasma; Microwave Plasma; and Boltzmann
Equation, Two-Term Approximation. When opening models created with version 5.5
and earlier, a warning sign appears saying, “This physics interface is obsolete and will
be removed in a future version. A new version of the physics interface is available fromthe Add Physics window.” These models can still be changed and will run as before,
but it is encouraged to recreate the models using version 6.1.

124 |CHAPTER 1: RELEASE NOTESPorous Media Flow Module
New Functionality in Version 6.1
IMPROVED HANDLING OF FRACTURESIn the Darcy’s Law and Fracture Flow interfaces, the following improvements areavailable:• Fractures are now defined using phase-specific properties in the Fracture node. The
Fluid subnode describes the fluid properties, and the Fracture Material subnodeaccounts for the fracture properties, such as porosity or transmissivity.
• It is now possible to model Darcian or Non-Darcian flow in fractures.
• The fractures can be highly conductive, like open channels, or can be represented
by thin barriers.
• Fractures now also support the ideal gas and the linearized storage model.
FRACTURES FOR TRANSPORT OF DILUTED SPECIESA new Fracture node is now available in both the Transport of Diluted Species in
Porous Media and the Transport of Diluted Species in Fractures interfaces. The newnode is consistent with other fracture nodes for porous media transport, and it includes
two subnodes, Fluid and Fracture Material. The Fluid subnode describes the fluid,
velocity, and diffusion properties, and the Fracture Material subnode accounts for thefracture properties.
IMPROVEMENTS TO THE LEVEL SET INTERFACEIn the Level Set interface, a new Porous Medium feature now supports the functionality
to update the definition of the porosity in the Materials node. This feature is included
by default in the new Level Set in Porous Media interface includes as well as in the
Brinkman Equations, Two-Phase Flow, Level Set multiphysics interface.
STORAGE MODEL FOR UNSATURATED POROUS MEDIA

An option for the Storage model in the Unsaturated Porous Medium node has been
added for the Darcy’s Law interface. It is now possible to define storage as a functionof the liquid content.

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IMPROVEMENTS TO HYGROSCOPIC POROUS MEDIUM• The Moisture Flow multiphysics coupling has been updated so that the evaporation
rate variable computed by the Moisture Transport interface is accounted for in themass balance computed by the Brinkman Equations interface.
• The Open Boundary and Inflow boundary conditions are now applicable to exterior
boundaries adjacent to domains where a Hygroscopic Porous Medium feature is active.
USER-DEFINED PHASE TRANSITION

A User defined phase transition function in the Phase Change Material subnode is now
available for the Heat Transfer in Porous Media interface. This option makes it possible
to use an accurate phase change description from measured data.
THIN BARRIER MULTIPHYSICS COUPLING

The new Thin Barrier node for the Multiphase Flow in Porous Media multiphysics
interface makes it possible to add thin layers that act as a resistance for the flow fieldsof all phases without meshing through the layer’s thickness.
CLIMATE DATA: ASHRAE 2021

ASHRAE Weather Data 2021 has been integrated into COMSOL Multiphysics.
ASHRAE 2021 contains additional locations; there are more than 8500 stations in the2021 edition. You can select any of them in the Ambient Properties node. The databaseprovides typical climate data for the temperature, humidity, precipitation, and solar
radiation.
NEW PREDEFINED PLOTS

With the introduction of the new Add Predefined Plots feature, the number of default
plots that are produced has been reduced. Several plots that were default plots are now
instead optional and can be added from the Add Predefined Plots window. There arealso several new useful predefined plots.

New Models in Version 6.1
PHASE CHANGE IN A SEMI-INFINITE SOIL COLUMN — LUNARDINISOLUTION

In this new model, a heat-conduction problem with phase change in a porous material
is solved, and the results are compared with the analytical solution, also known as the
Lunardini solution. This is the first test case from the InterFrost project.

126 |CHAPTER 1: RELEASE NOTESRESIN TRANSFER MOLDING OF A WIND TURBINE BLADE

This example shows the modeling of a resin transfer molding (RTM) process for a windturbine blade using the Two-Phase Flow, Level Set, Brinkman Equations interface.
Resin is injected into a preform consisting of different composites with different
anisotropic permeabilities.

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Polymer Flow Module
New Functionality in Version 6.1
MULTIPHASE MATERIALS FOR MULTIPHASE FLOW COUPLINGSThe Two-Phase Flow, Level Set; Two-Phase Flow, Phase Field; and Three-Phase Flow, Phase
Field multiphysics couplings have a new option to obtain the effective material

properties from a Multiphase Material with built-in mixing rules. This option isespecially effective when coupling these multiphysics interfaces with other physics,
such as heat transfer or electrostatics, since the multiphase material will use appropriate
mixing rules for nonfluid material properties. In older versions, this would require you
writing user-defined expressions based on the volume fraction of each fluid phase tocompute the effective material properties used in each physics interface.
INELASTIC NON-NEWTONIAN MATERIAL PROPERTY GROUPS

Dedicated material property groups have been added for all available inelastic nonNewtonian models. The material property group contains all necessary material
parameters and the apparent viscosity expression. It picks up the shear rate from thefluid flow interface to define the dynamic viscosity in the Basic (def) material model bymeans of a synchronization rule. Thus, an inelastic non-Newtonian model can beselected directly by adding the corresponding Material Properties group as a subnodeto a material node.
CURING REACTION INTERFACEThe new default feature, No Flux, has been added to the physics interface.
NONISOTHERMAL VISCOELASTIC FLOWSThe Fluid Properties node in the Viscoelastic Flow interface now includes the option to
specify the temperature dependence of the material properties using a set of predefined
thermal functions.
The new Nonisothermal Flow multiphysics coupling can be used to couple the
Viscoelastic Flow and Heat Transfer in Fluids interfaces. The heat source,
corresponding to heating due to irreversible losses, can be accounted for by selecting
the Include irreversible losses check box.
A new Nonisothermal Flow, Viscoelastic Flow multiphysics interface has been addedfor convenient setup of nonisothermal viscoelastic flow models. It combines the128 |CHAPTER 1: RELEASE NOTESViscoelastic Flow and Heat Transfer in Fluids physics interfaces using a Nonisothermal
Flow multiphysics coupling node.
LICENSE UPDATE FOR PARAMETER ESTIMATIONThe Parameter Estimation study step, and the BOBYQA, Levenberg–Marquardt, and
IPOPT optimization solvers are now available with a Polymer Flow Module license.
IMPROVEMENTS TO THE LEVEL SET INTERFACEIn the Level Set interface, a new Porous Medium feature supports the functionality to
update the definition of the porosity in the Porous Matrix node. This node is included
by default in the new Level Set in Porous Media interface as well as in the Brinkman
Equations interface and the Two-Phase Flow, Level Set multiphysics coupling node.

New Models and Updated Models in Version 6.1
2D NON-NEWTONIAN SLOT-DIE COATINGThe model has been substantially reworked to use the new Multiphase Materials
functionality. It also now demonstrates how to use the Least-Squares Fit function toestimate material parameters from measured data.
RESIN TRANSFER MOLDING OF A WIND TURBINE BLADE

This example shows the modeling of a resin transfer molding (RTM) process for a windturbine blade using the Two-Phase Flow, Level Set, Brinkman Equations interface.
Resin is injected into a preform consisting of different composites with different
anisotropic permeabilities.

Backward Compatibility with Version 6.0
Non-Newtonian inelastic material models that were added in older versions will not beable to define the dynamic viscosity in the Basic (def) material model.

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Ray Optics Module
New and Improved Functionality in Version 6.1
FLUENCE RATE CALCULATION

A new domain accumulator feature for computing fluence rate, Fluence Rate
Calculation, is now available in version 6.1. Fluence rate is defined as the amount ofradiation that would hit a small spherical detector at any location in the simulation
domain, divided by the cross-sectional area of such a detector.
OPTICAL MATERIAL LIBRARY UPDATES

Fused silica and i-line glass materials from Ohara Corporation have been added to the
Optical material library. Compared to other types of glass, fused silica and i-line glasses
generally have greater transmittance at ultraviolet (UV) and near-UV wavelengths.
IMPROVED PSEUDORANDOM NUMBER GENERATIONThe Ray Optics Module includes a variety of features that rely on pseudorandom
number generation (PRNG), such as the following:• Monte Carlo modeling of light extinction in particle-laden media• Diffuse and isotropic scattering• Surface-normal perturbations for modeling rough boundaries• Conditional ray-boundary interactions
For such features, the calls to pseudorandom number generators have been extensively
reviewed and revised. The new expressions are much less likely to incur unwanted
correlations between random numbers that should be completely uncorrelated. This
includes random boundary conditions acting on different rays, as well as unwanted
correlations between different randomly generated vector components.
OPTION TO ONLY STORE ACCUMULATED VARIABLES IN SOLUTION

Depending on your application, the accumulated variables (such as the deposited ray
power or fluence rate within a domain) might be more valuable information than theposition and direction of individual rays. To reduce file size, you now have the option
to only retain the accumulated variables in the solution while discarding the degrees of
freedom associated with the rays.

130 |CHAPTER 1: RELEASE NOTESNew And Updated Applications in Version 6.1
ANNULAR ULTRAVIOLET REACTOR

This tutorial model demonstrates how to compute the volumetric fluence rate in a UVreactor. The geometry is the annular fluid surrounding a cylindrical lamp. The effectof reflection at the reactor walls on the radial fluence rate distribution is considered.
ANNULAR ULTRAVIOLET REACTOR WITH PARTICLE TRACING

In this example, a simple UV water purification reactor is modeled using a combinationof ray tracing, computational fluid dynamics (CFD), and Lagrangian particle tracking.
First, the volumetric fluence rate is accumulated along rays released from the surfaceof the UV lamp using the Geometrical Optics interface. Then, the fluid velocity in thereactor is solved for. Finally, particles are traced along the fluid velocity streamlines
while the fluence rate along these particle trajectories is integrated using an Auxiliary
Dependent Variable. This example requires the CFD Module and the Particle Tracing
Module.
RAY OPTIC MODELING OF A FRESNEL LENSThis tutorial model shows how a Fresnel lens can be designed from a plano-convex lens
as a way to reduce thickness. Here, the collimation property of a Fresnel lens ismodeled.
PETZVAL LENS STOP ANALYSIS WITH SURFACE-TO-SURFACE RADIATIONThis tutorial model has been updated to improve the accuracy of the calculation of
surface-to-surface radiation. This improvement is done by covering a gap between thevacuum window and the thermal shroud window using a vacuum chamber.

Important Fixes in Version 6.1
REFRACTIVE INDEX VALUE AND GAUSSIAN BEAM FEATURE

In version 6.0, when the imaginary part of the refractive index of a material was
nonzero, an error appeared in the Gaussian Beam node. This error has been fixed sothat the node now only takes into account the real part of the refractive index value.
CORRECTED INITIALIZATION OF SEARCH DIRECTION OF RAYS

In version 6.0, when the initial position of a beam created using either the Gaussian
Beam or Solar Radiation feature fell exactly on the surface or boundary of the geometry,

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the direction of search for other boundaries and surfaces did not always align with thebeam propagation direction. This has been now been fixed.
DUPLICATING RELEASE FROM DATA FILE NODEIn version 6.0, the embedded or imported file was duplicated when the Release from
Data File node was duplicated. When the original Release from Data File node was used
to import another file, an error occurred. Also, the duplicated node in some cases
completely overrode the original node without producing an error. This has beencorrected; now, when you duplicate this node, the imported file will not be duplicated.
You will need to import the file into every duplicated nodes.
LINE PLOTS FASTER IN RAY TRAJECTORIES PLOTIn version 6.1, the default of the Maximum number of extra time steps rendered setting
is changed to All in the Ray Trajectories plot. Plotting using the Line, Ribbon, or Tubestyles is now much faster than in version 6.0.

Backward Compatibility with Version 6.0 and Earlier
DUPLICATED RELEASE FROM DATA FILE NODE

If a model created using version 6.0 or earlier contains duplicated Release from Data
File nodes, it is recommended to delete these nodes, create new nodes, and import thefiles again, even if same file is used in each node.

132 |CHAPTER 1: RELEASE NOTESRF Module
New Functionality in Version 6.1
CONDUCTIVE DOMAINS

When conductive domains contain many boundaries, it is often cumbersome to apply
the boundary condition to all of them individually. The Perfect Electric Conductor and
Impedance Boundary Condition domain features can be directly applied to the
conductive domain without having to locate all of the boundaries or manually remove
the interior domain.
ELECTROSTATIC DISCHARGE AND LIGHTNING PULSESThe Lumped Port and Edge Current features in the Electromagnetic Waves, Transientinterface support predefined and parameterized temporal pulse functions to describe
electrostatic discharge (ESD) and lightning that may cause detrimental effects toelectronic components. For convenience of inspection, the pulse shapes can beinstantly plotted before running the simulation to ensure the choice of function
parameters is suitable.
QUICK MESH REFINEMENT ON FAR-FIELD CALCULATION BOUNDARIESIn the physics-controlled mesh settings of the Electromagnetic Waves, Frequency
Domain interface, the Add far-field boundary layers option is provided. When selected,
a boundary layer mesh with a thickness of 1/40 of the default maximum mesh size iscreated in the far-field calculation boundaries adjacent to the selection of scatteringboundary conditions or perfectly matched layers. This boundary layer mesh helps
obtaining more accurate far-field analysis results such as total radiated power and radarcross section (RCS).
FOUR-PORT NETWORKThe Electromagnetic Waves, Frequency Domain interface now includes the Four-Port
Network boundary condition, which characterizes the response of a four-port network

component using S-parameters. You can import a Touchstone file to describe thephysical behavior and response of a four-port device or system through four-portboundaries without addressing a complicated geometry.

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DIELECTRIC SCATTERING WITH THE ELECTROMAGNETIC WAVES,
BOUNDARY ELEMENTS INTERFACE

It is now possible, in the Scattered field Formulation for the Electromagnetic Waves,
Boundary Elements interface to solve problems involving multiple dielectric scatterers
embedded in an infinite domain.
LUMPED PORT IN THE ELECTROMAGNETIC WAVES, BOUNDARYELEMENTS INTERFACEThe Lumped Port feature is available for the Electromagnetic Waves, Boundary
Elements interface to excite or terminate metallic structures such as dipole antennas.
SYMMETRY PLANE

The Symmetry Plane feature simplifies the definition of perfect electric conductor(PEC) and perfect magnetic conductor (PMC) symmetry planes. This feature is usedinstead of the Perfect Electric Conductor and Perfect Magnetic Conductor boundary
conditions when reducing the model size from symmetry considerations.
Furthermore, the information about the type and location of the Symmetry Plane
features is used when calculating far fields and when defining analytical Port mode
fields.
WEAK FORMULATION PORT OPTION

When expanding the electric field on a port boundary, the new weak port formulation
adds a scalar dependent variable for the expansion coefficient (the S-parameter) andthen solves for the S-parameters and the tangential electric field on the boundary using
only a weak expression. Since no constraints are used, this formulation completely
removes the constraint elimination step when solving.
This new port formulation replaces the other constraint-free port formulation that was
introduced in version 6.0.
LAYERED IMPEDANCE BOUNDARY CONDITION

The Layered Impedance Boundary Condition is an extension of the Impedance Boundary
Condition that makes it possible to model a sequence of geometrically thin layers on topof a substrate. It is used on exterior boundaries where the field is known to penetrate
only a short distance outside the boundary. In brief, this feature combines a Layered
Transition Boundary Condition with an Impedance Boundary Condition.
This new feature is available for the Electromagnetic Waves, Frequency Domaininterface.

134 |CHAPTER 1: RELEASE NOTESLINEARLY POLARIZED PLANE WAVE BACKGROUND FIELD IN 2D
AXISYMMETRY

For 2D axisymmetry, there is a new background field, the Linearly Polarized Plane Wave
type. Here, the plane wave is expanded in a series of Bessel functions. This functionality
makes it possible to very efficiently model the scattering of plane waves fromrotationally symmetric objects.
FEM-BEM MULTIPHYSICS COUPLING

To simplify the setup of models using both the Electromagnetic Waves, Frequency
Domain and Electromagnetic Waves, Boundary Elements interfaces, theElectromagnetic Waves, FEM-BEM multiphysics interface can be selected in the
Model Wizard.
This multiphysics interface adds the two physics interfaces and the Electric Field
Coupling multiphysics coupling feature to the new model.
COVARIANT FORMULATION IN 2D AXISYMMETRY

In the 2D axisymmetric formulation, it is beneficial to formulate the out-of-planedependent variable as = rE  ,referred to as the covariant formulation. Here,  is the dependent variable, and theout-of-plane electric field component is calculated asE =   r .
The covariant formulation now has better performance in terms of numerical stability
and accuracy. In contrast with previous versions, eigenfrequency simulations can now
return a different number of eigenfrequencies. However, the returned solutions havebetter accuracy, and there are many fewer spurious solutions returned.
This formulation is used for all study types, except Mode Analysis and Boundary Mode
Analysis.
SKIN DEPTH CALCULATORThe Skin Depth Calculator can be used to compute skin depth before performing a fullmodel computation. This functionality is useful when setting up the physics andboundary conditions.

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The calculator is available in the settings window of the Impedance Boundary Condition,
Transition Boundary Condition, Layered Impedance Boundary Condition and Layered
Transition Boundary Condition features.
PLOTTING OF ANALYTIC PORT MODE FIELDS BEFORE COMPUTATIONFor Rectangular, Circular, and Coaxial Port types, it is now possible to plot and inspect
the mode field before computing the full solution. This is useful for correctly defining
the other boundary conditions used in the model.
UPWIND FLUX OPTION FOR THE ELECTROMAGNETIC WAVES, TIMEEXPLICIT INTERFACEThe Flux type parameter in the Wave Equations node for the Electromagnetic Waves,
Time Explicit interface now also includes the Upwind flux option. This option cansometimes be useful to improve S-parameter calculations that could have low accuracy
due to overdissipation around perfect electric conductor (PEC) edges, when using thedefault Lax-Friedrichs flux parameters.
PERIODIC PORT REFERENCE POINT

The Periodic Port Reference Point subnode has been simplified to only allow theselection of a single reference point.
NEW DEFAULT COLOR TABLE WHEN ADDING PLOTS

When adding a new 2D or 3D plot, the created plot will use the RainbowLight color
table by default.

New and Updated Models in Version 6.1
MODELING OF A DIFFERENTIAL MICROSTRIP LINEA differential line is composed of two transmission lines excited by two out-of-phasesignals. This configuration is known to be useful to enhance the signal-to-noise ratio.
The model example shows how to set up differential and single-ended microstrip lines
using TEM-type ports. The impact on computed S-parameters due to a fictitious noise
source is demonstrated for each microstrip line configuration, respectively.
ELECTROSTATIC DISCHARGE (ESD) TEST OF A PCBThis example demonstrates how an ESD event causes a logic error in the microchip ona PCB board. The ESD current is based on the extended human body model (HBM)
and is predefined in the Lumped Port feature.

136 |CHAPTER 1: RELEASE NOTESLIGHTNING-INDUCED VOLTAGE OF A WIRE IN AN AIRPLANE

This model demonstrates how to compute the induced voltage of a wire loop inside anairplane under different electromagnetic shielding conditions. The wing of the airplaneis struck by a lightning current pulse defined in the Edge Current feature.
LIGHTNING-INDUCED VOLTAGE OF AN OVERHEAD LINE OVER LOSSYGROUND

This model shows how to calculate the lightning-induced voltage of an overhead line
over lossy ground. Lightning channels with different inclinations are considered. The
effect of soil conductivity is also shown.
CLOAKING OF A CYLINDRICAL SCATTERER WITH GRAPHENE

In this model, a cloaking method is introduced using an electrically tuned monolayerof graphene. We will show that when a cylindrical dielectric scatterer is covered ingraphene, the scattering cross section is greatly reduced at the designated frequency,
making it electromagnetically invisible. This model aims to demonstrate the use of the
Linearly polarized plane wave Background wave type option in a 2D axisymmetric model.
MICROWAVE OVENThis model has been updated to use the new Symmetry Plane feature.
DIPOLE ANTENNAThis model has been updated to use the domain Perfect Electric Conductor feature.
DIPOLE ANTENNA WITH A QUARTER-WAVE COAXIAL BALUN

This model has been updated to use the domain Perfect Electric Conductor feature.
CAR WINDSHIELD ANTENNA EFFECT ON A CABLE HARNESSThis model has been updated to use the domain Perfect Electric Conductor feature.
DOUBLE-RIDGED HORN ANTENNAThis model has been updated to use the domain Perfect Electric Conductor feature.
SIMULATING ANTENNA CROSSTALK ON AN AIRPLANE’S FUSELAGE

This model has been updated with the new airplane geometry.
MICROSTRIP PATCH ANTENNAThis model has been updated to use the Array Factor dataset.

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MODELING OF A PHASED ARRAY ANTENNAThis model has been updated to use the Array Factor dataset.

Backward Compatibility with Version 6.0 and Earlier
COVARIANT FORMULATION

In 2D axisymmetry, for all studies except Mode Analysis and Boundary Mode Analysis, thecovariant formulation is used (see Covariant Formulation in 2D Axisymmetry).
Thereby, Ephi is not a dependent variable. To get the correct out-of-plane electricfield component, the variable emw.Ephi should be used. In this name, it is assumed
that the dependent variable has been given the name E and that the tag for the physics
interface is emw.
NEW DEFAULT VALUE FOR THE RELATIVE PERMITTIVITY, HIGHFREQUENCY PARAMETER

The default value for the Relative permittivity, high frequency parameter, epsilonInf,
has changed from From material to User defined.

138 |CHAPTER 1: RELEASE NOTESRotordynamics Module
New Functionality in Version 6.1
MODELING OF ROTOR RUB

Contact between a rotor and its housing can be modeled using the new Rotor Rub nodein the Beam Rotor interface. Optionally, friction between the parts can be included.
CHANGED UI FOR HYDRODYNAMIC BEARINGThe settings for the Hydrodynamic Bearing interface have been changed to be morelogical. The Cavitation section has been removed, and cavitation is now selected as an
option in the Fluid type list.
CRITICAL SPEEDS IN CAMPBELL DIAGRAMSThe Campbell diagrams have been augmented with markers, showing the critical
speeds of the rotor.
RESULTS IN LOCAL DIRECTIONS

For details, see Results in Local Directions in the release notes for the Structural
Mechanics Module.
NEW INPUT OPTIONS FOR NONISOTROPIC ELASTIC MATERIALSFor details, see Results in Local Directions in the release notes for the Structural
Mechanics Module.
RIGID DOMAIN RENAMED TO RIGID MATERIAL

For details, see Rigid Domain Renamed to Rigid Material in the release notes for the
Structural Mechanics Module.
REDUCED NUMBER OF DEFAULT PLOTS

For details, see Reduced Number of Default Plots in the release notes for the Structural
Mechanics Module.
PREVIEW PLOT FOR RAYLEIGH DAMPING

For details, see Preview Plot for Rayleigh Damping in the release notes for the
Structural Mechanics Module.

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REMOVED SECTION IN PHYSICS INTERFACE SETTINGS

For details, see Removed Section in Physics Interface Settings in the release notes for
the Structural Mechanics Module.

New Models in Version 6.1
TOPOLOGY OPTIMIZATION OF A STEP THRUST BEARINGIn this tutorial model, a step thrust bearing is topology optimized to maximize thebearing capacity. A step thrust bearing consists of a stepped bearing surface on which
the end of the shaft rotates. The entire assembly is submerged in a lubricant.
The model shows that initializing the optimization with a nonuniform design can
result in local minima with a specific number of steps.
SHAPE OPTIMIZATION OF A STEP THRUST BEARINGIn this tutorial model, a step thrust bearing is shape optimized to maximize the bearing
capacity. A step thrust bearing consists of a stepped bearing surface on which the endof the shaft rotates. The entire assembly is submerged in a lubricant.
The resulting design shows the optimal shape of the steps. The model also includes aparametric sweep over the number of steps to identify the optimal number.

140 |CHAPTER 1: RELEASE NOTESStructural Mechanics Module
New Functionality in Version 6.1
SOLID MECHANICS INTERFACE IN 1D AND 1D AXISYMMETRY

The Solid Mechanics interface is now also available for components with 1D and 1D
axisymmetric geometries. This is mainly interesting for multiphysics cases. Several
multiphysics interfaces and multiphysics couplings are available in 1D and 1D
axisymmetry. Some features and material models that are inherently multiaxial are notavailable in the 1D versions of the interface.
TESTING OF MATERIAL MODELS

A new feature, Test Material, has been added to the Solid Mechanics interface. With
this feature, it is possible to set up single-element tests for various scenarios like uniaxial
or biaxial tension. The purpose is to test and verify the behavior of a material model
for a given set of material properties. For material models with an explicit timedependence, the test study can be time dependent.
MATERIALS ON BOUNDARIES OF SOLIDS

In the Solid Mechanics interface, a new feature called Thin Layer has been introduced.
You can use it to add material models on interior and exterior boundaries. Mostdomain material models that would also be relevant for a thin layer are available. With
the Composite Materials Module, a thin layer can itself be multilayered. There aredifferent formulations of the thin layer materials, depending on the assumed
kinematics.
PHYSICS INTERFACE FOR WIRESA new physics interface dedicated to the analysis of wires and cables has been added:
The Wire interface is available with the Structural Mechanics Module and Multibody
Dynamics Module.
MULTIPHYSICS INTERFACES FOR THIN-FILM DAMPING

Two new multiphysics interfaces for modeling thin-film damping have been added:
Solid Thin-Film Damping and Shell Thin-Film Damping. They combine a Thin-Film
Flow interface with a Solid Mechanics or Shell interface, respectively. The couplings
are made through the new Structure Thin-Film Flow Interaction and Shell Thin-Film Flow
Interaction multiphysics couplings.

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As an effect of this more general approach, the Thin-Film Damping feature in the Solid
Mechanics interface has been retired. It will still appear if you open an old model that
contains such a feature, but you can no longer add it. Consider replacing it using the
new modeling paradigm, since it will only be available for a few more releases and is
no longer actively maintained.
MAGNETOSTRICTION INTERFACE CHANGESThe Magnetostriction multiphysics interface has been split into two different
interfaces: Piezomagnetism and Nonlinear Magnetostriction.
DEAD LOADS IN LINEARIZED BUCKLING ANALYSIS

In a linearized buckling study, you can now separate the loads into those that are
assumed to be independent of the load factor (dead loads) and those that areproportional to the load factor (live loads). To mark a certain load as being a dead load,
you go to the Linear Buckling section in the settings for that load feature. This section
is only shown when Advanced Physics Options is enabled. There are also special settings
in the Linear Buckling study step to control the different load cases.
THICKNESS OF SHELLS AND MEMBRANES CAN CHANGE OVER TIME

In the Shell and Membrane interfaces, the Thickness and Offset node has been
augmented by a subnode called Thickness Change. There, it is possible to enter a rate ofthickness change. The purpose is to model phenomena like wear, corrosion, andelectrodeposition.
WEAR MODELING IN SHELL AND MEMBRANE INTERFACES

A new Wear subnode has been added to the Contact node in the Shell and Membraneinterfaces. With this feature you can model thickness reduction and corresponding
changes in contact force distribution caused by wear. The functionality is similar towhat was already available in the Solid Mechanics interface.
NEW DISCRETIZATION SETTING FOR WEAR

When the offset-based wear formulation is used, you can now select the type of shapefunction that is used to describe the offset field. This is done in the new Discretization
section in the Wear node.
CONTINUITY USING NITSCHE’S METHOD

In the Continuity node in the Solid Mechanics and Multibody Dynamics interfaces, you
can now select between three different methods for enforcing the continuity
conditions. In addition to using pointwise or weak constraints, a new formulation

142 |CHAPTER 1: RELEASE NOTES

based on Nitsche’s method is also available. The main advantage with the new method
is that there is no need for constraint elimination, since it only adds terms to thestiffness matrix.
COMPONENT MODE SYNTHESIS IMPROVEMENTS• Component mode synthesis (CMS) is now also available for the Shell interface.
• There are several improvements to the usability of the CMS functionality withrespect to how different features in the physics interfaces are treated.
• The Component subnode under Reduced Flexible Components has been renamed toComponent Definition.
NEW SEARCH METHOD FOR CONTACT ANALYSIS

A new search method for finding the distance between contacting boundaries has been
implemented. It is significantly faster than the previous methods, in particular for large
3D models. The new method, Hierarchical, is now the default search method in thesettings for a Contact Pair. The old search methods have been renamed to better reflect
their properties. The performance has been improved for these methods as well.
CONTACT USING NITSCHE’S METHOD

For contact between solid objects, it is now possible to select Nitsche as Contact method.
This method does not suffer from the introduction of an arbitrary stiffness, as in the
penalty method, and still no extra degrees of freedom are required. The Nitsche
method is robust but can be more costly because it produces a nonsymmetric stiffness
matrix.
NEW FORMULATION FOR CONTACT EQUATIONS

The formulation for the contact equations has been improved for all contact methods.
In particular, a reduced Jacobian is now used by default. You can control the assemblyof the Jacobian through the Jacobian contribution control in the Advanced section of theContact settings. Select Legacy to revert to the version 6.0 behavior.
IMPROVED SUPPORT FOR SELF-CONTACT

If you make the same selection for the source and destination in a Contact Pair node, aformulation of the contact conditions that is fully symmetric between source anddestination boundaries is used.

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IMPROVED FORMULATION FOR CONTACT IN SHELL AND MEMBRANE

The contact mapping is now done from the actual top and bottom surfaces of thestructural elements, enabling a correct area scale for thick, highly curved shells.
POSSIBLE TO TRIGGER A CUTBACK IN THE SOLVER FOR ALL CONTACTMETHODSThe Trigger Cutback section is now available for all contact methods. By setting anappropriate cutback criterion, you can force the solver to go back and start with asmaller parameter or time step, rather than spending many iterations on a solution thatis far from convergence.
BASE EXCITATION

A new node at the global level, Base Excitation, has been added to the structural
mechanics interfaces. The purpose is to handle the case where all support points
experience a common acceleration history. Base excitation can be used for any dynamic
study type, but it is most important for the modal-based procedures where it is notpossible to directly prescribe a nonzero acceleration of displacement.
GRAVITY AND LINEARLY ACCELERATED FRAME

The Gravity node has been changed to be a global feature in all structural mechanics
interfaces. The reason is that gravity is almost always applied to the entire structure. A
new node, Linearly Accelerated Frame, makes it possible to prescribe nonuniform
inertial loads.
LOADS GIVEN AS RESULTANT

For a Boundary Load or Point Load, it is now possible to give the total load as a force
and moment resultant. To use such a load, select Resultant from the Load type list. This
option is available in the Solid Mechanics, Multibody Dynamics, and Layered Shellinterfaces.
For Point Load, there is now also the possibility to set Load type to either Force per pointor Total force.
The difference between a total force and a resultant is that in the former case, the given
value is simply divided by the number of selected points (or boundary area) before itis evenly distributed. A resultant implies a certain spatial distribution of the loads.
RESULTS IN LOCAL DIRECTIONS

By adding a Local System Results node in a Solid Mechanics, Multibody Dynamics, orSolid Rotor interface, you can get access to a number of result variables expressed in a

144 |CHAPTER 1: RELEASE NOTES

given coordinate system. This includes displacements, velocities, accelerations, stresses,
strains, and material properties.
EVALUATION OF WELD STRESSES IN THE SHELL INTERFACE

When two boundaries with shell elements are joined using the Edge to Edge connectionin the Shell interface, it is possible to define the connection as a weld and to evaluate
weld-specific stress results. Three types of welds can be defined: single-sided fillet weld,
double-sided fillet weld, and butt weld.
MOMENT AND SHEAR FORCE DIAGRAMS FOR BEAMS

In the Beam interface, a capability to draw moment and shear force diagrams has been
included. Such section force diagrams can be added from the Add Predefined Plotwindow. The section force diagrams take the load distribution into account, so thateven with a very coarse mesh, the diagrams are more or less exact.
A set of new section force variables, called distributed section forces has been added tofacilitate this. The variable names are the same as for the standard section forces but
appended by _d, for example, beam.Myl_d.
STANDARD CROSS SECTIONS FOR TRUSS ELEMENTS

In the Truss interface, the Cross-Section Data node has been augmented by an option
for defining the element cross section by geometrical properties. The available crosssections are the same as in the Beam interface, that is, Rectangle, Box, Circular, Pipe,
H-profile, U-profile, T-profile, C-profile, and Hat.
SELECTION OF SIDE FOR SHELL CONNECTIONSIn the Edge to Edge, Edge to Boundary, and Boundary to Boundary connections in the
Shell interface, it is now possible to select a through-thickness location (top, bottom,
or midsurface) as the reference for the connection.
NEW INPUT OPTIONS FOR NONISOTROPIC ELASTIC MATERIALSIn the Linear Elastic Material and Layered Linear Elastic Material nodes, there are new
input options for material properties:• A new class of material symmetries has been added, called Crystal. It facilitates the
input of elasticity properties for seven different crystal systems, such as Cubic (3constants) and Hexagonal (5 constants). This option requires the Structural
Mechanics Module or the MEMS Module.

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• For an orthotropic material, it is possible to select the special case Transversely
isotropic, in which case five material constants are required.
• For an anisotropic material, you can now choose whether to enter an elasticity
matrix or a compliance matrix.
MULTIPLICATIVE FORMULATION FOR PIEZOELECTRICITY

For the Piezoelectric Material, a new formulation has been implemented in which theinelastic (piezoelectric) strains under geometric nonlinearity are removed from thetotal strains through multiplicative decomposition. The formulation is controlled by
the Use multiplicative formulation check box. When selected, any study will be forced
to be geometrically nonlinear.
CELL PERIODICITY CAN CREATE MATERIAL DATA ON COMPLIANCE FORM

When you select Average stress as Periodicity Type in Cell Periodicity, it is now possible
to create an average compliance matrix. This is an effect of the Linear Elastic Material
setting now allowing input to be included on the compliance form.
EXTENDED BUILT-IN MATERIAL

The built-in Structural Steel material has been augmented so that material properties
are temperature dependent. There is also material data for a wide range of nonlinear
material models.
LIBRARY OF PARTS FOR HOMOGENIZATION OF MICROSTRUCTURESIn the Part Library, a new folder called Representative Volume Elements has been added
to the COMSOL Multiphysics branch. It contains a number of parameterized geometries
for common microstructures, like fiber and particulate composites. These geometries
can, for example, be used to compute effective material properties using therepresentative volume element (RVE) method. The Cell Periodicity node in the Solid
Mechanics interface is designed for this.
RELEASED DEGREES OF FREEDOM IN RIGID CONNECTOR

It is now possible to specify that there is no connection in a certain direction for a rigid
connector. The direction can be specified in a local coordinate system, so that it, forexample, can be the radial direction from a certain point. You specify this behavior in
the new Released Degrees of Freedom in the settings for the Rigid Connector node.
SINGULARITY SUPPRESSION FOR TWO-POINT RIGID CONNECTOR

When a rigid connector has a selection that consists of only two points, it is now
possible to add a spring type condition to suppress the rotational singularity that could

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occur. The setting for this is in the Advanced section in the settings for the Rigid
Connector. The Add rotational stiffness for two-point selection check box is shown whenthe Include consistency checks check box is cleared.
LIMITED DISPLACEMENT IN TRUSS INTERFACEIn the Prescribed Displacement node in the Truss interface, there is a new option,
Limited Displacement. This type of boundary condition limits the displacement in acertain direction to a given maximum value. The Prescribed Displacement node has
been redesigned in order to accommodate this.
CORRECTION FOR PIPE BENDS

In the Pipe Mechanics interface, you can now specify correction factors for stiffness
and stress evaluation in pipe bends. To do so, you add the Bend subnode under Pipe
Cross Section.
STRESS EVALUATION USING REDUCED PIPE THICKNESSWhen specifying a Pipe Cross Section in the Pipe Mechanics interface, you can now
enter a reduced pipe thickness for the stress evaluation. This can be used when, forexample, taking corrosion allowance into account.
LIBRARY OF PIPE GEOMETRIESIn the Part Library, the content of the Pipes folder in the COMSOL Multiphysics branch
has been augmented. The folder now contains parameterized geometries for thefollowing common piping parts: straight pipe, bend, reducer, and T-junction. These
geometries can be used for detailed analysis using the Solid Mechanics or Shellinterface. Such a part can be inserted into a pipe system modeled using the Pipe
Mechanics interface, through the Structure-Pipe Connection multiphysics coupling.
Because the new parts are more general in scope, the old straight_pipe andbent_pipe parts have been removed.
NEW FORMULATION OF RIGID MOTION SUPPRESSION

The rigid motion suppression constraints are now applied in an average sense rather
than at arbitrary points. The advantage is that the visual impression of the deformation
shape is more intuitive.
IMPROVED PERFORMANCE FOR RANDOM VIBRATION EVALUATIONThe operators used for the evaluation of random vibration results have been optimized
and now exhibit significantly better performance.

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RIGID DOMAIN RENAMED TO RIGID MATERIALThe Rigid Domain material model has been renamed to Rigid Material in all physics
interfaces. The purpose is to emphasize that this is a material model with the same
status as other material models.
REDUCED NUMBER OF DEFAULT PLOTS

With the introduction of the new concept of predefined plots, the number of default
plots that are always produced by the structural mechanics interfaces has been reduced
significantly. Several plots that were default plots are now instead optional and can be
added from Add Predefined Plot window. There are also several new useful predefinedplots.
PREVIEW PLOT FOR RAYLEIGH DAMPING

In the Damping, Layered Damping, and Mechanical Damping nodes, it is now possible tocreate a preview plot that shows the damping as a function of frequency when data forRayleigh damping has been given.
PREVIEW PLOT FOR THICKNESS AND OFFSETIn the Thickness and Offset nodes in the Shell and Membrane interfaces, it is now
possible to create a preview plot that shows how the given inputs are interpreted.
NEW OPTION FOR GENERATION OF MATERIAL DATA IN CELLPERIODICITY

When creating material data from a Cell Periodicity node, you can now choose between
the two actions Create Material by Reference and Create Material by Value. The new
second option makes it possible to store material data in a file that can be used in othermodels.
GROUPING OF ODE VARIABLES IN SOLVER

In each Rigid Connector and Attachment node, a set of ordinary differential equation(ODE) degrees of freedom are created, representing the translation and rotation. Up
to version 6.0, each of these nodes would add two or three nodes under Dependent
Variables in the solver sequence. For models with many such features, this list could
become long. From version 6.1, the default is that such variables are grouped together
instead.
You can control whether or not to use the grouping. This can be done in two places.
The default behavior can be controlled from the Advanced Settings section in the148 |CHAPTER 1: RELEASE NOTES

settings for the physics interface. This section is visible if Advanced Physics Options is
active.
The default behavior can, however, be overridden for each individual Rigid Connector
or Attachment node, by using a selection in the Advanced section in the feature itself.
When opening an old model, the grouping will be turned off in order to maintain fullcompatibility with the previous version. When building a model using the API, thenew default will be used. This is true even if, for example, a Java® file created from anolder version is used. If you want to achieve full backward compatibility using the API,
you need to add two lines similar tomodel.component("comp1").physics("solid").
prop("AdvancedSettings").set("GroupPhysOdesRc", false);
model.component("comp1").physics("solid").
prop("AdvancedSettings").set("GroupPhysOdesAtt", false);

There are subtle differences in how the solver handles time stepping and convergence
depending on whether dependent variables are grouped or not. With grouping, theODE variables will be assigned less weight when compared with, for example, thedisplacement field, as long as no other settings are changed.
CHANGED DEFAULT FOLDLINE ANGLE

The default foldline angle in the Shell interface has been reduced to 0.001 rad in orderto reduce the risk of artificial stiffening.
NEW OPTION WHEN CONNECTING SHELLS AND SOLIDS

When connecting a shell or membrane boundary to a solid domain boundary, using
the Solid-Thin Structure Connection multiphysics coupling, you can now select for which
physics interface the constraints are generated. If the Connection type is Sharedboundaries or Parallel boundaries, you can make this selection in the new Advanced
section.
RESTRUCTURED REDUCED-ORDER MODEL STUDIESWhen one of the three reduced-order model studies (Frequency Domain, Modal
Reduced-Order Model; Time Dependent, Modal Reduced-Order Model; or Frequency
Domain, AWE Reduced-Order Model) is selected, the generated studies have a structurethat differs from previous releases. One study (Frequency Domain or Time Dependent) is
no longer needed. Instead, subnodes with the same names are created under the Model
Reduction study step.

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NODAL VERSION OF SHELL NORMAL CONSTRAINTS

In the Advanced Settings section in the Shell interface, you can now select whether theconstraints on the rotation around the normal are added as nodal or elemental
constraints.
MULTIPLICATIVE STRAIN DECOMPOSITION IN SHELL AND PLATE
INTERFACES

When modeling using geometric nonlinearity, the inelastic strains are now removed bymultiplicative decomposition in the Shell and Plate interfaces.
LIMITATIONS OF SELECTIONS ON AXIS OF ROTATION

For 2D axisymmetric components, it is no longer possible to select a line on the axisof rotation for a number of features. For the Shell and Membrane interfaces, such lines
can no longer be part of the physics selection. For Solid Mechanics, a number ofboundary conditions that are not relevant on the axis of rotation can no longer include
it in the selection.
REMOVED SECTION IN PHYSICS INTERFACE SETTINGSThe Reference Point for Moment Computation section has been removed from thesettings for all structural mechanics interfaces. The values of the properties are now
always set in the feature under Results where they are used.
MISCELLANEOUS• When using a strain-based mixed formulation, the elastic volumetric strain is now
used in the weak contribution, rather than the total volumetric strain.
• In the Layered Linear Elastic Material, the degree of freedom (DOF) for thetransverse strain is always active when a mixed formulation is used.
• In the Linear Elastic Material in the Shell interface in 2D axisymmetry, a
discontinuous Lagrange shape function is now used to represent the transverse
strain DOF.

New and Updated Models in Version 6.1
NONLINEAR HARMONIC RESPONSE

This tutorial model shows how to evaluate the harmonic response of a structure witha moderately nonlinear behavior. A nonlinear problem can only be solved using timedomain analysis. A way to speed up the computation is to use a linearized frequency
response analysis to provide good initial conditions.

150 |CHAPTER 1: RELEASE NOTESBRACKET — REDUCED-ORDER MODELINGThis tutorial model illustrates how to use a reduced-order model to compute theresponse of a structure subjected to three simultaneous loads that have independent
time histories. Reduced-order models provide an efficient way to analyze problems
within linear structural dynamics.
SELF-CONTACT OF A LOADED SPRING

This example shows how to set up self-contact for a coil spring. As the spring iscompressed by a vertical force applied to one of its ends, it comes into contact withitself and starts to rotate.
TORSION OF AN ISOTROPIC COSSERAT ELASTIC CYLINDER

This example demonstrates how to extend the built-in linear elastic material model toa Cosserat material through the addition of microrotation degrees of freedom. A
cylindrical bar under pure torsion is analyzed, and the effect of the Cosserat lengthscale parameter on the response is studied.
MICROMECHANICAL MODEL OF A PARTICULATE COMPOSITEIn this example, the homogenized elastic and viscoelastic properties of a particulatecomposite are computed based on the individual properties of elastic particles
embedded in a viscoelastic matrix.
Periodic boundary conditions are applied to a unit cell of the particulate composite
using the Cell Periodicity feature in the Structural Mechanics Module.
The transient viscoelastic response of the composite is used to determine thehomogenized material parameters using curve fitting optimization.
LINEAR BUCKLING ANALYSIS OF A TRUSS TOWER WITH DEAD LOADSThis example shows how to compute the critical buckling load in the presence of deadloads. A truss tower is supported by pretensioned guys. The pretension load andgravity on the truss are considered dead loads, while the vertical load applied at the topof the tower is considered the live load. The guys are modeled using the Wire interface.
VIBRATING STRING

This model has been updated so that the new Wire interface is used instead of the Truss
interface.

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HANGING CABLE

This model has been updated so that the new Wire interface is used instead of the Truss
interface.
HEATING CIRCUITThis model has been updated so that a Thin Layer in the Solid Mechanics interface isused to model the circuit, rather than a separate Membrane interface.

152 |CHAPTER 1: RELEASE NOTES

Subsurface Flow Module
New Functionality in Version 6.1
CLIMATE DATA: ASHRAE 2021

ASHRAE Weather Data 2021 has been integrated into COMSOL Multiphysics.
ASHRAE 2021 contains additional locations; there are more than 8500 stations in the2021 edition. You can select any of them in the Ambient Properties node. The databaseprovides typical climate data for the temperature, humidity, precipitation, and solar
radiation.
IMPROVED HANDLING OF FRACTURESIn the Darcy’s Law and Fracture Flow interfaces, the following improvements areavailable:• Fractures are now defined using phase-specific properties in the Fracture node. The
Fluid subnode describes the fluid properties, and the Fracture Material subnodeaccounts for the fracture properties, such as porosity or transmissivity.
• It is now possible to model Darcian or non-Darcian flow in fractures.
• The fractures can be highly conductive, like open channels, or can be represented
by thin barriers.
• Fractures now also support the ideal gas and the linearized storage model.
FRACTURES FOR TRANSPORT OF DILUTED SPECIESA new Fracture node is now available in the Transport of Diluted Species in PorousMedia and Transport of Diluted Species in Fractures interfaces. The new node isconsistent with other fracture nodes for porous media transport, and it includes two
subnodes, Fluid and Fracture Material. The Fluid subnode describes the fluid, velocity,and diffusion properties, and the Fracture Material subnode accounts for the fracture
properties.
STORAGE MODEL FOR UNSATURATED POROUS MEDIA

A new option for the Storage model setting in the Unsaturated Porous Medium node isadded. Now, it is possible to define the storage as a function of liquid content.

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USER-DEFINED PHASE TRANSITION

A User defined phase transition function in the Phase Change Material subnode is now
available for the Heat Transfer in Porous Media interface. This option enables you to
use an accurate phase change description from measured data.
THIN BARRIER MULTIPHYSICS COUPLING

The new Thin Barrier node for the Multiphase Flow in Porous Media multiphysics
interface makes it possible to add thin layers that act as a resistance for the flow fieldsof all phases without meshing through the layer’s thickness.
NEW PREDEFINED PLOTS

With the introduction of the new Add Predefined Plots feature, the number of default
plots that are produced has been reduced. Several plots that were default plots are now
instead optional, and can be added from the Add Predefined Plots window. There arealso several new useful predefined plots.

New Models in Version 6.1
PHASE CHANGE IN A SEMI-INFINITE SOIL COLUMN — LUNARDINISOLUTION

In this example, a heat-conduction problem with phase change in a porous material issolved, and the results are compared with the analytical solution, also known as the
Lunardini solution. This is the first test case from the InterFrost project.
CO2 STORAGE IN A GEOLOGIC FORMATIONThis example simulates the underground storage of CO2 in a part of the Johansen
Formation off the coast of Norway. The CO2 was injected using an injection well at a
rate of 15 kg/s over a period of 25 years, after which the well was closed. The modelis used to compute the spreading of CO2 over the simulation domain during theinjection phase and during the 25 years directly following the shutdown of theinjection well.
The model uses the new Reinterpolate interpolation data on computational meshfunctionality for Interpolation functions, leading to a significant reduction of thecomputation time when evaluating porosity and permeability over large geometries.

154 |CHAPTER 1: RELEASE NOTESUncertainty Quantification Module
New Functionality in Version 6.1
INVERSE UNCERTAINTY QUANTIFICATION STUDY TYPE

The Inverse Uncertainty Quantification study propagates information of experimental
data backward to gain more information on the calibration parameters. It computes
the posterior distribution of the calibration parameters that best reflects theirdistribution based on the experimental data and the prior knowledge of the calibration
parameters. The Markov chain Monte Carlo (MCMC) method is used to produce
samples from the posterior distribution of the calibration parameters.
MORE INPUT PARAMETER DATA GENERATE SCHEMES

Settings for input parameters, surrogate-based Monte Carlo analysis parameters, andsurrogate model verification parameters now support using data columns from results
tables as the data source. They also support combining specified value and data
columns with analytic probability distributions as the data source. The settings forsurrogate-based Monte Carlo analysis parameters support using nominal values as thedata source.

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Wave Optics Module
New Functionality in Version 6.1
DIELECTRIC SCATTERING WITH THE ELECTROMAGNETIC WAVES,
BOUNDARY ELEMENTS INTERFACE

It is now possible, in the Scattered field Formulation for the Electromagnetic Waves,
Boundary Elements interface, to solve problems involving multiple dielectric scatterers
embedded in an infinite domain.
WEAK FORMULATION PORT OPTION

When expanding the electric field on a port boundary, the new weak port formulation
adds a scalar dependent variable for the expansion coefficient (the S-parameter) andthen solves for the S-parameters and the tangential electric field on the boundary using
only a weak expression. Since no constraints are used, this formulation completely
removes the constraint elimination step when solving.
This new port formulation replaces the other constraint-free port formulation that was
introduced in version 6.0.
LAYERED IMPEDANCE BOUNDARY CONDITION

The Layered Impedance Boundary Condition is an extension of the Impedance Boundary
Condition that makes it possible to model a sequence of geometrically thin layers on topof a substrate. It is used on exterior boundaries where the field is known to penetrate
only a short distance outside the boundary. In brief, this feature combines a Layered
Transition Boundary Condition with an Impedance Boundary Condition.
This new feature is available for the Electromagnetic Waves, Frequency Domaininterface.
LAYERED TRANSITION BOUNDARY CONDITION

The Layered Transition Boundary Condition node that was added in version 6.0 to theElectromagnetic Waves, Frequency Domain interface has now also been added to theElectromagnetic Waves, Beam Envelopes interface.
The Layered Transition Boundary Condition node has also been updated to include allmaterial models that are available for the Transition Boundary Condition node, whichsimplifies the definition of material parameters for the boundary condition.

156 |CHAPTER 1: RELEASE NOTESLINEARLY POLARIZED PLANE WAVE BACKGROUND FIELD IN 2D
AXISYMMETRY

For 2D axisymmetry, there is a new background field, the Linearly Polarized Plane Wave
type. Here, the plane wave is expanded into a series of Bessel functions. Thisfunctionality makes it possible to very efficiently model the scattering of plane waves
from rotationally symmetric objects.
FEM–BEM MULTIPHYSICS COUPLING

To simplify the setup of models using both the Electromagnetic Waves, Frequency
Domain and Electromagnetic Waves, Boundary Elements interfaces, theElectromagnetic Waves, FEM–BEM multiphysics interface can be selected in the
Model Wizard.
This multiphysics interface adds the two physics interfaces and the Electric Field
Coupling multiphysics coupling feature to the new model.
SYMMETRY PLANE

The Symmetry Plane feature simplifies the definition of perfect electric conductor(PEC) and perfect magnetic conductor (PMC) symmetry planes. This feature is usedinstead of the Perfect Electric Conductor and Perfect Magnetic Conductor boundary
conditions when reducing the model size from symmetry considerations.
Furthermore, the information about the type and location of the Symmetry Plane
features are used when calculating far fields and when defining analytical Port mode
fields.
COVARIANT FORMULATION IN 2D AXISYMMETRY

In the 2D axisymmetric formulation, it is beneficial to formulate the out-of-planedependent variable as = rE  ,referred to as the covariant formulation. Here,  is the dependent variable, and theout-of-plane electric field component is calculated asE =   r .
The covariant formulation now has better performance in terms of numerical stability
and accuracy. In contrast with previous versions, eigenfrequency simulations can now
return a different number of eigenfrequencies. However, the returned solutions havebetter accuracy, and there are many fewer spurious solutions.

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This formulation is used for all study types, except Mode Analysis and Boundary Mode
Analysis.
SKIN DEPTH CALCULATORThe Skin Depth Calculator feature can be used to compute skin depth before performing
a full model computation. This functionality is useful when setting up the physics andboundary conditions.
The calculator is available in the Impedance Boundary Condition, Transition Boundary
Condition, Layered Impedance Boundary Condition and Layered Transition Boundary
Condition features.
PLOTTING OF ANALYTIC PORT MODE FIELDS BEFORE COMPUTATIONFor Rectangular, Circular, and Coaxial Port types, it is now possible to plot and inspect
the mode field before computing the full solution. This is useful for correctly defining
the other boundary conditions used in the model.
NO INCIDENT FIELD OPTION FOR SCATTERING AND MATCHED
BOUNDARY CONDITIONS

For the Scattering Boundary Condition and the Matched Boundary Condition for theElectromagnetic Waves, Beam Envelopes interface, there is now a new default option
for the Incident field parameter — the No incident field value. This option represents thecase when there are only outgoing waves at the particular boundary.
UPWIND FLUX OPTION FOR THE ELECTROMAGNETIC WAVES, TIMEEXPLICIT INTERFACEThe Flux type parameter in the Wave Equations node for the Electromagnetic Waves,
Time Explicit interface now also includes an Upwind flux value. This option cansometimes be useful to improve S-parameter calculations that could have low accuracy
due to overdissipation around perfect electric conductor (PEC) edges, when using thedefault Lax-Friedrichs flux parameters.
PERIODIC PORT REFERENCE POINT

The Periodic Port Reference Point subnode has been simplified to only allow theselection of a single reference point.
NEW DEFAULT COLOR TABLE WHEN ADDING PLOTS

When adding a new 2D or 3D plot, the created plot will use the RainbowLight color
table by default.

158 |CHAPTER 1: RELEASE NOTESNew and Updated Models in Version 6.1
CLOAKING OF A CYLINDRICAL SCATTERER WITH GRAPHENE

In this model, a cloaking method is introduced using an electrically tuned monolayerof graphene. The model shows that when a cylindrical dielectric scatterer is covered ingraphene, the scattering cross section is greatly reduced at the designated frequency,
making it electromagnetically invisible. This model aims to demonstrate the use of the
Background wave type option Linearly polarized plane wave in a 2D axisymmetric model.
OPTICAL YAGI–UDA ANTENNAThis model demonstrates the use of the Electromagnetic Waves, Boundary Elementsinterface to model dielectric scattering from an optical Yagi–Uda antenna. The antenna
is driven by an electrical point dipole, which is implemented through the backgroundfield. The field distribution around the antenna and the far-field radiation pattern areevaluated, showing high directivity.
OPTICAL RING RESONATOR NOTCH FILTER 3D

This model calculates the spectral properties of a 3D optical ring resonator. The model
demonstrates how to use parts from the Wave Optics Part Library and how to set up
the Field Continuity boundary condition at boundaries, where there is a jump in thepredefined phase approximation.
GRAPHENE METAMATERIAL PERFECT ABSORBER

Graphene, carbon atoms arranged in a two-dimensional hexagonal lattice, has sparked
tremendous research and application interests since its experimental discovery about
two decades ago. Besides being ultrathin, this material exhibits a plethora of interesting
properties, including high electrical and thermal conductivities, high elasticity, highmechanical strength, and so on. Among various applications, a promising field isgraphene-based electro-optical devices, such as photodetectors, photodiodes, andmetamaterials. An additional desirable trait of graphene is that its optical response canbe actively controlled by changing its Fermi energy via electrical gating. This model
first demonstrates how to compute the optical conductivity of graphene using the
Kubo formula. The computed conductivity is then used to model a graphene-based
THz metamaterial absorber.
ENHANCED COATING FOR A MICROELECTROMECHANICAL MIRROR

This example demonstrates how to optimize the thickness of a microelectromechanical(MEMS) mirror coating material for maximum reflectivity. To reduce the simulation

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time, a Layered Impedance Boundary Condition is used to model the thin coating
material on top of the metallic mirror.
TAPERED WAVEGUIDEA tapered optical waveguide structure is used for matching two waveguides that havedifferent geometric cross sections or different material parameters. The tapered
waveguide has one geometric cross section at the input plane and another cross section
at the output plane. In between these planes, the core width changes linearly with the
propagation distance.
This model demonstrates how to define a user-defined phase and wave vector for theElectromagnetic Waves, Beam Envelopes interface when used with perfectly matchedlayers (PMLs). The PMLs are used for absorbing the radiation that is not matching theport mode fields.
FRESNEL LENSThis model has been updated to use the new Spatial FFT dataset for performing a
Fourier transformation in the postprocessing.
OPTICALLY ANISOTROPIC WAVEGUIDEThis model has been updated to use a coordinate transformation when rotating theoptical axis to achieve longitudinal anisotropy.
OPTICAL SCATTERING OFF A GOLD NANOSPHERE

This model has been updated to use the new Symmetry Plane feature.
SELF-FOCUSINGThis model has been updated to use the new Symmetry Plane feature.
FABRY-PEROT RESONATOR

This model has been updated to use the new Symmetry Plane feature.

Backward Compatibility with Version 6.0 and Earlier
COVARIANT FORMULATION

In 2D axisymmetry, for all studies except Mode Analysis and Boundary Mode Analysis, thecovariant formulation is used (see Covariant Formulation in 2D Axisymmetry).
Thereby, Ephi is not a dependent variable. To get the correct out-of-plane electricfield component, the variable ewfd.Ephi should be used. Here, it is assumed that the160 |CHAPTER 1: RELEASE NOTESdependent variable has been given the name E and that the tag for the physics interface
is ewfd.
NEW DEFAULT VALUE FOR THE INCIDENT-FIELD PARAMETER

For the Scattering and Matched Boundary Condition features for the Electromagnetic
Waves, Beam Envelopes interface, when setting the Incident electric field amplitude
parameter E0i, using the Java API, the IncidentField parameter must also be set to
EField to make the electric field excitation effective. This is required as the newdefault value for the IncidentField parameter is NoIncidentField.
NEW DEFAULT VALUE FOR THE RELATIVE PERMITTIVITY, HIGHFREQUENCY PARAMETER

The default value for the Relative permittivity, high frequency parameter, epsilonInf,
has changed from From material to User defined.

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Material Library
New and Updated Material Data in Version 6.1
In version 6.1, the Material Library contains 12,763 materials and 107,005 material
property datasets. The following improvements and additions have been made:• Added data for: Nitronic 32, Nitronic 33, several tool steels, Cu-based alloys,
commercial purity Ti, 4340, Inconel 600, 304, 304L, 314, 316, 316 H, 316 Ti,
416, 446, 15-5 PH, and several Hastelloys.
• Added data for several ECTFE, polypropylenes, PPS and PPE/PP, PPE/PS, and
PPO/PP polymers blends.
• Added data for LiCoO2, Li22Si5, Li13Si4, Li7Si3, and Li12Si7.
• Added data for the following polymers: polycarbonates, polyamides, PPE, ULTEM,
Xenoy, NORYL, Amodel, Meldin, Torlon, Ixef, PEEK, and KetaSpire.
• Added data for: Haynes 282, 20Cb-3, K63017, 21Cr-6Ni-9Mn, 420, 431, 201,13-8 Mo PH, MP35N, BioDur 108, Custom 450, Custom 455, Temperaturecompensator 32 (type 1), Chrome core 8-FM, Chrome core 8-XP, Hiperco 27 alloy,
Hiperco 50A alloy, Hiperco 50 alloy, Hiperco 50 HS alloy, Hiperco 15 alloy, andManganin alloy 13.
• Added data for LiSi.
• Added data for several engineering plastics.
• Several epoxies and silicones have been added.
• Several tool steels and Fe-Cr alloys have been added.
• Added several circuit boards and antenna substrates.
• Some diallyl (ortho-, iso-) phthalates (DAP & DAIP) have been added.
• Data has been added for: Inconel 702, Nimonic 901, 15Cr15Ni1MoTi, liquid H
and He, and some Mylars.
• Added data for PCBs from Rogers and TACONIC.
• Added properties for several Corning, Schott, Ohara, Incoloy 865, and
FORMGLAS glasses.
• Added creep data for: S20910, AM-355, 15-7 Mo PH, 201LN, 422, Ti-140A, C130AM, HM21 and HK31.

162 |CHAPTER 1: RELEASE NOTES• Added strength data for: 304, 316, 316LN, Ti-155A, 52100, 440C, T1, T5, M1,
M2, M10, Al 1000, Al 2024, Al 6013, 1010 steel, 201L, 2304, 403 and 403Nb.
• Added stress-strain and SN data for Ti Grade 4.
• Additional data has been added for the thermal expansion for several tool steels. In
most cases, the data changed by less than 3%. The following had changes of 5% to
10% near 20 °C and less at higher temperatures: D2, H12, M4, and O1.
• A new reference is used for the elastic modulus of M2. The new values are similar at
20 °C but are 30% higher at 600°C.
• Added new references for H11 and H11 mod tool steels. For H11, the thermal datachanged by up to 10% from previous values. For H11 mod the elastic properties
changed by up to 5%, mainly at elevated temperatures.
• The data for the UTS, YS, and % elongation for stainless steels 420 and 440C wereincorrect. This data was removed from the database. New yield strength data for
420 has been added.
• The electrical resistivities for Pyrex, Vycor, and window glass were too high by afactor of 100. It has been corrected.
• The specific heat and heat capacity for the following materials were extended down
to the 10 K to 50 K range: Al 7075, Inconel X-750, BeO, Cr2O3, CuO, Cu2O,
Fe2O3, Fe3O4, MnO, MnO2, Mn2O3, NiO, NbO2, Nb2O3, SiO2 (cristobalite),
SiO2 (tridymite), SnO, SnO2, TiO2 (anatase), TiO2 (rutile), and ZnO. The room
temperature values changed by 5% or less due to the new data.
• The stress-based fatigue data for the following four materials was in error: API-X100
pipeline steel, ATI 332Mo, ATI 334Mo, AZ31B-H24. The number of reversals wasused instead of the number of cycles, and the cycles in the database were too highby a factor of 2. They have been corrected.
• The strain-based fatigue data for the following 14 materials was in error: 617, P92,
GH413, API-X100, 34CrNiMo6, AF1410, SAE J435 Grade 0050A, Alloy 709(NF 709), Ductile Ni-Resist D-5S, SAE J435 Grade 0030, 8630, 4140, and Inconel
617 (weld). The number of reversals was used instead of the number of cycles, andthe cycles in the database were too high by a factor of 2. They have been corrected.
• The thermal conductivity for Schott Borofloat 33 was too high by a factor of
approximately 20. It has been corrected.
• Added additional references for the electrical resistivity for Al and 310S stainless.
The values changed by 5% or less due to the new data.

MATERIAL LIBRARY|163

• Added additional references for the specific heat and heat capacity for: Al, Ti, Sn,
Pb, and Constantan. The room temperature values changed by 5% or less due to thenew data.
• The relative permittivity of sapphire was incorrect and has been fixed.
• The elastic modulus of 7049 Al was incorrect and has been fixed.
• Replaced the data for the thermal conductivity for Cu-based alloys C24000 and
C51100 with a new reference. The values changed by up to 10% and 25%,
respectively.
• Replaced the data for the thermal expansion for cobalt with a new reference. The
values changed by up to 20%.
• The data for the thermal expansion for S20103, S20153, and S21800 has been
replaced. The original reference had the materials mislabeled.
• The heat capacity and specific heat data for Li22Si5, Li13Si4, Li7Si3, and Li12Si7
were incorrect. The labeling in the reference was incorrect, and the data given in thereference was normalized to the number of atoms in a molecule. These have been
fixed.

164 |CHAPTER 1: RELEASE NOTESLiveLink™ for Excel ®
New Functionality in Version 6.1
The libraries for reading and writing Excel files have been updated.

LIVELINK™ FOR EXCEL®

|

165

LiveLink™ for MATLAB ®
New Functionality in Version 6.1
SYSTEM REQUIREMENTS
LiveLink™ for MATLAB® is now again supported on all platforms, including macOS on

Apple silicon processors like M1. MacOS is still supported on computers running on
x64 chips, similar to the support for Linux® and Windows®.
NEW FUNCTIONS FOR DATASETS

The mphdataset and mphdatasetinfo functions are new functions for plotting
datasets and accessing information about datasets. These functions are very usefulwhen working with datasets that are driven using changing parameters or with models
that have varying geometries.
NEW FUNCTIONS FOR MODELS STORED IN MODEL MANAGER

The following new functions are introduced for working with models that are stored
in databases using Model Manager:• The mmmodelinfo function returns information about such models and can
additionally be used to get information about models that are stored in an MPHfile.
• The mmsave function is used to store model as drafts or regular models.
• The mmgetbranch function can be used to obtain a batch variable that is used whensaving a model in Model Manager that has not been previous stored in ModelManager.
Other functions such as mphtags, mphopen, and mphnavigator have been updated tosupport models loaded from Model Manager.
OTHER IMPROVEMENTS• The mphrun function makes it possible to call the run() method on model nodes
that support it and that support showing the progress bar window while solving. To
do so, use the new argument 'run'. It is set to on by default, but you can turn it
off in the rare event that you want to avoid recreating plot data even when theunderlying model data or plot settings have changed. In most cases, users would
want to leave this setting on.

166 |CHAPTER 1: RELEASE NOTES• The mphsave function is used to save a model as an MPH-file or as source file in theJava®, MATLAB®, or VBA file formats. It now has support for setting the title andthumbnail directly when saving a model.
• It is now possible to open a COMSOL® model directly from the Current Folder
browser in MATLAB®. Just right-click the COMSOL® MPH-file and select Open;the model will then be loaded into the MATLAB® workspace in the same way as
when using mphopen. If you want to open a model in the COMSOL® user interface,instead right-click the MPH-file and select Open Outside MATLAB.

Backward Compatibility with Version 6.0
The mphint and mphgetp functions that have been deprecated for some time havebeen removed.
All functions that were named after the names of color tables (prism, heat, spectrum,and so on) that have been deprecated for some time have been removed. Use themphcolortable function instead to get information and data about color tables thatare distributed with the COMSOL Multiphysics software, stored on disk, or
embedded inside models. The colortable function is deprecated but can still be used.

Backward Compatibility with Version 5.6
COLOR TABLES

All functions that have to do with color tables (for example, cividis, cyclic, anddisco) except for colortable have been deprecated. When using the colortablefunction, you can use autocompletion to get a list of available color tables. As analternative to using, for example, cividis you can instead use
table = colortable('cividis');
REPLACED AND DEPRECATED FUNCTIONS

The mphint, mphgetp, and mphgetmodelnode functions are deprecated.
mphgetmodelnode has been replaced by mphcomponentinfo where new features havebeen added. The deprecated functions still exist but will result in a warning when used,
and they may be removed in a future release of COMSOL Multiphysics. Such warnings
can be disabled using this command
warning('off','COMSOL:DEPRECATED')LIVELINK™ FOR MATLAB®

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167

LiveLink™ for Simulink ®
New Functionality in Version 6.1• The COMSOL Cosimulation block has been rewritten with focus on performanceand stability. This means that simulation speed has improved substantially. It should
now be easier to get models to simulate well when doing cosimulation with less or
no manual adjustment of the solver settings or scaling of variables. Note that models
that do require manual scaling (for example, most structural mechanics models) will
also require manual scaling when doing cosimulation together with Simulink®.
• If a Simulink® diagram is using more than one COMSOL Cosimulation block, thenadditional hidden COMSOL Multiphysics® server processes are started that handle
the simulation of the additional blocks. This behavior may lead to a slightly longer
startup time but also leads to a faster simulation time overall.
• Outputs are defined using a global scalar expression. The expression now has toinclude the component scope where the variable is defined, even if the model
contains only one component (for example, comp1.point1). It is good practice tocreate a probe with the desired output expression.
• Unit handling has been updated so that units are shown for inputs, outputs, andblock parameters for values that do have units. It is the user’s responsibility to makesure that inputs and block parameters are set using the expected units. Outputs fromthe block are now converted into the unit that is shown for each output.

General Backward Compatibility
Models that have been built with earlier versions of COMSOL must be reexported
from COMSOL again. If simulations with old models are attempted, the following
error message will appear in the COMSOL Multiphysics server window as well as thefunctional mockup unit (FMU) log file that can be opened from Simulink: The
COMSOL Cosimulation Block and COMSOL Multiphysics server version mismatch.
Please reexport the cosimulation FMU-file from COMSOL Multiphysics.

168 |CHAPTER 1: RELEASE NOTESThe COMSOL API for Use with Java ®
COMSOL 6.1 API Changes
PERIODIC CONDITIONS — DESTINATION SELECTION

The Destination Selection subnode under Periodic Condition nodes has been removed inversion 6.1 and has been replaced by an optional Destination Selection section in the
Settings windows for Periodic Condition nodes. It can still be added from the API for
backward compatibility. The only difference in behavior for old API code when using
Destination Selections is what the entities of the feature’s selection are when it is set toall boundaries:
A periodic condition:
PhysicsFeature pc = model.physics("ec").feature("pc1");

Set the selection to all boundaries of the destination domains feature:pc.feature("dd1").selection().all();

The result of this statement typically differs between versions 6.0 and 6.1:
int[] entities = pc.feature("dd1").selection().entities();

In version 6.0, only the automatic destination entities from the parent’s automatic
destination selection were returned. Now, the software returns all entities that overlap
with the parent selections (source and destination). The interpretation of the allboundaries flag being set is still the same: making the periodic condition use theautomatic destination. The only difference is what the API returns for the selection of
the destination domains.
FILLETS AND CHAMFERS IN 2D GEOMETRIESIn new 2D models, when adding Fillet and Chamfer features, you typically do notneed to set the selectinsketch property, as it is set to on by default.
GEOMETRY EXPORTThe following method now sets the file format of the geometry export:
model.component(<ctag>).geom(<tag>).export().setType(<format>);where <format> can take the following values: nativeascii, nativebin,parasolidbin, parasolidascii, acisbin, acisascii, iges, step, stlbin,
stlascii, or dxf.

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To get the file format that is set for the geometry export, use:
String fileType = model.component(<ctag>).geom(<tag>).export().
getType();

COMSOL 6.0 API Changes
PAIR FEATURES

The removal of the fallback features under pair features can break API code that you
have written that accesses those features. The presence of a default pair feature may also
create a different configuration compared to what previous API runs did.
Java® or MATLAB® program that accessed fallback features under a pair feature will
not work anymore. This is a necessary limitation because any attempt to support such
API backward compatibility will be both unintuitive and unsafe. For most physics
created from the API, the default feature from the physics will act as the fallback to thepair features. As long as the default fallback feature in 5.6 was of the same type, thebehavior in 6.0 will be equivalent. If you used a special fallback feature for a pair featurein 5.6, you now place it either before or after the pair feature and use the same selection
as the pair feature. Placing the fallback feature afterward makes it possible to use thepair feature’s selection directly. The example below shows such code for 5.6 and how
the equivalent code in 6.0 can be written:// Creating a pair feature in both 5.6 and 6.0
model.component("comp1").physics("es").create("cont1","Continuity", 2);// Assign some pairs to the pair featuremodel.component("comp1").physics("es").feature("cont1").
set("pairs", new String[]{"ap1", "ap2"});// Creating a fallback feature under a pair in 5.6 (this will notwork in 6.0)
model.component("comp1").physics("es").feature("cont1").
create("sfcd1", "SurfaceChargeDensity", 2);// Accessing a settings in 5.6 (this will not work in 6.0)
model.component("comp1").physics("es").feature("cont1").
feature("sfcd1").set("rhoqs", "1e-9");// Creating an equivalent feature in 6.0 that act as fallback to
the pair featuremodel.component("comp1").physics("es").create("sfcd1","SurfaceChargeDensity", 2);// Use the same selection as the pair feature
int[] ent = model.component("comp1").physics("es").
feature("cont1").selection().entities();

170 |CHAPTER 1: RELEASE NOTES

model.component("comp1").physics("es").feature("sfcd1").
selection().set(ent);// Accessing a settings in 6.0
model.component("comp1").physics("es").feature("sfcd1").
set("rhoqs", "1e-9");

When a physics interface is created from the API in 6.0, it will also add default pairfeatures that did not exist in 5.6. As long as the final model uses all created pairs, thebehavior will be the same in 6.0; otherwise, it may be necessary to disconnect thedefault pair feature with an extra command. Below is an example for the Electric
Currents interface, but the actual set operation is identical for all interfaces.
model.component("comp1").physics("ec").feature("dcont1").
set("pairDisconnect", true);

COMSOL 5.6 API Changes
MESH PART UNITSThe unit of the mesh part created by createMeshPart is now set to the unit of thesource geometry. In earlier versions, it was created without a unit.
THE ADAPT FUNCTION — THE EXPRTYPE PROPERTY

For the adapt API function, the default for the exprtype property has changed: It iserror if added in a component and a solution exists; otherwise, it is size. In previous
versions, the default was always error.
This concludes the release notes for COMSOL Multiphysics version 6.1.

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171

172 |

CHAPTER 1: RELEASE NOTESI n d e x
A

AC/DC Module

new functionality in 76

new and updated models in 41

Electrodeposition Module

new functionality in 37
Acoustics Module

new functionality in 78
F

new functionality in 44

new functionality in 80

Application Builder, new functionality in

Fuel Cell & Electrolyzer Module

13
B

new and updated models in 84

backward compatibility, general considerations 32

new functionality in 81
G

Battery Design Module

new functionality in 85

new functionality in 53

geometry and mesh, new functionality

CAD Import Module
new functionality in 57

general new functionality 10
Geomechanics Module

new and updated models in 56

C

Fatigue Modulefor 21H

CFD Module

Heat Transfer Module
backward compatibility 90–92, 104, 129

new functionality in 60

new applications in 89

new models in 62

new functionality in 86

Chemical Reaction Engineering Module
new functionality in 64

L

new functionality in 94

Composite Materials Module

LiveLink for Excel

new functionality in 70

new functionality in 165

new models in 71

LiveLink for MATLABCOMSOL API changes 169

backward compatibility 167

COMSOL Compiler

new functionality in 165–166

new functionality in 17

LiveLink for Simulink

COMSOL Multiphysics, new functionality in 17

new functionality in 168

Corrosion Module

LiveLink™ products for CAD
new functionality in 57

new and updated models in 74
new functionality in 72
D

Liquid & Gas Properties Module

Design Module
new functionality in 57

M

Material Library
new and updated material data in 162
new material data in 162
MEMS Module

E

ECAD Import Module
new functionality in 75

new functionality in 95
new models in 99

Electrochemistry Module

I N D E X | 173backward compatibility 132

Metal Processing Module

new applications in 131

new functionality in 101
new models in 102

new functionality in 130

Microfluidics Module

results and visualization, new functionali-

new functionality in 103

ty in 27

updated applications in 103

RF Module

Molecular Flow Module

new and updated apps and models inbackward compatibility 105

136

new functionality in 105

new functionality in 133

Multibody Dynamics Module

Rotordynamics Module

new functionality in 106
N

new functionality in 139
new models in 140

Nonlinear Structural Materials Module
new functionality in 109

S

new models in 111
O

new functionality in 141
new models in 150

operators, functions, and definitions,studies and solvers, new functionality in

new and updated 25

26

Optimization Module

Subsurface Flow Module

backward compatibility 115

new functionality in 153

new functionality in 113

new models in 154

new models in 114
P

Particle Tracing Module
backward compatibility 118
new applications in 105, 117
new functionality in 116
Pipe Flow Module
new functionality in 119
new models in 119
Plasma Module
backward compatibility 124
new applications in 123
new functionality in 121
Polymer Flow Module
new functionality in 128
new models in 129
Porous Media Flow Module
new functionality in 125

R

174 | I N D E X

Ray Optics Module

Structural Mechanics Module

U

Uncertainty Quantification Module
new functionality in 155

W Wave Optics Module

new functionality in 156
new models in 159