COMSOL Multiphysics
Release Notes

COMSOL Multiphysics Release Notes© 1998–2019 COMSOL
Protected by patents listed on www.comsol.com/patents, and U.S. Patents 7,519,518; 7,596,474;
7,623,991; 8,219,373; 8,457,932; 8,954,302; 9,098,106; 9,146,652; 9,323,503; 9,372,673; 9,454,625;
and 10,019,544. Patents pending.
This Documentation and the Programs described herein are furnished under the COMSOL Software License
Agreement (www.comsol.com/comsol-license-agreement) and may be used or copied only under the termsof the license agreement.
Support for implementation of the ODB++ Format was provided by Mentor Graphics Corporation pursuant
to the ODB++ Solutions Development Partnership General Terms and Conditions. ODB++ is a trademark
of Mentor Graphics Corporation.
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 5.5

Contact Information
Visit the Contact COMSOL page at www.comsol.com/contact to submit generalinquiries, contact Technical Support, or search for an address and phone number. You canalso visit the Worldwide Sales Offices page at www.comsol.com/contact/offices foraddress and contact information.
If you need to contact Support, an online request form is located at the COMSOL Accesspage at www.comsol.com/support/case. Other useful links include:• Support Center: www.comsol.com/support• Product Download: www.comsol.com/product-download• Product Updates: www.comsol.com/support/updates• COMSOL Blog: www.comsol.com/blogs• Discussion Forum: www.comsol.com/community• Events: www.comsol.com/events• COMSOL Video Gallery: www.comsol.com/video• Support Knowledge Base: www.comsol.com/support/knowledgebase
Part number: CM010001

C o n t e n t s
Chapter 1: Release Notes
New Products

12

Metal Processing Module . . . . . . . . . . . . . . . . . . . . 12
Porous Media Flow Module . . . . . . . . . . . . . . . . . . . 12
COMSOL Multiphysics

13

General New Functionality . . . . . . . . . . . . . . . . . . . 13
New Functionality in the Application Builder . . . . . . . . . . . . 13
New Functionality in COMSOL Compiler™ . . . . . . . . . . . . 16
New Functionality in COMSOL Server™

. . . . . . . . . . . . . 17

New and Improved General Functionality in COMSOL Multiphysics . . . 17
New Functionality in the Physics Interfaces . . . . . . . . . . . . . 20
New Geometry and Mesh Functionality . . . . . . . . . . . . . . 20
New and Updated Operators, Functions, and Definitions . . . . . . . 23
New Functionality in Studies and Solvers . . . . . . . . . . . . . . 25
New and Improved Results and Visualization Functionality . . . . . . . 28®
New Java API Methods . . . . . . . . . . . . . . . . . . . . 32
General Backward Compatibility Considerations . . . . . . . . . . . 33
Backward Compatibility with Version 5.4. . . . . . . . . . . . . . 33
Backward Compatibility with Version 5.3a . . . . . . . . . . . . . 34
Backward Compatibility with Version 5.3. . . . . . . . . . . . . . 35
Backward Compatibility with Version 5.2a . . . . . . . . . . . . . 36
Backward Compatibility with Version 5.2. . . . . . . . . . . . . . 38
Backward Compatibility with Version 5.1. . . . . . . . . . . . . . 38
Backward Compatibility with Version 5.0. . . . . . . . . . . . . . 39
AC/DC Module

41

New Functionality in Version 5.5 . . . . . . . . . . . . . . . . . 41
Backward Compatibility with Version 5.4 and Earlier . . . . . . . . . 46
Backward Compatibility with Version 5.2 and Earlier . . . . . . . . . 46
Backward Compatibility with Version 5.0 and Earlier . . . . . . . . . 47

CONTENTS | 3

Acoustics Module

49

New Functionality in Version 5.5 . . . . . . . . . . . . . . . . . 49
New and Updated Model Examples in 5.5 . . . . . . . . . . . . . 55
Backward Compatibility with Version 5.4. . . . . . . . . . . . . . 57
Backward Compatibility with Version 5.3a . . . . . . . . . . . . . 57
Backward Compatibility with Version 5.3. . . . . . . . . . . . . . 57
Backward Compatibility with Version 5.2. . . . . . . . . . . . . . 57
Backward Compatibility with Version 5.1. . . . . . . . . . . . . . 57
Batteries & Fuel Cells Module

59

New Functionality in Version 5.5 . . . . . . . . . . . . . . . . . 59
New and Updated Applications and Models in Version 5.5 . . . . . . . 61
Backward Compatibility with Version 5.4. . . . . . . . . . . . . . 62
CAD Import Module, Design Module, and LiveLink™ Products
for CAD63

New Functionality in Version 5.5 . . . . . . . . . . . . . . . . . 63
New Functionality in the Design Module in Version 5.5 . . . . . . . . 63
New Functionality in LiveLink™ for AutoCAD® in Version 5.5 . . . . . 64
New Functionality in LiveLink™ for Inventor® in Version 5.5 . . . . . . 64
New Functionality in LiveLink™ for PTC® Creo® Parametric™ in
Version 5.5. . . . . . . . . . . . . . . . . . . . . . . . 64
New Functionality in LiveLink™ for Revit® in Version 5.5 . . . . . . . 64®
LiveLink™ for Solid Edge . . . . . . . . . . . . . . . . . . . 65®
LiveLink™ for SOLIDWORKS . . . . . . . . . . . . . . . . . 65
Backward Compatibility with Previous Versions . . . . . . . . . . . 66
CFD Module

67

New Functionality in Version 5.5 . . . . . . . . . . . . . . . . . 67
New Model in Version 5.5. . . . . . . . . . . . . . . . . . . . 68
Backward Compatibility with Version 5.4 and Earlier . . . . . . . . . 68
Backward Compatibility with Version 5.3a . . . . . . . . . . . . . 69
Backward Compatibility with Version 5.0. . . . . . . . . . . . . . 70
Chemical Reaction Engineering Module

71

New Functionality in Version 5.5 . . . . . . . . . . . . . . . . . 71
Backward Compatibility with Version 5.4 and Earlier . . . . . . . . . 72
Backward Compatibility with Version 5.3a and Earlier . . . . . . . . . 73

4 | CONTENTS

Backward Compatibility with Version 5.0 and Earlier . . . . . . . . . 73
Composite Materials Module

77

New Functionality in Version 5.5 . . . . . . . . . . . . . . . . . 77
New Models in Version 5.5 . . . . . . . . . . . . . . . . . . . 82
Corrosion Module

84

New Functionality in Version 5.5 . . . . . . . . . . . . . . . . . 84
New and Updated Models in Version 5.5. . . . . . . . . . . . . . 85
Backward Compatibility with 5.4 . . . . . . . . . . . . . . . . . 86
ECAD Import Module

87

New Functionality in Version 5.5 . . . . . . . . . . . . . . . . . 87
Backward Compatibility with Version 5.3a . . . . . . . . . . . . . 87
Backward Compatibility with Version 5.2a . . . . . . . . . . . . . 87
Backward Compatibility with Version 5.0. . . . . . . . . . . . . . 87
Electrochemistry Module

88

New Functionality in Version 5.5 . . . . . . . . . . . . . . . . . 88
New and Updated Models in Version 5.5. . . . . . . . . . . . . . 89
Backward Compatibility with Version 5.4. . . . . . . . . . . . . . 89
Electrodeposition Module

91

New Functionality in Version 5.5 . . . . . . . . . . . . . . . . . 91
New and Updated Models in Version 5.5. . . . . . . . . . . . . . 92
Backward Compatibility with Version 5.4. . . . . . . . . . . . . . 93
Fatigue Module

94

New Functionality in Version 5.5 . . . . . . . . . . . . . . . . . 94
Backward Compatibility with Version 5.3. . . . . . . . . . . . . . 94
Geomechanics Module

95

New Functionality in Version 5.5 . . . . . . . . . . . . . . . . . 95
New Models in Version 5.5 . . . . . . . . . . . . . . . . . . . 95
Heat Transfer Module

97

New and Improved Functionality in Version 5.5 . . . . . . . . . . . 97
New Applications in Version 5.5 . . . . . . . . . . . . . . . .

102

CONTENTS | 5

6 | CONTENTS

Updated Applications in Version 5.5 . . . . . . . . . . . . . .

104

Backward Compatibility with Version 5.4. . . . . . . . . . . . .

105

Backward Compatibility with Version 5.3a . . . . . . . . . . . .

106

Backward Compatibility with Version 5.3. . . . . . . . . . . . .

108

Backward Compatibility with Version 5.2a . . . . . . . . . . . .

109

Backward Compatibility with Version 5.2. . . . . . . . . . . . .

110

Backward Compatibility with Version 5.1. . . . . . . . . . . . .

111

Backward Compatibility with Version 5.0. . . . . . . . . . . . .

111

Obsolete Features . . . . . . . . . . . . . . . . . . . . .

114

MEMS Module

115

New Functionality in Version 5.5 . . . . . . . . . . . . . . . .

115

New Models in Version 5.5 . . . . . . . . . . . . . . . . . .

120

Backward Compatibility with Version 5.2. . . . . . . . . . . . .

121

Microfluidics Module

122

New Models in Version 5.5 . . . . . . . . . . . . . . . . . .

122

Backward Compatibility with Version 5.3a . . . . . . . . . . . .

122

Mixer Module

123

New Functionality in Version 5.5 . . . . . . . . . . . . . . . .

123

Molecular Flow Module

124

Backward Compatibility with Version 5.0 and Earlier . . . . . . . .

124

Multibody Dynamics Module

125

New Functionality in Version 5.5 . . . . . . . . . . . . . . . .

125

New Models in Version 5.5 . . . . . . . . . . . . . . . . . .

128

Nonlinear Structural Materials Module

130

New Functionality in Version 5.5 . . . . . . . . . . . . . . . .

130

New Models in Version 5.5 . . . . . . . . . . . . . . . . . .

132

Optimization Module

133

New Functionality in Version 5.5 . . . . . . . . . . . . . . . .

133

New and Updated Models in Version 5.5. . . . . . . . . . . . .

134

Backward Compatibility with Version 5.4. . . . . . . . . . . . .

135

Particle Tracing Module

136

New Functionality in Version 5.5 . . . . . . . . . . . . . . . .

136

Important Fixes in Version 5.5 . . . . . . . . . . . . . . . . .

137

Backward Compatibility with Version 5.4. . . . . . . . . . . . .

139

Backward Compatibility with Version 5.3 and Earlier . . . . . . . .

139

Backward Compatibility with Version 5.2a and Earlier . . . . . . . .

140

Backward Compatibility with Version 5.2. . . . . . . . . . . . .

141

Backward Compatibility with Version 5.1. . . . . . . . . . . . .

141

Backward Compatibility with Version 5.0 and Earlier . . . . . . . .

142

Pipe Flow Module

143

New Functionality in Version 5.5 . . . . . . . . . . . . . . . .

143

New Models and Updated Models in Version 5.5. . . . . . . . . .

144

Backward Compatibility with Version 5.3. . . . . . . . . . . . .

144

Backward Compatibility with Version 5.1 and Earlier . . . . . . . .

144

Plasma Module

145

New Functionality in Version 5.5 . . . . . . . . . . . . . . . .

145

New and Updated Applications and Models in Version 5.5 . . . . . .

145

Backward Compatibility with Version 5.3a and Earlier . . . . . . . .

145

Backward Compatibility with Version 5.3 and Earlier . . . . . . . .

146

Backward Compatibility with Version 5.2 and Earlier . . . . . . . .

147

Backward Compatibility with Version 5.1. . . . . . . . . . . . .

147

Ray Optics Module

148

New Functionality in Version 5.5 . . . . . . . . . . . . . . . .

148

New Applications in Version 5.5 . . . . . . . . . . . . . . . .

150

Important Fixes in Version 5.5 . . . . . . . . . . . . . . . . .

152

Backward Compatibility with Version 5.4. . . . . . . . . . . . .

153

Backward Compatibility with Version 5.3 and Earlier . . . . . . . .

153

Backward Compatibility with Version 5.2a and Earlier . . . . . . . .

154

Backward Compatibility with Version 5.2. . . . . . . . . . . . .

155

Backward Compatibility with Version 5.0. . . . . . . . . . . . .

156

RF Module

158

New Functionality in Version 5.5 . . . . . . . . . . . . . . . .

158

New and Models in Version 5.5 . . . . . . . . . . . . . . . .

160

CONTENTS | 7

Rotordynamics Module

161

New Functionality in Version 5.5 . . . . . . . . . . . . . . . .

161

New Models in Version 5.5 . . . . . . . . . . . . . . . . . .

163

Semiconductor Module

165

New Functionality in Version 5.5 . . . . . . . . . . . . . . . .

165

New Models in Version 5.5 . . . . . . . . . . . . . . . . . .

166

Structural Mechanics Module

168

New Functionality in Version 5.5 . . . . . . . . . . . . . . . .

168

New Models in Version 5.5 . . . . . . . . . . . . . . . . . .

178

Backward Compatibility with Version 5.2. . . . . . . . . . . . .

180

Subsurface Flow Module

181

New Functionality in Version 5.5 . . . . . . . . . . . . . . . .

181

New Models in Version 5.5 . . . . . . . . . . . . . . . . . .

182

Backward Compatibility with Version 5.4. . . . . . . . . . . . .

182

Backward Compatibility with Version 5.3a and Earlier . . . . . . . .

182

Wave Optics Module

184

New Functionality in Version 5.5 . . . . . . . . . . . . . . . .

184

New and Updated Models in Version 5.5. . . . . . . . . . . . .

186

Material Library188

New and Updated Material Data in Version 5.5 . . . . . . . . . .

188

LiveLink™ for MATLAB®

190

Backward Compatibility with Version 5.4. . . . . . . . . . . . .

191

Backward Compatibility with Version 5.2. . . . . . . . . . . . .

191

Backward Compatibility with Version 5.0. . . . . . . . . . . . .

191

The COMSOL API for Use with Java

8 | CONTENTS

190

New Functionality in Version 5.5 . . . . . . . . . . . . . . . .

®

192

COMSOL 5.4 API Changes . . . . . . . . . . . . . . . . . .

192

COMSOL 5.3a API Changes

193. . . . . . . . . . . . . . . . .

COMSOL 5.3 API Changes . . . . . . . . . . . . . . . . . .

193

COMSOL 5.2a API Changes. . . . . . . . . . . . . . . . .

193

COMSOL 5.1 API Changes . . . . . . . . . . . . . . . . . .

194

COMSOL 5.0 API Changes . . . . . . . . . . . . . . . . . .

197

CONTENTS | 9

10 | C O N T E N T S

1Release Notes
COMSOL Multiphysics® version 5.5 includes the new Metal Processing Moduleand Porous Media Flow Module; extended and improved versions of the
Application Builder, COMSOL Compiler™, COMSOL Server™, and COMSOLMultiphysics®; as well as updates and improvements for all COMSOLMultiphysics® add-on products. These Release Notes provide information
regarding new functionality in version 5.5 for all COMSOL® software products.

11

New Products
Metal Processing Module
The Metal Processing Module is a new add-on to COMSOL Multiphysics. Using thismodule, you can study how metallurgical phase transformations change themicrostructure of a metallic material during a heating or cooling process. An example
is the quenching of automotive steel transmission components, where the resulting
microstructure is tailored to meet specific demands on strength and durability. Other
examples include the study of phase transformations that occur during additive
manufacturing of metal components and phase transformations in the heat-affectedzone during welding. By combining the Metal Processing Module with the Heat
Transfer Module, you get enhanced heat transfer functionality. Similarly, by combining
the Metal Processing Module with the Structural Mechanics Module and its add-on
modules, you get enhanced functionality for modeling boundary conditions, loads,
and mechanical material behavior.

Porous Media Flow Module
The Porous Media Flow Module extends the COMSOL Multiphysics modelingenvironment to the quantitative investigation of mass, momentum, and energy
transport in porous media. It is designed for researchers, engineers, teachers, andstudents, and it suits both single-physics and multiphysics modeling.
By combining the Porous Media Flow Module with the Heat Transfer Module, you
get enhanced heat transfer functionality and the ability to model moisture transportwith turbulent flow. Similarly, by combining the Porous Media Flow Module with theChemical Reaction Engineering Module, you get enhanced functionality for modelingreversible, irreversible, and equilibrium reaction kinetics in free and porous media flow.

12 |CHAPTER 1: RELEASE NOTESC O M S O L M ult i ph ysi cs
General New Functionality
NEW FLEXNET VERSIONThe FlexNet license server has been upgraded from version 11.15.1 in COMSOL
version 5.4 to version 1.16.2 in COMSOL version 5.5, so to run COMSOL version
5.5, you need to upgrade the license server.
UPGRADED JAVA VERSIONCOMSOL 5.5 includes the AdoptOpenJDK 8 runtime update 222.
SUPPORT FOR IDLE TIMEOUT OF LICENSES

The license administrator can now specify an individual timeout value for each license
feature using the keywords TIMEOUT and TIMEOUTALL in the LMCOMSOL.opt
options file.
INSTALLER IMPROVEMENTS• You can now choose to install COMSOL products with previews of the applications
and example models in the Application Libraries for selected products or for all
products.
• It is possible to use another Java® 8 runtime that you have licensed and installed.
• The look and feel of the installer has been improved.

New Functionality in the Application Builder
ADD-INS

There is now support for creating add-ins. Add-ins, or add-in programs, are extensions
to the COMSOL Multiphysics software and make it possible to share methods andsettings forms between models. You create them like applications using the tools in the
Application Builder, and then define the add-in using the new Add-in Definition, FormDefinition, and Method Definition nodes in the Application Builder. The add-in thenbecomes available from the Add-ins menu in the Developer toolbar. There is also an Addin Libraries window that contains example add-ins and where you can add user-defined
add-in libraries.

COMSOL MULTIPHYSICS|

13

FILE DECLARATION AS THE TARGET

Command-line arguments for applications can now use a file declaration as the target.
The argument value has to be a file on the client file system. Using a file declaration as
the target is not supported when running the web client.
BRINGING ASSOCIATED EDITORS TO THE TOP

Selecting a Form or Method in the Application Builder tree brings its editor to the top
if it is open. This functionality can be turned on and off using the Link with Editor
button found in the Application Builder window’s toolbar.
CHANGED SHORTCUT KEYS

The shortcuts for moving from the Model Builder to the Application Builder and viceversa are now Ctrl+Shift+A and Ctrl+Shift+M, respectively (instead of Ctrl+Alt+A andCtrl+Alt+M).
IMPROVEMENTS TO THE FORM EDITOR• You can now specify the line thickness and line color for Line form objects.
• There is a new Add New Form button in the Panes section header in the Form
Collection object’s Settings window. Clicking it creates a new form and uses it in theForm Collection. The Add Choice List buttons, found in the Settings windows for
Combo Box and other form objects relying on choice lists, have also been moved tothe section header.
• The RGBA option for the Graphics form object background color has been replacedwith Custom, where a custom color can be selected from a color palette. The color
setting is located in the Appearance section of the Settings window for the Graphics
form object. Existing RGBA values are converted to their Custom counterparts.
• The Graphics form object now supports more detailed control over which standard
toolbar groups to display.
• The background color of the Graphics form object’s toolbar is now controlled by a
Background color setting, which is located in the Toolbar section of the Settings
window for the Graphics form object.
• The Edit Custom Information Card dialog box has been redesigned to have the same
appearance as the Edit Custom Toolbar Item dialog box. In addition, it is now possible
to add custom icons through the Edit Custom Information Card dialog box.
• The Button and Toggle Button form objects’ style has been separated into size andstyle. The previous Small, Large, and Flat styles have been replaced by Small and

14 |CHAPTER 1: RELEASE NOTESLarge sizes and Flat and Raised styles. The Style list is available when Size is set toLarge.
• The onLoad and onClose form events are now run when a form is referenced in a
Form Reference, Form Collection, or Card Stack form object. Previously, the eventswere only run for referenced forms when switching between forms in a Form
Collection.
IMPROVEMENTS TO THE METHOD EDITOR• You can now run methods directly in the Application Builder by right-clicking the
Method node and choosing Run. This functionality is not available for form methods
and methods with arguments.
• The keyboard command for the Check Syntax action in the Method ribbon has beenchanged to F9 from F8, used in earlier versions. The Compile Application action
found in the toolbar in the Compiler node’s Settings window now has F8 as its
keyboard command. F8 is also the keyboard command for the Create Add-in action
found in the toolbar in the Add-in Definition node’s Settings window.
IMPROVEMENTS AND CHANGES FOR THE APPLICATION LANGUAGE

These methods have been added or changed:• For add-ins, the following new static methods are now available to retrieve the entityof a specific type that is considered the working entity in the COMSOL Multiphysics
desktop window:
Use ModelNode getCurrentComponent(); to get the current component.
Use MeshSequence getCurrentMesh(); to get the current mesh sequence.
Use Physics getCurrentPhysics(); to get the current physics interface.
Use ResultFeature getCurrentPlotGroup(); to get the current plot group.
Use Study getCurrentStudy(); to get the current study.
The selectNode method has been complemented by a method to retrieve theselected Model Builder tree node:
ModelEntity getCurrentNode();• Conversion methods for float types to double types have been added:
double toDouble(float value)
double[] toDouble(float[] value)
double[][] toDouble(float[][] value)

COMSOL MULTIPHYSICS|

15• The new function clearDebugLog() clears the Debug Log windows in the Model
Builder and the Application Builder.
• The utility method String getClientFilePath(String) has been changed toonly return the filename part of the path when called from an application runningin a web browser.
• The expanded state of sections in form collections can now be controlled using
app.form("form1").formObject("formcollection1").
expanded("form2", false);• The expanded method is only supported by form collections that use sections. The
first argument is the tag of the form that is represented by the section. The second
argument determines if the sections should be expanded or collapsed.
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.

New Functionality in COMSOL Compiler™
• You can now download and install the COMSOL Runtime™ separately whenneeded. The files for the compiled applications can then be much smaller because
they no longer include the runtime. The runtime will be installed in
C:\Program Files\COMSOL\COMSOL55\Runtime

When compiling an application, you can choose if the runtime should be
downloaded or embedded in the compiled application.
• COMSOL Compiler now supports file larger than 4 GB on Windows® by using an
external payload file with a .dat extension that the COMSOL Compiler creates
automatically.
• The support for icons has been extended. You can now specify icon images for eachindividual platform selected for compilation. The supported formats for the icons
are:- For Windows®: ico, png, and bmp.
- For Linux®: png and bmp.
- For macOS: icns, png, and bmp.
• The Settings window for the Compiler node now supports compiling applications
that include custom physics interfaces created using the Physics Builder. You canchoose to include Physics Builder development files, an external archive folder, or

16 |CHAPTER 1: RELEASE NOTESan external Java archive (JAR file), if you have enabled the Physics Builder in the
Preferences dialog box.

New Functionality in COMSOL Server™
The default COMSOL Server appearance has been updated, and the icons for
COSMOL Server and COMSOL Client are now the same as for COMSOLMultiphysics.

New and Improved General Functionality in COMSOL Multiphysics
RIGHT-CLICK TO DEFINE SELECTIONS AND ADD PHYSICS FEATURES

It is now possible to right-click in the Graphics window to create a selection ofgeometric entities that acts as a preselection. You can then, if a physics interface node
is selected in the Model Builder, right-click and add any applicable physics feature tothat physics interface. While in this preselection mode, where the Activate Selection
button is turned off in the physics feature’s Settings window, you can select additional
geometric entities and add them to the selection for the added physics feature or toanother physics feature that you add from the context menu (or the Physics toolbar).
CHANGES TO PHYSICAL CONSTANTS

The values of the following physical constants have been updated according to new
International System of Units definitions:• Avogadro constant, from 6.022140857e23 1/mol to 6.02214076e23 1/mol.
• Boltzmann constant, from 1.38064852e-23 J/K to 1.380649e-23 J/K.
• Elementary charge, from 1.6021766208e-19 C to 1.602176634e-19 C.
• Planck’s constant, from 6.626070040e-34 J·s to 6.62607015e-34 J·s.
• Permittivity of vacuum from 8.854187817e-12 F/m to
1/mu0_const/c_const/c_const.
• Permeability of vacuum from 4*pi*1e-7 H/m to
2*alpha_const*h_const/c_const/e_const/e_const.
SHOW MORE OPTIONSThe Show More Options settings for activating some advanced options have been moved
from a menu to a dialog box (still accessed from the Model Builder toolbar) and split
into more categories. Some categories have also been added. In addition to controlling

COMSOL MULTIPHYSICS|

17

content in the Model Builder tree, now the ribbon content can also be updated insome cases.
SELECT BOX AND ZOOM BOX

It is now easier to use the Select Box, Deselect Box, and Zoom Box buttons multiple times
in a row by keeping them enabled after the initial usage using the Keep Enabled After
Use option. The Keep Enabled After Use option, when selected, keeps the corresponding
selection mode active until you click the button again or right-click in the Graphics
window. For Select Box and Deselect Box, there are also the new options Entity Intersects
and Entity Inside so that you can choose whether geometric entities that the box
intersects should be selected or deselected (Entity Intersects) or ignored unless they are
fully inside the box (Entity Inside) as in earlier versions. The latter behavior is thedefault setting.
IMPROVED COPY-PASTE FUNCTIONALITY BETWEEN MODELSThe Model Builder nodes that you can copy-paste within models and between
COMSOL sessions have been extended to also include:• Functions• Materials• Under the Definitions branch, the nodes that relate to moving mesh, deformed
geometry, optimization, and shared properties.
• Nodes under the Multiphysics branch.
• Plot groups and Plots• Derived values• Export nodes
Pasting to another model always does so using a best-effort principle, ignoring invalid
settings. In a plot group, for example, the available settings depend a lot on theavailable datasets and solutions.
GRAPHICS WINDOW TOOLBAR IMPROVEMENTS

You can now control how to display buttons in the Graphics window toolbar using theGraphics Toolbars page in the Preferences dialog box. You can configure it to display
toolbar items that you frequently use at the top level and place less common items indrop-down menus. There are four options for the buttons: Normal, Compact, Wide, andHidden.

18 |CHAPTER 1: RELEASE NOTESIMPROVED COMPARISON RESULTS TOOLSIn the Comparison Results window, the following new tools are available forcomparisons of applications and models:• In the Comparison Results window’s toolbar, there are new buttons for creating a
new comparison and for showing the next or previous difference.
• There is now an option for only including active settings.
• You can double-click nodes in the tree (or right-click and choose Go to Source) tomove to the corresponding node in the Model Builder or Application Builder tree
for the local file. When applicable, you can choose Go to Remote Source to move tothe corresponding node in the Model Builder or Application Builder tree for the
remote file.
IMPROVED SEARCH FUNCTIONALITY IN THE APPLICATION LIBRARIESWINDOW

The search functionality for finding applications and models of interest in the
Application Libraries window has been improved with the following functionality:• Disabled nodes are now ignored.
• You can search keywords for type, tag, and label using the prefixes @type, @tag, and@label, respectively.
IMPROVED ORGANIZATION OF THE TOOLS UNDER DEFINITIONS

The tools under the Global Definitions and Definitions nodes have been expanded andreorganized. Some changes compared to version 5.4:
• The Component Couplings menu has been renamed Nonlocal Couplings.
• The Model Input and Ambient Properties options are now available under Shared
Properties.
• Under Global Definitions, Common Model Inputs has been renamed Default Model
Inputs.
MISCELLANEOUS IMPROVEMENTS AND CHANGES• A new Calculated values option in the Excel Save and Excel Load dialog boxes forexport and import of table data. This option determines if the Value column is
included in the exported data.
• It is now possible to move variables from one Variables node to another Variables
node.

COMSOL MULTIPHYSICS|

19• You can now copy, paste, and duplicate the Hide for Geometry and Hide for Physics
nodes and move them up and down in the model tree.
• In the root node’s Properties window, there is a new Search path field, where you
can specify a search path for external files.
• The Developer node under Global Definitions has been removed. Its children now
appear directly under Global Definitions.
• There is a new preference setting: Check for recovery files at launch, which is selectedby default. This setting controls if the Recovery Files window will appear at launchwhen there are any recovery files.
• You can now switch between model components using the Component menu in the
Model section of the Home toolbar.

New Functionality in the Physics Interfaces• The Nonisothermal Flow interface is now available in COMSOL Multiphysics forlaminar flow.
• The Stabilized Convection-Diffusion Equation interface includes new interior
boundary conditions with Dirichlet and flux options.
• The default feature in the Global ODEs and DAEs interface is now removable.
• The Laminar Flow interface has new default values for density, 1000 kg/m3, anddynamic viscosity, 10−3 Pa·s, when the User defined option is selected.
• In tensor definitions for physical properties, Anisotropic has been changed to Full forthe full 3-by-3 definition of an electrical conductivity, for example.
• For the PDE, Boundary Elements interface, the behavior for antisymmetry and zerocharge at infinity has been improved.
• The behavior for pair selection in the physics interfaces has been improved. You can
now add pairs using an Add dialog box.

New Geometry and Mesh Functionality
GEOMETRY FUNCTIONALITY• For 2D geometry modeling, a new Sketch mode is available for interactively creatinggeometries in the Graphics window for a 2D geometry or part, or in a work plane
for a 3D model. On the Sketch toolbar, you can choose to create the following 2D
geometric objects: Circular Arc, Interpolation Curve, Quadratic and Cubic Bézier
curves, Rectangle, Square, Circle, and Ellipse. If you have a license for the Design

20 |CHAPTER 1: RELEASE NOTESModule, the Sketch toolbar also contains buttons for creating geometric constraints
and dimensions. The snapping has also been improved and extended to include
snapping to existing lines and circles and the possibility to snap lines and circles thatyou draw to existing points, lines, and circles.
• The Part Library for COMSOL Multiphysics has been extended and now includes
the five Platonic solids (cube, tetrahedron, octahedron, dodecahedron, andicosahedron), a propeller with constant pitch, and a random flat surface.
• There are now more ways to rotate 3D geometry objects: In the Rotate feature, you
can choose to specify an axis or rotation or to specify Euler angles. This option is
also available in Work Plane features defined using the Transformed plane type and in
the Part Instance nodes in the Position and Orientation of Output section. For the
Rotate feature, there is also a new Angle field when you have selected to specify theaxis of rotation, where you can add a vector of angles for creating multiple rotatedobjects.
• The geometry measurement information has been extended with the dimensions of
the bounding box and the average coordinates (when you have selected two points).
• For 1D geometries, you can now specify intervals using interval lengths in addition
to specifying coordinates in the Settings window for Interval nodes.
• The Move and Copy features now include a Specify list in the Displacement section
with the options Displacement vector and Positions, which is a new option to specify
the move using a vertex or coordinates for the old position and vertices orcoordinates for the vertices to move to.
• If your license includes the CAD Import Module or any of the LiveLink™ products
for CAD, you can export the geometry on the IGES and STEP formats.
• The geometry code and serialization have been improved and made more efficient.
MESHING FUNCTIONALITY• For import of meshes on the STL and VRML formats, there are now separate STL
and VRML file format options to choose from as the source in the Import node formesh import. Also, for STL file import, there is now a Create selection check box. If
you select it, a boundary selection of every solid section in the file is created during
import.
• Mesh element shape optimization, which can result in curved elements inside thedomain, is now available and is active by default. Interior elements are curved to
improve the quality and avoid inverted higher-order elements. The new Avoid
inverted elements by curving interior domain elements check box is available in the
Settings windows for the main Component nodes and is selected by default.

COMSOL MULTIPHYSICS|

21• New Create Vertices and Create Edges mesh features are available in 2D and 3D for
empty geometries. Additionally, Create Faces and Create Domains are available foradding faces and domains on imported 3D meshes. There is also a Fill Holes featurefor filling holes in imported surface meshes. You find these tools on the Create
Entities menu on the Mesh toolbar and when right-clicking the main Mesh node.
• You can now import and export 3D surface meshes on the PLY format (the Polygon
File Format or Stanford Triangle Format) and the 3MF 3D printing format. You canchoose to export and import to and from *.ply files as a PLY binary file or PLY
text file and to and from *.3mf files as a 3MF file. You can also import and export
meshes on the Sectionwise format.
• When exporting meshes on the COMSOL Multiphysics binary and text formats, a
new Export as second-order elements check box is available. It is cleared by default,
which means that the exported mesh contains linear elements.
• The Adapt node has been enhanced with the following new functionality:- For the General modification adaptation method, a Maximum coarsening factor
setting is now available under the Allow coarsening check box.
- For the Regular refinement and Longest edge refinement adaptation methods, a
Maximum number of refinements setting is now available.
- Under External changes, there is a Reevaluate with Updated Model button and an
Update when parameter is changed list for selecting the parameter to notice anychanges so that it affects the adaptation if it is used in a mesh size expression, forexample.
• Free quad meshes for planar faces and 2D domains with concave corners have been
improved using a new scheme in version 5.5. This new functionality is enabled bydefault in the Free Quad and Swept operations. It can be disabled by selecting
Legacy version 5.4 under Tessellation in a Free Quad node or by selecting Quadrilateral(legacy version 5.4) from the Face meshing method list under Sweep Method in a Swept
node.
• Logical expressions for mesh functionality now support the built-in variables h (thelocal mesh size) and qual* (mesh quality measures).

22 |CHAPTER 1: RELEASE NOTESNew and Updated Operators, Functions, and Definitions• New built-in mathematical functions:- binomial(n,k) — binomial coefficients.
- factorial(n) — factorial of nonnegative integer.
- legendre(l,x) and legendre(l,m,x) — Legendre polynomials and associatedLegendre functions.
- zernike(n,m,r,phi) — Zernike polynomials.
- sphericaly and sphericalyr — spherical harmonic and real sphericalharmonic functions, respectively.
• New variable utilities under Definitions:- Vector Transform: for transforming a vector of component expressions from one
coordinate system to another.
- Matrix Transform: for transforming rows or columns of a matrix of component
expressions from one coordinate system to another.
- State Variables: for defining dependent variables that are updated using an update
expression before or after each completed solver step.
- Expression Operator: for defining an operator that evaluates to arbitrary
parameterized expressions on specified selections. You can also add Operator
Contribution subnodes to an Expression Operator node.
• A new operator, stddev, is available for computing the standard deviation, using an
integration or summation operator as its first input argument.
• New operators for time derivatives in different frames: frame.dt(<expr>), whereframe is the type of frame: spatial, material, geometry, or mesh.
• New units:- The ounce as oz and ounce, equal to 1/16 pound (0.028349523 kg).
- The fluid ounce as fl_oz and fluid_ounce, equal to 1/160 imperial gallon(2.8413063·10−5 m3)- The rayleigh as rayl and rayleigh (SI version, equal to 1 Pa·s/m) and
rayl_cgs and rayleigh_cgs (CGS version, equal to 10 Pa·s/m), used formeasures of specific acoustic impedance.
• A new Combined System coordinate system, which can be used in 1D, 2D, and 3D
when you want to refer to different coordinate systems in different domains, is now
available.

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• 3D Rotated System coordinate systems are now also available in 2D so that you
define general rotations using 3D Euler angle inputs.
• In the Material Browser, you can now reload material libraries by right-clicking amaterial library node and choose Reload Selected.
• For external material functions, there are new reserved return values: the return
value −1 is now interpreted as a normal exit with a warning message; the return value−2 is interpreted as a normal exit with a log message. Both values previously
indicated an unspecified error condition. Also, you can now add two newelectromagnetic options: general H(B) relation and the General B(H) relation.
IMPROVEMENTS FOR MOVING MESHES AND DEFORMED GEOMETRIES• Similar functionality for defining deformed geometries is now available in the
Deformed Geometry submenu under Definitions, as were previously available formoving meshes.
• A new Rotating Boundary feature is available under both Moving Mesh and Deformed
Geometry for defining boundaries of a geometry that is rotating. You can specify therotation type and the rotation axis.
IMPROVEMENTS FOR LAYERED MATERIALS• The layers in the Layered Material Link, Layered Material Stack, and Layered Material
Stack Link nodes can be transformed as Symmetric, Antisymmetric, and Repeated.
• The Single Layer Material node has been deprecated in version 5.5. Instead, allstandard boundary materials can be switched to a single layer material in one of thefollowing ways:- By adding a Shell property group into the standard material node. You need toenter a thickness to let this material become a single-layer material.
- Select Single Layer Material from the Material node’s Layers submenu. Doing so
will add a blank material together with a Shell property group as a subnode andset a default value of 1e-4[m] for the thickness.
- Assign a value to the requested thickness in the Material Contents table.

24 |CHAPTER 1: RELEASE NOTES• Changes for the Layered Material node:- The default selection of the interface material has been changed from None to
From layer, which means that the interface material properties will be computedfrom the adjacent layers’ material properties by default.
- A standard Material node in the global component can turn into a layered material
by adding a Shell property group.
- The layer thickness of a layered material can be a number or a parameter.
• For the Layered Material Link and Layered Material Stack nodes, the default selectionof the nonlayered material has been changed from None to Same as layered material.
It means that the nonlayered material properties are computed as an average valueof the layers’ material properties.
• Improvements for layer thickness variation:- The layer thickness can be scaled with a factor that can depend on geometry
variables. The scale property is available in the settings for Layered Material Link,
Layered Material Stack, and Layered Material Stack Link nodes.
- The thickness of a single-layer material can be a number, parameter, or value.
- When a layer is defined with a scaling factor, it will be seen in the preview
windows with a darker color than a nonscaled layer.

New Functionality in Studies and Solvers
STUDIES AND STUDY STEP FUNCTIONALITY• For adaptive mesh refinement, it is now possible to choose on which geometric level
the mesh adaptation will be performed, so that you can do adaptive mesh refinementon surfaces, for example. You specify the geometric entity level in a new Geometric
Entity Selection for Adaptation section in the main study step’s Settings window. In
that section, you can also select for which domains or surfaces, for example, toperform the mesh adaptation (that is, you can do adaptive mesh refinement in a
subset of the geometry).
• It is now possible to add a number of global goal-oriented quantities to make themesh adaptation terminate when those quantities are stable to a requested accuracy.
These goal-oriented quantities could, for example, be the S-parameters for an RF
simulation. The goal-oriented termination can be used for any error estimation
method supported by the adaptation and error estimates algorithm. Choose Manualfrom the Goal-oriented termination list under Adaptation and Error Estimates in the

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study step’s Settings window to enter user-defined goal-oriented quantities andtheir tolerances.
• For time-dependent adaptive mesh refinement, the General modification method andRebuild mesh methods are now available in the Adaptive Mesh Refinement node’s
Settings window. The general modification method can resolve sharp fronts withfewer mesh elements in total compared to the previous methods.
• Select the new Plot the location of undefined values check box in the Settings window
for the main Study node to create a separate window that contains a plot that shows
the location of any undefined values, such as Inf or NaN, which can help you locate
a problematic part of the model.
• All model tree nodes that can appear in the Modify model configuration for study step
tree now include a Disable in All Studies option in their context menus if there is atleast one study step where the Modify model configuration for study step check box isselected; this option simplifies disabling a model tree node in several study steps.
• In the Optimization study step’s Settings window, a new Enforce design constraints
strictly check box is available in the Constraints section for derivative-free
optimization solvers that support the penalty constraint handling method (Nelder–
Mead, Coordinate search, and Monte Carlo) and for COBYLA. If selected, thesolver evaluates all design constraints before the forward problem is run. If infeasible
constraints are found, the forward problem is not run, and the optimization solver
proceeds to the next iteration.
SOLVER FUNCTIONALITY• A new Domain Decomposition (Schur) solver is now available to provide domain
decomposition using an exact Schur complement and an algebraic hybrid directiterative solver. The Domain Decomposition solver in earlier versions of COMSOLMultiphysics is now available as Domain Decomposition (Schwarz).
• It is now possible to stop iterative improvements if the residual is not reduced byusing the new Error ratio bound setting in the solver’s Settings window’s Error
section. By default, it is set to 0.5 (valid values are between 0 and 1; a lower valuemeans that the iterations terminate more quickly). When the Check error estimate
setting is set to Automatic, a single warning of Iterative refinement triggered
appears in the Log window if the iterative refinement is triggered.
• An Upper Limit node is now available under the Segregated solver node to specify anupper limit for field values in a similar way as for the already available Lower Limit
node.

26 |

CHAPTER 1: RELEASE NOTES• The MUMPS solver has been upgraded to version 5.2.1 and now supports blocked
low-rank factorization, both when computing the LU factors and when storing
them. This is an approximate but accurate LU-factorization method that canpotentially save memory in your models. You activate it by selecting the Block low
rank factorization check box in the Settings window for the MUMPS direct solver.
• For the Generalized Alpha and BDF methods, when Backward Euler is selected forthe consistent initialization, there is a new Rescale after initialization check box.
Select it, for example, in fluid-flow models that can suffer from a bad initial scaling
due to a zero initial value for the velocity, to provide a smooth start and avoid using
too small time steps.
• You can now get a log and plot of errors per field and state during the solution for
applicable multiphysics models if you select Detailed from the Solver log list in the
Advanced node’s Settings window.
• A new Lower element order first (any) setting is available for the algebraic multigrid(AMG) and smoothed aggregation AMG (SAAMG) solvers. It makes it possible touse the combination of first using the geometric multigrid (GMG) solver with lower
order until order 1 is reached and then using the AMG or SAAMG solver togenerate the coarser levels in a multigrid approach. The advantage with the new
setting is that you can control the total number of multigrid levels in one setting andthat you do not have to repeat the pre- and postsmoother settings in two places.
• For controlling oscillations around discontinuities and for stabilizing thecomputations of typically nonlinear conservation laws, a WENO (weighted
essentially nonoscillatory) limiter has been added to the discontinuous Galerkinmethod. WENO is available for the Wave Form PDE interface and for theCompressible Euler Equations interface in the CFD Module. In those physics
interfaces, select WENO from the Limiter list to activate the WENO limiter in themain interface nodes’ Settings window.
• You can now specify a maximum value for the scaling of eigenvectors in the Settings
window for the Eigenvalue Solver node by choosing Maximum from the Scaling of
eigenvectors list and then entering a value in the Maximum absolute value field. The
peak value is then normalized to that value. You can use this setting to keep
eigenmodes small.
CLUSTER AND BATCH FUNCTIONALITY• For saving solutions on a cluster, you can now right-click a Solution node and choose
Store Solution Using Distributed Storage to store the solution using a distributed
storage on clusters, which can improve performance using parallel I/O.

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• There is a new Keep solutions before and after stop condition check box under the
Stop condition field in the Parametric Sweep node’s Settings window under Job
Configurations. Using this option, you can store solutions for the parametricsolutions both before and after the stop condition has been satisfied.
• A new -batchlogout option for batch runs is available to direct the log to standard
out when storing on file.
• A new -norun option for batch runs is available for not running the model, which
can be useful if you, for example, just want to run -clearsolution or-clearmesh for a model that already includes a solution or mesh and then save it,
without a solution or mesh, without computing the model first.

New and Improved Results and Visualization Functionality
NEW AND IMPROVED DATASET AND EVALUATION FUNCTIONALITY• Using the new Filter dataset, you can filter another dataset’s geometry with respect
to an expression. It is also possible to create a mesh part from this dataset by rightclicking it and selecting Create Mesh Part.
• The Image export feature has been improved:- The previous 1D Image, 2D Image, and 3D Image export features have been
merged to a single Image feature.
- The Image export feature can now export images of many more things than plotgroups, such as geometries, meshes, and selections for physics features.
- You can create custom presets that specify the image size as well as what toinclude in the exported image.
- The export target can now also be the clipboard and PowerPoint® (on Windows®
only) in addition to the file target.
• Evaluation groups now support all evaluation features.
• It is now possible to disable the closing surfaces for incomplete revolutions in
Revolution 2D and Revolution 1D datasets, by clearing the Add end caps if therevolution is not full check box.
• In Evaluation Group nodes, you can now choose Difference and General from the Typelist in the Transformation section. The difference computes the difference of all
evaluations (evaluation1-evaluation2-evaluation3, and so on). The General
option provides the possibility to enter a general expression in an Expression field.

28 |CHAPTER 1: RELEASE NOTESSuch an expression can include global parameters and mathematical and physicalconstants, for example.
• New Global Evaluation Sweep nodes are available under Derived Values and Evaluation
Group nodes. You can use them to vary a small number of model parameters as anevaluation sweep during postprocessing. A global evaluation sweep can be useful for
postprocessing of reduced models, for example.
• It is now possible to do transposed evaluation in evaluation groups by selecting theTranspose check box in the Transformation section of the Settings window for an
Evaluation Group.
• When exporting plot data for 1D plots with multiple curves, it is now possible toexport in a compact format where there is one column containing x-coordinates andone or more columns containing, for example, y-coordinates. To do so, selectAppend as columns from the If multiple curves list.
• In numerical evaluations and plots that can take multiple expressions, the Add
Expression and Replace Expression lists now contain an All expressions in this group
option for some groups of related expressions, such as vector components, so thatyou can add all of them at once.
• In the Mirror 2D and Mirror 3D datasets, you can now choose to remove elements on
the symmetry axis or symmetry plane, respectively. You can use this functionality to
get a plot that only shows relevant edges in the mirror dataset.
• It is now possible to evaluate maximum and minimum values in Gauss points andLagrange points for maximum and minimum datasets, numerical evaluation
features, and plots.
• The Shell dataset is now available also for 2D axisymmetric models.
• It is now possible to make interface and layer selections in the Layered Material
dataset.
• You can now control the precision when exporting tables and evaluation groups toExcel®.
• The export of data to Excel is now also significantly faster than in earlier versions.
NEW AND IMPROVED GRAPHICS AND PLOT FUNCTIONALITY• Selections are now available in the settings for 2D and 3D Plot Group nodes. By
default, the entire geometry is selected, but you can choose to only use the plotgroup in some part of the geometry.
• You can now export images to PowerPoint® in the Image Snapshot window. With
the new add-in for PowerPoint, which can be installed together with COMSOLCOMSOL MULTIPHYSICS|

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Multiphysics, you can work with linked images between COMSOL andPowerPoint. The installer registers the COMSOL Interface add-in with
PowerPoint. When the interface add-in is loaded, it provides the following additions
to the PowerPoint user interface:- The COMSOL ribbon tab, where you can insert and update images.
- The COMSOL tab in the File Backstage View, where you can manage the source
references for the linked images.
- The COMSOL Image tools tab, where you can change image settings.
- The COMSOL contextual menu, where you can quickly access the most usedcommands.
• In the Expression sections in the Settings windows for plot nodes, you can now use
Plot Next Expression and Plot Previous Expression buttons to step though allpredefined expressions in a group of expressions in the Replace Expression tree.
• You can now control how numbers are formatted in the title and the parameter
indicator. In the Title section for the plot group nodes, there is a new Number format
list with the following options: Default, Automatic, Engineering, Scientific, Stopwatch,and Scientific stopwatch with associated settings for controlling the number format.
• Streamline plots now support interactive spheres (points) as well as interactive
arrows. It is also possible to generate animations of the interactive spheres and ofarrows that move with the field.
• The color scale in plots can now be defined as the gradient between two colors.
• You can now export 3D surface plots on the PLY format (the Polygon File Format
or Stanford Triangle Format) and the 3MF 3D printing format. You can choose toexport to *.ply files as a PLY binary file or PLY text file and to *.3mf files as a 3MF
file.
• For 3D image export in the glTF™ format, there is now an option to not include
line segments. Lines segments are not supported by all glTF viewers.
• In 1D plots, a new Manual option is available for placing the legend box freely in aposition that you provide as x- and y-coordinates.
• In plot titles, you can now evaluate expressions in manual parameter indicators.
• In Filter subnodes to plot nodes, a Use derivatives check box is now available when
the Element nodes to fulfill expressions setting is Smooth. Select it to use cubic
interpolation in, for example, postprocessing of topology optimization models.
• Arrow plots in 2D and 3D can now use double arrows to, for example, illustrate
moments in solid mechanics.

30 |CHAPTER 1: RELEASE NOTES• For Arrow Volume, Coordinate System Volume, and Principal Stress Volume plots in
3D, a new Placement list provides the options to place the arrows or symbols in a
Grid, Gauss points, or Mesh nodes. For Arrow Surface, Coordinate System Surface, andPrincipal Stress Surface plots in 2D, you can choose Grid or Mesh nodes. For similarplots on lower dimensions (such as an Arrow Line plot in 2D), the position settings
are available in a separate Arrow Positioning or Positioning section.
• Histogram plots include a new normalization setting. Select Sum of values to divide
the absolute count of each bin by the sum of the counts over all bins. Select Integral
to divide the absolute count of each bin by the sum of the counts over all bins, each
multiplied by the width of the bin. The new Sum of values option is equivalent to
the Integral option in previous versions.
• When you define the number of contour or isosurface levels in Contour and
Isosurface datasets and in Contour, Isosurface, and Directivity plots, a new Round thelevels check box is available and selected by default to provide a rounded uniform
step between the levels.
• You can now add Deformation subnodes to Annotation plot nodes so that annotations
can be moved corresponding to a deformed surface plot, for example.
• Deformation subnodes are also available for 2D and 3D Radiation Pattern plots.
• Directivity plots are now available in 1D plot groups.
• Support for plotting matrix variables has been added to the following plot types:
Coordinate System Surface in 3D and Coordinate System Line in 2D and 3D (choose
Matrix variable from the Source list).
• A time resolution setting is now available in a Quality section in Global and Point
Graph 1D plots referring to a time-dependent solution.
• The Reference direction settings are now available also for 1D Radiation Pattern plotsof 2D models.
• There is now an option to show the axial symmetry line in 2D plots that refer to adataset with a 2D axisymmetric geometry.
• Whirl plots can now handle multiple rotors.
• It is now possible to plot ellipses without arrows in the trajectory plots.
• You can now display the interfaces between layers in Through Thickness plots. You
can also choose a length unit for the thickness coordinate.
• It is now possible to evaluate at multiple locations in Layered Material Slice plots. The
Location definition list contains two new options: Interfaces and Layer midplanes. In
addition, the Local z-coordinate field now accepts an array of values. In a new Layout

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section, you can define the displacements as Linear or Rectangular and select anorientation of the displacements. You can also select a Show description check box toadd an annotation (the z-coordinate, layer, or interface numbering, depending on
the through-thickness location). Using this functionality, you can create a plot that
required several Layered Material Slice and Annotation plots in previous versions.
Layered Material Slice plots are now also available in 2D models and can, in 3D
Layered Material Slice plots, evaluate in Revolution 2D datasets that refer to 2D
axisymmetric solutions containing layered materials. There are also location input
and location definition settings in numerical evaluation nodes such as Volume
Average, Volume Integration, Volume Maximum, and Volume Minimum for 3D models
that contain a layered material.
• You can now add a Filter subnode to Through Thickness plots.

New Java® API Methods
LOADING AND SAVING FILES FOR PARAMETRIC SWEEPS

The loadFile(String filePath) and saveFile(String filePath) Boolean
methods are now available to load and save files for the parametric sweep feature.
These functions work if the type of feature is Parametric Sweep and save information
concerning either all combinations or specified combinations; otherwise, they returnfalse. The functions also return false if the operation is not successful; otherwise, they
return true.
IMAGE OBJECT FOR MESH FEATURES

The image() object for mesh features includes a new property to set the selection.
model.mesh("foo").feature("bar").image().set("selection", "main")specifies that the feature’s main selection,model.mesh("foo").feature("bar").selection(), will appear in the plot. This is

the default.
model.mesh("foo").feature("bar").image().set("selection",<propname>)

specifies that a property selection,model.mesh("foo").feature("bar").selection(<propname>), will appear in

the plot.
For mesh features that do not have any selection, the selection property is ignored
when plotting.

32 |CHAPTER 1: RELEASE NOTESONLY PLOT WHEN REQUESTED

The following methods have been added to the API for plotting only when requested:void setOnlyPlotWhenRequested(booleanvalue);

to set if plots selected in the Model Builder only should be updated when the user
explicitly requests it.
boolean isOnlyPlotWhenRequested();returns true if plots selected in the Model Builder only should be updated when theuser explicitly requests it.

General Backward Compatibility Considerations
COMSOL Multiphysics version 5.5 can open MPH-files saved from COMSOLMultiphysics versions 4.0–5.4.
COMSOL Multiphysics version 5.5 can run Java® files saved from COMSOLMultiphysics versions 4.0–5.4. However, the Java® files may need to be modified inaccordance with information following in this document and may need to berecompiled with the comsol compile command in version 5.5.

Backward Compatibility with Version 5.4
GEOMETRY REPRESENTATION ARRAYS

To reflect the new serialization format for 3D objects represented using the COMSOL
kernel, the meaning of the arrays returned from the GeomInfo methods getFace,
getPVertex, and getPEdge applied to a 3D geometry object has changed slightly inversion 5.5. In version 5.4, row 3 of getFace contained the index of the surface in thelist of all manifolds (curves and surfaces) in the geometry object. In version 5.5, it isinstead an index in the list of all surfaces in the geometry object. Similarly, row 5 of
getPVertex and row 9 of getPEdge now contain an index in the list of surfaces
instead of an index in the list of manifolds.
INTERPOLATION CURVES

For the Interpolation Curve geometry feature, the default end conditions have beenchanged from Zero curvature to None. In the API, the default has been changed fromzerocurv to none. In addition, the algorithm has been changed for the case when Typeis Open curve and Relative tolerance is 0, which can give a slightly different shape of thecurve.

COMSOL MULTIPHYSICS|33

SCALING 2D GEOMETRY OBJECTSIn version 5.4, you could scale and move a set of selected 2D objects in the Graphics
window by dragging its bounding box. In version 5.5, you can still move objects by
dragging, but scaling requires adding a Scale feature in some cases.
FREE QUAD MESHING

Models saved in versions 5.3 to 5.4 with the free quad tessellation method set toAutomatic (in a Free Quad feature) or face meshing method set to Quadrilateral (in a
Swept feature), will, when opened in version 5.5, have the tessellation method or facemeshing method set to Legacy version 5.4 or Quadrilateral (legacy version 5.4),
respectively.
PARTICLE TRAJECTORIES STUDY STEP

The Particle Trajectories study step has been removed in version 5.5. Instead, use aTime Dependent study step, which has exactly the same settings.
IMAGE EXPORT PROPERTIES

For image export features, the properties options, title, legend, logo, and axes
have been split into three properties in version 5.5, one for each spatial dimension. For
example, options1d, options2d, and options3d. axes does not exist in 3D. The
same change has been done for all image() features.

Backward Compatibility with Version 5.3a
ADAPTATION AND ERROR ESTIMATES

The property rmethod has been renamed meshadaptmethod, with additional possible
values. The old property (rmethod) and its values can still be used.
MASS PROPERTIES AND MASS CONTRIBUTIONSIn the Density section, the Integration frame list in previous versions is now called
Density input frame.
In the API, the corresponding property name has been changed from
integrationFrame to densityFrame.
NO FLUX FORMULATION

The formulation of the No Flux feature has been changed in the Transport of Diluted
Species interface in version 5.4 so that the flux relative to the convective flux is set to34 |CHAPTER 1: RELEASE NOTESzero. The new formulation is used when opening a model from a previous session. In
the previous formulation, the total flux was set to zero.
LEGACY FLAG -DCS.LEFTRIGHTSELECTION HAS BEEN REMOVED

The legacy flag -Dcs.leftrightselection for selections of geometric entities using
left-right click has been removed in version 5.4.
AMD ACML LIBRARIESThe AMD ACML library is no longer supported by AMD. It has been replaced bystandard BLAS and LAPACK as an alternative to Intel MKL. On Linux, the BLIS
library is also available. Intel MKL is still the default BLAS library.
STRICTER SOLUTIONINFO VALIDATIONThe SolutionInfo validation now ensures that SolutionInfo.isValid() returns
true before using other SolutionInfo methods, unless stated otherwise in the
documentation of the methods.

Backward Compatibility with Version 5.3
PDE, BOUNDARY ELEMENTS INTERFACE

The PDE, Boundary Elements interface has been reimplemented and improved.
Backward compatibility is provided for MPH files but not for the Java API.
STABILIZATION IN SOME PHYSICS INTERFACES

Model files created in version 5.3 and earlier retain the old stabilization formulation.
The new formulation is obtained by replacing the physics interface with a new one.
The improved stabilization breaks Model Java-file backward compatibility for timedependent models that contain one of the affected physics interfaces. Please contact
COMSOL Support to learn how to retain backward compatibility for your specific
Model Java-file.
STORE SOLUTION ON DISKThe Store solution on disk option has been removed.
FUNCTIONS IN GEOMETRY FEATURES

The button Rebuild with Updated Functions has been removed from the following
geometry features: Parametric Curve, Parametric Surface, and Sweep. Instead, use theRefresh or Clear Functions button in the function features.

COMSOL MULTIPHYSICS|

35

In the API, the method importData() is obsolete for the geometry features
ParametricCurve, ParametricSurface, and Sweep. Instead, use the refresh()method in the function features.
PARTICIPATION FACTOR

Support for participation factors in the eigenvalue solver has been replaced by a new
and improved Participation Factors feature, which is available under Definitions>Variable
Utilities in a model component for computing participation factors in structural
simulations.
INTERPOLATION CURVES

For interpolation curves, in the case when relative tolerance is zero (which is thedefault), the algorithm in 5.3a has changed so that the shape of the curve becomessomewhat different (while still interpolating the given points).
ITERATIVE SOLVERSFor the iterative solvers, the error handling mechanism has been improved tocontribute to a general robustness of the computation. The improved mechanism isenabled per default and can give the following effects for nonlinear iterations:• Increased total number of linear iterations• Failure with the error “Divergence of the linear iterations”, if the preconditioner isextremely ill-conditioned.
UNITS IN THE SIZE EXPRESSION NODEThe size expression is now interpreted in the model component’s unit system rather
than in the geometry’s unit system. Also, the spatial coordinates (x, y, z, and so on) are
now always in the component’s unit system. In version 5.3, when evaluating on a grid,
the spatial coordinates were in the geometry’s unit system.
STRESS/STRAIN PLOTS

Principal stress/strain plots now evaluate the stresses and strains in the centers of meshelements instead of in the mesh nodes.

Backward Compatibility with Version 5.2a
FRAME DEFINITIONS

In version 5.3a, all frames are always defined. If you open models from version 5.2a or
earlier, there will be a Permanently Define All Frames button under Frames in the General

36 |CHAPTER 1: RELEASE NOTES

section of the Component nodes. When you click the button, all frames are defined, andthe button disappears.
FRAME CONTROLIn previous versions of COMSOL Multiphysics, it was possible to apply multiple
frame-controlling physics on the same selection. For example, it was possible to add
two Solid Mechanics interfaces (with the Include geometric nonlinearity option enabled)on the same selection and solve. In this case, an “override rule” was applied between
the controlling physics, effectively meaning that the last physics in the tree had controlof the frame deformation for the overlapping domains. This situation could cause
unexpected results.
In version 5.3, multiple physics interfaces controlling the same frame are not allowedon the same selection and will cause an error when trying to solve. However, it is still
possible to use multiple frame-controlling physics with overlapping selection, but you
now have to explicitly disable frame control on all but one of the physics. This gives
you better control on what is going on. The functionality to disable frame control forphysics has been incorporated in the Settings window for study steps to allow choosing
different physics to control the frame in different study steps.

Frame-Scoped Variables
Certain variables pertaining to frame deformation are now defined with “frame
prefix”. For example, the relative element volume is now called spatial.relVol.
Previously, these variables were added by the physics interface controlling the frame
deformation so they used a “physics prefix” (for example, ale.relVol). For backward
compatibility of old models, the physics interfaces still define the old variables, but they
are aliases of the new frame variables.
API SYNTAX FOR ERROR HANDLINGThe old syntax for an error
feature("ftag").feature("prob1").feature("error1")

is no longer supported. Instead, use the following documented syntax:
feature("ftag").problem("error1")
FREE QUAD MESHING

Models saved in version 5.2a with the free quad tessellation method set to Automatic(in a Free Quad feature) or face meshing method set to Quadrilateral (in a Swept
feature), will, when opened in 5.3, have the tessellation method or face meshingmethod set to Legacy version 5.2a or Quadrilateral (legacy version 5.2a), respectively.

COMSOL MULTIPHYSICS|

37

Backward Compatibility with Version 5.2
FREE QUAD MESH

The new free quad meshing algorithm is used in new models, but for models createdin earlier versions, the legacy algorithm is used instead. The default for the new method
property is therefore auto in new models, and legacy52 in migrated models.
GEOMINFO CHECK() METHOD

The return value of the check() method in GeomInfo has been removed. Now,
check() issues an error if the geometry is invalid.
THE CONST PROPERTY IN SOLVERSThe const property available for many solvers has been removed in version 5.2a andreplaced with the cname and clist properties, which are string arrays for the constantnames and corresponding constant values, respectively. For the Dependent Variablesnode, the new property initparametersmethod, which can be set to auto (thedefault) or manual, has been added to control automatic synchronization of values ofparameters to use for initial expressions. The Dependent Variables node now also
includes the cname and clist properties.

Backward Compatibility with Version 5.1
CREATING SELECTIONS

In version 5.2, the selresult property replaced the createselection property.
createselection is still supported for backward compatibility.
SELECTIONS IN PART INSTANCESFor backward compatibility for selections in part instances, there is a Keepnoncontributing selections check box, cleared by default, in the Selection Settings sectionof the Settings window for Part Instance nodes. If you select the Keep noncontributing
selections check box, the Keep column is disabled, and the selection is kept if theContribute to value is None. In the COMSOL API, the default is an active Keepnoncontributing selections setting.
MESH PARTS

For backward compatibility regarding STL/VRML import, and for COMSOL API
compatibility, the old user interface for mesh import (with a specified filename andimport properties) and the corresponding properties are available in the COMSOL38 |CHAPTER 1: RELEASE NOTESAPI but not in the COMSOL Desktop, unless it is the active option. This means thatthe old user interface can only be reached if the filename is set in combination with the
STL import type (the API type stlvrml), which cannot be done from the new userinterface.
DORMAND-PRINCE 5 TIME-STEPPING SOLVER

The Dormand-Prince 5 Runge-Kutta solver in 5.1 does not use field norm scaling inversion 5.1 when estimating errors. This means that the errors of, for instance, an ODE
might become very small when solved together with a field with many DOFs, and thetime steps taken might then be too large. In version 5.2a, the Runge-Kutta solver uses
field norm scaling, which means that old models using the Dormand-Prince 5 mightneed tighter tolerances to produce results in earlier versions that are similar to those in
5.2a.

Backward Compatibility with Version 5.0
MESH IMPORTThe method used to automatically partition the boundary of imported meshes in 3D
has been improved. If you have an existing model, you can work with it without being
affected. However, if you click the Import button of the Import feature in the meshing
sequence, the file is read again and the new partitioning method is used. The exception
is if the Import feature had Boundary partitioning set to Manual. In this case, themodified parameter values are preserved under the Feature detection setting, whichuses the same algorithm as in version 5.0.
COMSOL tries to map the old selection on boundaries to the new boundaries, but it
is not always possible to do accurately when new faces have appeared or old faces havedisappeared. You may have to manually review and update boundary, edge, and point
selections after reimporting the mesh.
If you have a Java® or MATLAB® program that imports meshes, the number ofgeometric entities may have changed compared to older versions.
SECURITY SETTINGS

In version 5.2a, the Allow external process and libraries check box on the Security pagein the Preferences dialog box is cleared by default to not allow applications to start
external processes on the computer. The default setting in 5.0 is set to allow suchexternal processes.

COMSOL MULTIPHYSICS|

39

DISPLAY OF MAX/MIN MARKERS IN PLOTS

The display of max/min markers in plots is now off by default to make plots fit better
when using a small graphics canvas. In previous versions, the display of max/min
markers in plots was on by default.
MERGED MPH-FILE FORMATThe MPHAPP file and MPH file formats have been merged since version 5.1, and allapplication files use the .mph file suffix. You can still open MPHAPP files created inversion 5.0.

40 |CHAPTER 1: RELEASE NOTESAC / D C M o dule
New Functionality in Version 5.5
ELECTRIC CURRENTS IN SHELLS AND LAYERED SHELLSThe new AC/DC interfaces, Electric Currents in Shells and Electric Currents in
Layered Shells, are an evolution of the Electric Currents, Layered Shell interface
released in version 5.4 and the older Electric Currents, Shell interface. They provide
improved usability and robustness. Modeling of both nonlayered shells, as well as
layered shells has become more streamlined, and integration with other physics has
been improved. These new AC/DC interfaces only differ in the default settings andcan be used interchangeably, so in reality, it is one interface with two entry points.
When the interface is used for layered shell modeling, the equations are solved in a
product space spanned by the shell’s boundary selection in 3D and an extra dimensionthat points in the shell’s normal direction. This accounts for both tangential andnormal electric fields in the shell. In this state, the interface can model conductors aswell as dielectrics. It supports Stationary, Frequency Domain, and Time Dependentstudies. Together with the MEMS Module or Structural Mechanics Module and the
add-on Composite Materials Module, this allows for modeling piezoelectric materials
in layered shells. For modeling layered shells, the interface replaces the Electric
Currents, Layered Shell interface released in version 5.4.
When used for nonlayered shells, only tangential electric fields are accounted for. It
then replaces the old Electric Currents, Shell interface, except for piezoresistivemodeling. The old Electric Currents, Shell interface has been renamed Electric
Currents, Single Layer Shell and is available in the Model Wizard and Add Physics
dialog under: AC/DC>Electromagnetics and Mechanics>Piezoresistivity.
For backward compatibility, models created in the old physics interfaces will open
using legacy versions of the same old physics interfaces.
MULTIPHYSICS COUPLING FOR ELECTRO-ACOUSTIC TRANSDUCERS

The new Lorentz Coupling feature supports a two-way coupling between the
Magnetic Fields physics interface and the Solid Mechanics interface. The Lorentz force
is determined by computing the cross product of J and B in the volume of the domain.
This force is then applied on the mechanics side as a volumetric force. At the same

AC/DC MODULE|

41

time, the velocity is taken from Solid Mechanics and applied in the Magnetic Fields
interface as a Lorentz velocity term.
The feature is intended for conductive, nonmagnetizable domains (typically, copper
coils). Together with the Acoustic-Structure Boundary multiphysics coupling, thisallows for modeling electro-acoustic transducers. It is available in 2D and 3D for Time
Dependent, Frequency Domain (Perturbation), and Eigenfrequency analysis andrequires the AC/DC Module together with one of these modules: Structural
Mechanics, Acoustics, or MEMS.
NEW AC/DC MODEL WIZARD TREE

The physics interfaces in the AC/DC branch of the Model Wizard tree have beenreorganized to allow for easier navigation. Important multiphysics interfaces thatinvolve the AC/DC Module have been included as well.
EASIER MODELING OF PERMANENT MAGNETS

About 50 sintered NdFeB grades (adhering to the Chinese standard) have been added
to the AC/DC material library. The materials include N, M, H, SH, UH, EH, and TH
grades, and are characterized by typical values for the remanent magnetic flux density
norm and the recoil permeability.
The remanent flux density constitutive relation has been updated to support these newmaterials. The magnitude of the remanent flux density is provided by the material,
while the direction is specified in the physics settings. This allows for quick and easymodeling of devices with permanent magnets. By combining the materials together
with a Material Switch feature, you can sweep over different grades to investigate thecorresponding performance. A number of models in the AC/DC Module Application
Library have been updated to use the new materials.
MATERIAL MODEL IMPROVEMENTS

The user interface and section naming of the material models have been improved andmade more consistent across all interfaces within the AC/DC Module, see alsoprevious section.
IMPROVED B-H CURVES IN NONLINEAR MAGNETIC MATERIALS

A new utility application, the B-H Curve Checker, is available for investigating thequality, smoothness, and physical correctness of nonlinear magnetic B-H curves.
Imported data can be corrected and exported for use in a numerical model. The
methods in the application have been applied to the built-in materials out of which 35

42 |CHAPTER 1: RELEASE NOTES

were optimized for increased performance and stability. The list of corrected materials
follows.

AC/DC• Soft Iron (Without Losses), B-H curve and Effective B-H curve• Soft Iron (With Losses), B-H curve and Effective B-H curve• Nonlinear Permanent Magnet, B-H curve.

Nonlinear Magnetic• Silicon Steel NGO 35JN200• Silicon Steel NGO 35PN210• Silicon Steel NGO 35PN230• Silicon Steel NGO 35PN250• Silicon Steel NGO 50PN1300• Silicon Steel NGO 50PN600• Silicon Steel NGO 50PN700• Silicon Steel NGO 50PN800• Silicon Steel NGO M-22
• Silicon Steel GO 3%• Silicon Steel GO 3413
• Silicon Steel GO 3423
• Silicon Steel GO Silectron 4 mil cross• Silicon Steel GO Silectron 4 mil rolling• Metglas Nano Finemet 50 Hz NoFieldAnnealed• Cobalt Steel Vacoflux 50• Nickel Steel 4750
• Nickel Steel Monimax Nonoriented• Nickel Steel Mumetal 80% Ni• Nickel Steel Square 50• Nickel Steel Superperm 49• Low Carbon Steel 50H470• Low Carbon Steel Magnetite• Low Carbon Steel Soft Iron

AC/DC MODULE|

43

• Low Carbon Steel Vacofer S1 Pure Iron
• Alloy Powder Core Hiflux 125 mu• Alloy Powder Core Hiflux 160mu• Alloy Powder Core Koolmu 125 mu• Alloy Powder Core Koolmu 40 mu• Alloy Powder Core Koolmu 75 mu• Alloy Powder Core Koolmu 90 mu• Alloy Powder Core MPP 60 mu
Note that materials added to a model prior to version 5.5 are not affected unlessreloaded from the material library.
MAGNETOSTRICTIVE MATERIAL WITH HYSTERESISThe nonlinear magnetostrictive material model has been extended to include the Jiles–
Atherton model for magnetic hysteresis. The model is suitable for investigating thehysteretic loss effects in, for example, power transformers and electric machines. The
model parameters are related to microscopic physical effects in magnetic materials, andthey can also be estimated based on experimental data. Magnetostrictive modeling is
supported by the AC/DC Module together with one of these modules: the Structural
Mechanics Module, MEMS Module, or Acoustics Module.
PARAMETRIC HYSTERESISThe Jiles–Atherton model for magnetic hysteresis has been extended to support
parametric stationary studies in addition to the previously available time-dependent
analysis. Ferromagnetic hysteresis is for low-to-moderate frequencies rate-independentand can be analyzed using a parametric stationary study, for example, when studying
magnetization and demagnetization.
SMALL IMPROVEMENTS

A number of smaller improvements and fixes have been implemented.
• The Effective Nonlinear Magnetic Curves Calculator application will now generate
a curve where the saturation region has a differential relative permeability equal tounity.
• The Transition Boundary Condition now allows for adding explicit surface current
density contributions on the up and down sides via a subfeature.
• Support for spatially dependent conductivity has been added to the domain Coilfeature when operated in single conductor mode.

44 |CHAPTER 1: RELEASE NOTES• The Gauge fixing feature has added support for using a magnetostatic
approximation (with Coulomb gauge) in nonconducting domains for Frequency
Domain and Time Dependent studies.
• The solver suggestions for nonlinear time-dependent models have been improved(for the Magnetic Fields interface, together with Time Dependent studies).
• The accurate coil voltage calculation is now available for the Time Dependent study
and has been made available also for boundary coils (Frequency Domain and Time
Dependent studies).
• The method to calculate the coil length for a circular coil has been improved withvolumetric averaging for computing the coil length. It is no longer necessary to
select a set of edges with the correct average length; only the edge directions matter.
• The Contact Impedance feature has been corrected with respect to frequency
domain losses.
UPDATES TO THE AC/DC APPLICATION LIBRARY

In addition to the new B-H Curve Checker application and the updated Effective
Nonlinear Magnetic Curves Calculator application covered in previous sections, thefollowing entries have been updated or are entirely new:
• E-Core Transformer• Electrodynamics of a Power Switch• Electromagnetic Forces on Parallel Current-Carrying Wires• Frequency Domain Study of Three-Phase Motor• Heating Circuit• Induction Heating of a Steel Billet• Inductor in an Amplifier Circuit• Magnet Falling Through Copper Tube
• Magnetic Damping of Vibrating Conducting Solids(New Lorentz Coupling feature)• Magnetic Signature of a Submarine• Pacemaker Electrode• Permanent Magnet• Permanent Magnet Motor in 3D• Piezoelectricity in a Layered Shell (New)• Planar PCB Coil

AC/DC MODULE|

45• Small-Signal Analysis of an Inductor• Solid Multilayer Shell Comparison• Topology Optimization of a Magnetic Circuit• Touchscreen Simulator

Backward Compatibility with Version 5.4 and Earlier
REMANENT FLUX DENSITY MATERIAL PROPERTY GROUP

With the introduction of the remanent flux density material property group, support
for the remanent flux density constitutive relation with the relative permeability given
by an effective medium has been dropped. In other words, a linear (hard) magnetic
material where Br is set and μr given by an Effective medium is no longer supported.
User-defined expressions for μr are still possible and may serve as a substitute.
REFACTORING OF MODEL INPUTS

For all AC/DC Module interfaces, some model input functionality has been moved to
the Default Model Inputs node.
For a temperature-dependent boundary material used in an Impedance boundary
condition, for example, this means the default model inputs should be used, rather
than the feature’s model input section (the model input section in the Impedanceboundary condition’s Settings window).
For more frequently occurring combinations, like a temperature-dependent domainmaterial and a current conservation law, both the default model inputs as well as thefeature’s model input section are available as a means of specifying the temperature.

Backward Compatibility with Version 5.2 and Earlier
COIL FEATURES

Multi-Turn Coil features in old models will be mapped to the new Coil feature using the

Homogenized Multi-Turn Conductor model. Single-Turn Coil features in old models
will import as is with a warning that the feature is obsolete and will be removed infuture versions.
The User Defined Coil Geometry subnode, which is available for 3D Coil nodes with theUser-Defined Coil type, is now a domain feature. You can now select coil input and46 |CHAPTER 1: RELEASE NOTES

output boundaries using the new Input and Output subnodes. The selection is set up
correctly when opening old models.
REMOVED THE OLD INFINITE ELEMENTS FEATURESThe old Infinite Elements feature, which are obsolete since version 4.2, have now been
discontinued and will be automatically removed when opening old models.

Backward Compatibility with Version 5.0 and Earlier
COIL CURRENT CALCULATION

When models saved in previous versions are opened in version 5.1, the Coil Current
Calculation study steps are migrated to Coil Geometry Analysis. Old solutions stored
in the model can still be postprocessed, and the solver sequence will be regenerated
automatically (with a Stationary solver) the first time the study is solved.
The Coil Geometry Analysis study step (formerly Coil Current Calculation) will now
solve for all of the coils in the active interfaces. To solve only for specific coils (specified
using the CoilName property), set the SpecifyCoil property to 1.
The default solver sequence generated by the Coil Geometry Analysis is different inversion 5.1. Code that accesses specific solver features in the generated solver sequence
may need to be reviewed.
OTHER COIL IMPROVEMENTS

Harmonic Perturbation subnodes under coil features (Single-Turn Coil, Multi-Turn Coil)are now global features, so the call to the create method should use the appropriate
space dimension (-1):
model.physics("mf").feature("stcd1").create("hp1","CoilHarmonicPerturbation", -1);

Global features have no selections, so code that accesses the selection of the Harmonic
Perturbation features may need to be reviewed.
Some of the improvements in the 3D Multi-Turn Coil features may require a review ofexisting code that uses the COMSOL API.
Subnodes required to set up the coil features are now added automatically. Existingcode that uses the coil features may need to be updated.
The parameters eCoil and length have been moved from the Multi-Turn Coil features(boundary and domain) to the new subfeature UserDefinedCoilGeometry.

AC/DC MODULE|

47

OTHER IMPROVEMENTS

New functionality introduced in version 5.1 is disabled by default when opening
models created in previous versions:• New boundary conditions for Gauge Fixing features• Accurate coil voltage calculation
This functionality can be enabled using the appropriate inputs in the Settings window.
Refer to the documentation for the individual features for more details.

48 |CHAPTER 1: RELEASE NOTESAcoustics Module
New Functionality in Version 5.5
NEW ELASTIC WAVES, TIME EXPLICIT PHYSICS INTERFACEThe new Elastic Waves, Time Explicit physics interface is based on the discontinuous
Galerkin time explicit method and enables efficient multicore computations of elastic
wave propagation in solids. The interface supports realistic material data such as
anisotropy and damping. The interface is suited for modeling ultrasound propagation
in solids like transducers and sensors, or in nondestructive testing (NDT) applications.
The interface is not limited to ultrasound simulation but applies to any acousticallylarge system that involves the transient propagation over many wavelengths. This also
includes seismic wave propagation in soil and rock.
Acoustic structure interaction (ASI) is modeled by combining the new elastic waves
interface with the Pressure Acoustics, Time Explicit interface and the Acoustic-Structure
Boundary, Time Explicit multiphysics coupling. For geometry assemblies, the Pair
Acoustic-Structure Boundary, Time Explicit can be used.
MULTIPHYSICS FOR ACOUSTIC-STRUCTURE INTERACTION WITH THE
TIME EXPLICIT INTERFACES

For modeling large acoustic structure interaction (ASI) problems using the time
explicit method, the new Acoustic-Structure Boundary, Time Explicit multiphysics
coupling has been introduced. The new feature couples the Pressure Acoustics, Time
Explicit and the new Elastic Waves, Time Explicit physics interfaces. The AcousticStructure Interaction, Time Explicit multiphysics interface adds the two physics and themultiphysics coupling. For taking full advantage of the time explicit formulation, theuse of nonconforming meshes is essential when coupling domains with different
properties. This is achieved by using the new Pair Acoustic-Structure Boundary, Time
Explicit multiphysics coupling that handles geometric assemblies. The use ofnonconforming meshes is a natural extension and use of the properties of the
discontinuous elements.
MATERIAL DISCONTINUITY, PAIR CONDITIONS, AND ATTENUATION FOR
THE ACOUSTIC TIME EXPLICIT INTERFACES

The existing interfaces of the Acoustics Module that are based on the discontinuous
Galerkin (dG) time explicit method now all have the option to include dissipation.

ACOUSTICS MODULE|

49

Dissipation plays an important role when modeling high-frequency applications likeultrasound imaging and flowmeters. The new option exists for the Pressure Acoustics,
Time Explicit interface and the Convected Wave Equation, Time Explicit interface.
In Pressure Acoustics, Time Explicit, the Fluid model list now includes:• Linear elastic• Viscous• Thermally conducting• Thermally conducting and viscous• General dissipation• Ideal gas
In Convected Wave Equation, Time Explicit, the Fluid model list now includes:• Linear elastic• General dissipation
The Pressure Acoustics, Time Explicit interface has been improved with the addition of
a Material Discontinuity (interior) boundary condition and a Continuity pair feature.
Both are used to handle jumps in material properties for either a union with aconforming mesh or an assembly using a nonconforming mesh, respectively.
PORTS FOR THERMOVISCOUS ACOUSTICS

A new Port boundary condition has been added to the Thermoviscous Acoustics,
Frequency Domain interface. It is used to excite and absorb acoustic waves that enter orleave waveguide structures in microacoustics applications. The condition is essential toprovide the full acoustic description at a waveguide inlet/outlet in a mathematicallyconsistent manner, including the viscous and thermal boundary layers. The port
conditions provide a near-perfect, nonreflecting radiation condition for waveguides. In
many cases, using the new Port condition provides superior ease of use and accuracy
compared to an Impedance condition or a perfectly matched layer (PML)
configuration. When working with small acoustic subsystems, two Port conditions areused and combined to automatically compute the scattering matrix, transfer matrix,
and impedance matrix relating the inlet to the outlet. These are all simplified lumped
representations of the subsystem typically used for full system analysis.
UPDATES FOR THE PORT FEATURE IN PRESSURE ACOUSTICS

The Port condition is now also available in 2D for the Pressure Acoustics, Frequency
Domain interface. The condition has a User defined option and a Slit option to define

50 |CHAPTER 1: RELEASE NOTESthe mode shapes. In general, when a port sweep is performed and two ports are used,
one at the inlet and one at the outlet, the transfer matrix and the impedance matrix ofthe system is automatically computed. New transmission loss variables are also set up,
systematically relating two or more ports together. The port sweep functionality now
also works when an inner sweep is performed over the port number.
BACKGROUND FLUID FLOW COUPLING AND MAPPING STUDY FOR
AEROACOUSTICS

A new Background Fluid Flow Coupling multiphysics coupling and a dedicated Mapping
study now automate and simplify the coupling of a CFD model and a convected
acoustic model, including the linearized Navier-Stokes, linearized Euler, andConvected Wave Equation physics. The multiphysics coupling and mapping ensurethat the computed CFD solution is correctly mapped from the fluid flow mesh to theacoustics mesh while also taking care of different discretization orders. The mappingand interpolation is essential in order not to introduce numerical noise into theacoustics model, where the reactive terms are especially important to treat correctly.
ANISOTROPIC MATERIAL FEATURE IN PRESSURE ACOUSTICS

The new Anisotropic Acoustics feature in Pressure Acoustics now makes it possible todefine fluids with an effective anisotropic density and a scale effective bulk modulus.
This makes it possible to set up homogenized material properties for metamaterials orfor defining effective fluid properties of porous and fibrous materials that haveanisotropic structures. The effective density can be defined as having an Isotropic,
Diagonal, or Symmetric structure.
MULTIPHYSICS COUPLING FOR MODELING ELECTROACOUSTIC
TRANSDUCERS (LORENTZ COUPLING)

The Lorentz Coupling feature supports a two-way coupling between the Magnetic Fields
physics interface and the Solid Mechanics interface. The Lorentz force is determined bycomputing the cross product of J and B in the volume of the domain. This force is thenapplied on the mechanics side as a volumetric force. At the same time, the velocity istaken from Solid Mechanics and applied in the Magnetic Fields interface, as a Lorentz
velocity term. The feature automatically handles the frames and moving mesh effects.
The feature is intended for conductive, nonmagnetizable domains (typically, copper
coils). Together with the Acoustic-Structure Boundary multiphysics coupling, thisallows for modeling electro-acoustic transducers. It is available in 2D, 2D axisymmetry,and 3D for Time Dependent, Frequency Domain (Perturbation), and Eigenfrequency

ACOUSTICS MODULE|

51

analysis. The Lorentz Coupling feature requires the AC/DC Module but it is highly
relevant for modeling dynamic loudspeakers.
ACOUSTIC-PIPE ACOUSTIC CONNECTION MULTIPHYSICS COUPLING

The new Acoustic-Pipe Acoustic Connection multiphysics coupling allows coupling a
Pressure Acoustics interface to the Pipe Acoustics interface in both frequency- and timedomain simulations. The coupling is defined between a point in the pipe interface anda boundary in the pressure acoustics interface.
ACOUSTIC-STRUCTURE COUPLINGS FOR LAYERED SHELLS

The multiphysics couplings between acoustics and structures have been extended tosupport the Layered Shell physics interface. This allows modeling of vibroacoustic
problems involving composite materials and other layered structures. The Layered
Shell interface is now supported for the following multiphysics couplings:• Acoustic-Structure Boundary• Thermoviscous Acoustic-Structure Boundary• Aeroacoustic-Structure Boundary• Porous-Structure Boundary
NEW ACOUSTOPHORETIC RADIATION FORCE

A new and updated Acoustophoretic Radiation Force feature (replacing the
Acoustoforetic Force feature) includes formulations of the radiation force that acts on
acoustically small solid particles and liquid drops; that is, particles and drops studied in
the Rayleigh limit. New formulations of the force expressions can be selected for verysmall drops and particles that are comparable to or smaller than the viscous andthermal acoustic boundary layers (the thermal and viscous penetration depth). The
feature can be combined with both Pressure Acoustics and Thermoviscous Acoustics tomodel particle sorting and other acoustofluidic applications. This feature requires theParticle Tracing Module.
IMPROVEMENTS TO ITERATIVE SOLVER SUGGESTIONS IN ACOUSTICS

The default generated solver suggestions for models that include one or moreinterfaces from the Acoustics Module and multiphysics couplings have been further
improved. The handling for multiple acoustics interfaces and multiphysics couplings
now includes the following functionality:• Common iterative solver suggestions are now set up by the Acoustic BEM-FEM
Boundary, the Acoustic-Structure Boundary, the Thermoviscous Acoustic-

52 |CHAPTER 1: RELEASE NOTESStructure Boundary, the Acoustic-Thermoviscous Acoustic Boundary, theAeroacoustic-Structure Boundary, the Piezoelectric Coupling, and the Solid-Shell
Connection.
• Lagrange multiplier variables are handled correctly by the Vanka preconditioner
when necessary.
Other default and solver suggestion improvements include:• An iterative solver suggestion for the Compressible Potential Flow interface.
• New Stationary-Frequency and Stationary-Transient solver configuration whencoupling Compressible Potential Flow and Linearized Potential Flow in a convected
acoustics simulation.
• A second iterative solver suggestion is now added for models that couples Pressure
Acoustics to Solid Mechanics with the Acoustic-Structure Boundary multiphysics
coupling.
• A better default solver has been added when using the Linearized Euler interfaces.
NEWS SOLVERS FOR LARGE ACOUSTIC PROBLEMS

Two new specialized iterative solver methods have been introduced for frequencydomain simulations modeled with the Pressure Acoustics, Frequency Domain interface;that is, large scalar Helmholtz problems (when measured on the number ofwavelengths) based on the finite element method. The new solvers can be used toanalyze enclosed volumes such as that of a car cabin interior as well as other acoustics
simulations. The domain decomposition (DD) method supports the use of absorbing
boundary conditions for the domain boundaries. This is important for clustercomputation using DD for Helmholtz problems. Secondly, the complex shifted
Laplacian technique can be used for both the normal multigrid preconditioner as wellas the DD method. The multigrid alternative is the best option for large problems
when not using a cluster. With version 5.5, you can solve significantly larger problems
in acoustics than before. For example, a car cabin interior acoustics model can now besolved up to 7 kHz (solving 83.5 million DOFs using 105 GB of RAM), whereas it
would only converge up to about 3 kHz in earlier versions. This corresponds to solving
a one-order-of-magnitude larger problem.
RESTRUCTURE OF THE MODEL WIZARD TREE AND APPLICATIONLIBRARY

With the introduction of the new Elastic Waves, Time Explicit interface, the physics
interface locations in the Model Wizard tree have been updated with two newbranches: Elastic Waves and Pipe Acoustics.

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To get a better overview of the existing and many new tutorial models, the Application
Library has also been updated with following new categories:• Elastic Waves• Tutorials, Pressure Acoustics• Tutorials, Pipe Acoustics• Tutorials, Thermoviscous Acoustics.
IMPORTANT ENHANCEMENTS IN THE ACOUSTICS MODULE• In the Exterior Field Calculation feature, the infinite symmetry and antisymmetry
planes can now be moved (offset) by assigning the location of the symmetry plane.
• The Octave Band plots now also have the option to use 1/6 octaves.
• The reference direction can now be set in 1D Radiation Pattern plots of 2D models• The Directivity plot now comes with a true logarithmic axis. The plot has been
moved to 1D plot groups.
• Exclude Edges and Exclude Points option have been added for all constraint-typeboundary conditions (Dirichlet conditions) in Thermoviscous Acoustics, Linearized
Navier-Stokes, and Linearized Euler interfaces. This option allows to handle overconstrained problems and simplify certain combinations of boundary conditions.
This new options is available when the View Advanced Physics option is selected.
• The Rayleigh unit, rayl, used for the specific acoustic impedance is available in boththe SI unit and the CGS unit version. They are named [rayl] and [rayls_cgs],
respectively.
• Surface stress variables now exist on both exterior and interior boundaries in the
Thermoviscous Acoustics and Linearized Navier-Stokes physics interfaces.
• A new Absorption Coefficient option in the Impedance boundary condition in
Pressure Acoustics. This new option simplifies the input of certain measured surface
impedance data, and it is especially useful in the higher frequency ranges where theimpedance phase becomes less important for accurate simulation results.
• The Characteristic specific impedance condition in Pressure Acoustics now works forwaves propagating at a given angle toward the boundary.

54 |CHAPTER 1: RELEASE NOTESNEWS IN RAY ACOUSTICS

Several enhancements and new features have been introduced in the The Ray Acoustics
interface.
• When you release rays from a grid of points using the Release from Grid feature, you
can now preview the initial ray positions in the Graphics window. In the Initial
Coordinates section of the Settings window, click the Preview Initial Coordinates
button to view the initial ray coordinates as a grid of points. Click the Preview Initial
Extents button to view the spatial extents of the initial coordinates as a boundingbox. These buttons allow you to check the initial ray positions before running a
study.
• When you release rays in a cone, a new type of Conical distribution is available,
Hexapolar. For the hexapolar cone type, rays are released at uniformly distributed
angles from the cone axis, with each ring having six more rays than the previous one.
• You can now select Isotropic scattering as the wall condition when rays hit surfaces
in the geometry. Like the Diffuse scattering condition, the Isotropic scattering
condition causes rays to be reflected with randomly sampled directions around thesurface normal. However, whereas the Diffuse scattering condition uses a probability
distribution based on the cosine law, the Isotropic scattering condition follows aprobability distribution that gives equal flux across any differential solid angle in thehemisphere.

New and Updated Model Examples in 5.5• The Sound Transmission Loss through a Concrete Wall model presents a practicaland efficient method to compute the sound transmission loss (STL) through abuilding component.
• The Headphone on Artificial Ear model shows how to model the coupling of acircumaural headphone to a generic artificial ear. The model uses the Poroelastic
Waves physics interface to model the foam. The built-in Interior Perforated Plate
model is used to represent perforates and meshes in the headphone casing.
• The OW Microspeaker: Simulation and Correlation to Measurements model
analyzes the electromagnetic, mechanical, and acoustical characteristics of the OWS1943T-8CP (discontinued) speaker. Beside certain details, the geometry, material
properties, and measurements are copyrighted by Ole Wolff. Starting from thegeometry of the speaker, an axisymmetric electromagnetic model is used tocharacterize the frequency-dependent response of the voice coil and

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electromagnetic circuit. This response is included in a 3D model where thevibroacoustic response of the speaker is analyzed and compared with measurements.
• The Wax Guard Acoustics: Transfer Matrix Computation tutorial is set up to
analyze the acoustic properties of a wax guard. A wax guard is a small perforated
mesh used to protect the receiver (the miniature loudspeaker in a hearing aid) used
for hearing aids. Because of the very small dimensions of the structure, the thermaland viscous boundary layer losses need to be included in detail, and therefore theThermoviscous Acoustics, Frequency Domain interface is used. The transfer matrix(or two-port) of the wax guard is computed using the Port Sweep functionality and
the Port boundary condition.
• The Head and Torso HRTF Computation tutorial model shows how to import a
3D scanned geometry of a human head and torso and compute the head-relatedtransfer function (HRTF). The scan is imported as an STL file and converted into a
COMSOL geometry. The HRTF is computed using the reciprocity principle andthe BEM method.
• The Shape Optimization of an Acoustic Demultiplexer model shows how shape
optimization can be used to design an acoustic demultiplexer. A demultiplexer is adata distributing device; in this case, it will distribute acoustic energy.
• In the Ground Motion After Seismic Event: Scattering off a Small Mountaintutorial, the propagation of elastic waves in the ground after a seismic event issimulated using a 2D model and the Elastic Waves, Time Explicit interface.
• In the Isotropic-Anisotropic Sample: Elastic Wave Propagation tutorial, a test
sample consists on one side of an isotropic material and on the other side of aheterogeneous anisotropic material (a transverse anisotropic zinc crystal). Elastic
waves in the sample are excited by a point-like force. The model is solved with the
Elastic Waves, Time Explicit physics interface.
• The Acoustics of a Pipe System with 3D Bend and Junction tutorial shows how tomodel the propagation of acoustic waves in large pipe systems by coupling the Pipe
Acoustics interface to the Pressure Acoustics interface using the Acoustic-Pipe
Acoustics Coupling multiphysics feature. The tutorial is set up in both the time andfrequency domain.
• The Spherical Scatterer: BEM Benchmark tutorial is a classical BEM benchmark
model. A spherical scatterer is placed in a plane wave background field. When thesphere is modeled as sound hard, the problem has an analytical solution. The modelcompares the results using the Pressure Acoustics, Boundary Elements interface withthe analytical solution for several frequencies. The results show very good
agreement. The model results do not show any irregular modes.

56 |CHAPTER 1: RELEASE NOTES• The Acoustic Cloaking model has been updated to use the new Anisotropic Acoustics
feature to model the metamaterial used to cloak the sphere.
• The Optimizing the Shape of a Horn model has been updated to use the new builtin shape optimization functionality.

Backward Compatibility with Version 5.4
For the Pressure Acoustics interfaces, the following features have been removed fromthe Fallback feature submenu to the Pair features: Matched Boundary, Exterior Field
Calculation, Port, Plane Wave Radiation, Circular Wave Radiation, and Spherical Wave
Radiation.

Backward Compatibility with Version 5.3a
For the Linearized Navier-Stokes interfaces, the override rules for boundary
conditions have changed. To obtain the old behavior of a model, disable the boundary
conditions that should not contribute to the solution.

Backward Compatibility with Version 5.3
For the Linearized Euler, Transient interface, initial conditions are only used for the
dependent variables. The initial conditions for the time derivatives have therefore been
removed. For a model with fields rho, u, and p, remove the Java® lines setting
drho/dt, du/dt, and dp/dt (these parameters change names when the field names
change).

Backward Compatibility with Version 5.2
The default settings have changed for the Incident Pressure Field in the Pressure
Acoustics interfaces. Add the following line to obtain the old behavior of this featurewhen ipf1 is a subfeature to pwr1:
model.physics("acpr").feature("pwr1").feature("ipf1").
set("c", "acpr.c_c");

Backward Compatibility with Version 5.1• Plane Wave Radiation has been removed from the Linearized Potential Flow,
Frequency Domain and Linearized Potential Flow, Transient interfaces in 1D
axisymmetry.

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• A new Lagrange multiplier variable (ta.lm_slip) has been added to the slip
conditions in the Thermoacoustics, Frequency Domain interface. If you run amodel with a segregated solver, you will need to add this variable to the groupcontaining the velocity degree of freedom. You can also regenerate the default
solver. In the API, you need to add comp1_ta_lm_slip to the declaration of thesegregated step; for example, adding:model.sol("sol1").feature("s1").feature("se1").feature("ss1").
set("segvar", new String[]{"comp1_p", "comp1_u", "comp1_T","comp1_ta_lm_slip"});• The Waveguide end impedance option has been removed from 2D, 1D
axisymmetric, and 1D as it had no physical meaning in these space dimensions.

58 |CHAPTER 1: RELEASE NOTESBatteries & Fuel Cells Module
New Functionality in Version 5.5• A new charge balance model, “Single-ion conductor”, has been added to the
Lithium-Ion Battery interface. A new Model Wizard entry, “Lithium-Ion Battery,Single-Ion Conductor”, which uses the Single-Ion Conductor charge balance
model by default, has been added to the Model Wizard.
• New Thin Electrolyte Layer node available in the Lithium-Ion Battery interface.
The node is available when the Single-Ion conductor charge balance model has been
selected.
• Added support for including convective contribution, with a specified velocity, tothe electrolyte concentration mass balance equation in the Lithium-Ion Battery andBattery with Binary Electrolyte interfaces.
• An overhaul has been done for the lithium insertion and lithium metal kinetics inthe Lithium-Ion Battery and Single Particle Battery interfaces.
• In the Particle Intercalation node, the Number of elements setting under Particle
Discretization now supports input from Parameters.
• The Batteries & Fuel Cells material library has been updated with individual
literature references for each material property.
• The Lumped Battery interface now includes three new operation modes:
Potentiostatic, Power, and Circuit Voltage Source.
• The Lumped Battery interface now includes a Short Circuit node.
• New User defined and From definitions options are now available in the Cell
Equilibrium Potential node in the Lumped Battery interface and Battery Equivalent
Circuit Model Wizard entry (the Battery Open Circuit Voltage node in the Electric
Circuit interface) for defining the equilibrium potential and the temperature
derivative of the potential.
• An RC circuit element has been added to the Electrical Circuit interface. The RC
element has also been added to the Battery Equivalent Circuit Model Wizard entry.
• The Thermodynamics node has been added to the Batteries & Fuel Cells Module
license.
• The Mass flow boundary condition option in the Inlet feature in the Single Phase
Flow interface has been added to the Batteries & Fuel Cells Module license.

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• A new Mass flow rates option has been added to the Inflow node of the Transport ofConcentrated Species interface.
• Partial pressure variables have been added to the Transport of Concentrated Species
interface, when Ideal gas is selected as the mixture density. This facilitates setting up
fuel cell models, especially when using the Nernst Equation option for theequilibrium potential.
• A new Nernst Equation option is now available for defining the equilibrium potential
in the Electrode Reactions and Porous Electrode Reaction nodes. In the Tertiary
Current Distribution, Nernst-Planck interface, the concentration dependence of theequilibrium potential for the Nernst Equation option is defined automatically basedon the reaction stoichiometry.
• The exchange current density for the Butler-Volmer and Linearized Butler-Volmer
kinetics options in the Electrode Reaction and Porous Electrode Reaction nodes can
now be made automatically concentration dependent. The option is available if the
Nernst-Equation option is used when defining the equilibrium potential. In the
Tertiary Current Distribution, Nernst-Planck interface, the options Mass action law
and Lumped multistep are available for the exchange current density type.
• The Tertiary Current Distribution, Nernst-Planck interfaces have changed default
settings to use the Nernst equation option for the equilibrium potential, ButlerVolmer for the kinetics expression type, and Mass action law for the exchange current
density type.
• The Electroanalysis (elan) interface has been replaced with the new Electroanalysis(tcd) entry in the Model Wizard. The new Electroanalysis (tcd) interface provides
seamless switching between the various charge conservation model options
supported by the Tertiary Current Distribution, Nernst-Planck interface.
• The Chemistry interface, added to the Electrochemistry Module in version 5.5, now
supports Electrode Reactions and Electrode Reaction Groups. The Chemistryinterface allows for defining multiple species and electrode reactions, as well as
ordinary chemical reactions. Also, mixture and thermodynamic properties, such as
equilibrium potentials, can be calculated automatically by the Chemistry interface.
Variables defined by these features can then be used in any physics interface.
• The Non-Faradaic Reactions nodes now also allow to set reaction rates for the bulk
species in the electrolyte.
• The Common model input has been set as the new default for Temperature model
input in all electrochemistry interfaces.

60 |CHAPTER 1: RELEASE NOTES• The Cyclic Voltammetry boundary condition at the Electrode Surface node andCyclic Voltammetry study step is now available for all Electrochemistry interfaces.
• The Thin Electrode Surface node is now also available in the Primary Current
Distribution interface.
• New and updated default plots have been added in the Transport of Diluted Species,
Tertiary Current Distribution, Nernst Planck, and Darcy’s Law interfaces.
• A new mass inflow boundary condition has been added to Darcy’s Law.
• The extended Inlet/Outlet boundary condition in the Darcy’s Law interface now
includes Velocity (Inlet/Outlet), Pressure (Inlet/Outlet) and Mass flow (Inlet)
options.
• The Darcy’s Law interface now supports Frequency Domain studies (with licenses
for the Batteries & Fuel Cells Module, Corrosion Module, Electrochemistry
Module, and Electrodeposition Module).
• More accurate definitions of the internal cH and pH variables (in basic electrolytes)
and the cOH and pOH variables (in acid electrolytes) in the Tertiary Current
Distribution, Nernst-Planck (water-based charge balance option) andElectrophoretic Transport interfaces have been implemented.
• The implementation of the Donnan boundary conditions used by the Ion-Exchange
Membrane node has been improved.
• A new boundary condition formulation option has been added in the Film Resistancesection of the Electrode Surface, Internal Electrode Surface, and Thin Electrode Surface
nodes in the Primary Current Distribution interface.
• The default stoichiometric number for Dissolving-Depositing species has beenchanged to 0 (from 1).

New and Updated Applications and Models in Version 5.5• The Parameter Estimation of a Time-Dependent Lumped Battery Model has been
updated to include a third study for load cycle prediction.
• A new Lithium-Ion Battery with Single-Ion Conducting Solid Electrolyte has
been added, which demonstrates the Lithium-Ion Battery, Single-Ion Conductor
interface.
• A new Solid Oxide Electrolyzer model has been added, which demonstrates someof the new functionalities in the Thermodynamics and Chemistry nodes.

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• A new Aging Analysis of a Lumped Battery Model has been added, which
demonstrates the Capacity Loss feature and some of the new operation modes in theLumped Battery interface.
• A new Thermal Distribution in a Pack of Cylindrical Batteries has been added,
demonstrating thermal management modeling using the Lumped Battery interface.
• The following models have been updated to use the new Electroanalysis (tcd)interface: impedance_spectroscopy, microdisk_voltammetry, andcyclic_voltammetry_1d.
• The impedance_spectroscopy, microdisk_voltammetry, cyclic_voltammetry_1d,
ht_pem, pem_mea_1d, fuel_cell_cathode, sofc_unit_cell, orange_battery,
v_flow_battery, pb_flow_battery, and zn_ago_battery_1d models have been
updated to use the new Nernst equation option and concentration-dependentexchange current density in Butler-Volmer kinetics.

Backward Compatibility with Version 5.4• The Java API migration code handling the new lithium insertion and lithium metal
kinetics in the Lithium-Ion Battery interface and the Single Particle Battery
interface assumes that ka=kc and cl_ref have been manually set in Java; if this is
not the case, backward compatibility may be affected.
• The default stoichiometric number for Dissolving-Depositing species has beenchanged to 0 (from 1). Java API backward compatibility may be affected.
• The Tertiary Current Distribution, Nernst-Planck interfaces have changed default
settings to use the Nernst equation option for the equilibrium potential, ButlerVolmer for the kinetics expression type, and Mass action law for the exchange
current density type. Java API backward compatibility may be affected.

62 |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 5.5
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 5.5 includes an upgraded version of the Parasolid kernel. As a result, a
number of stability issues have been fixed, which makes the import of CAD models andsolid operations more robust.
• The CAD file import functionality included with these products has been extended
to support new versions for some of the supported file formats (see under Read from
File, CAD on www.comsol.com/products/specifications/cad).
• The CAD file import functionality now supports associative geometry import toretain physics and other settings on the geometry after the file is imported again.
The import reads information in the CAD files to identify the geometric entities in
the file. This information is usually available when importing CAD files saved in thenative format of the software where it was created.
• The CAD file import functionality now generates selections based on the material
and layer assignments of the geometric objects when this is available in the CAD file.
Selections are also generated for assigned colors to geometric entities. The selections
are available in the appropriate input selection lists of features in the model tree.
• You can use the new Delete Holes defeaturing tool to search for and delete
cylindrical holes smaller then a specified radius.
• Support has been added to export geometry to the STEP and IGES formats.

New Functionality in the Design Module in Version 5.5
The Design Module adds support for geometric constraints and dimensions in 2D
geometry sequences, including in geometry parts and work planes in 3D.

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New Functionality in LiveLink™ for AutoCAD® in Version 5.5• The LiveLink interface now keeps track of the layer state of the synchronized CAD
file, and the same layer state is used for subsequent synchronizations.
• Layer selections, which are generated based on the layer name that the geometricobjects belong to in the CAD file, are now also available as object selections in theappropriate input selection lists of geometry features following the LiveLink™
feature in a geometry sequence.
• The LiveLink™ interface now supports AutoCAD® 2020.

New Functionality in LiveLink™ for Inventor® in Version 5.5• The LiveLink interface now synchronizes the material properties for the parts in the
CAD files. The Material nodes are created in the component of the LiveLink featurein the model, and their selection is set to the selection corresponding to the material.
• The LiveLink™ interface now supports Inventor® 2020.

New Functionality in LiveLink™ for PTC® Creo® Parametric™ in
Version 5.5• The LiveLink interface now synchronizes the material properties for the parts in the
CAD files. Based on the material data, Material nodes are created in the componentof the LiveLink feature, and their selection is set to the selection corresponding to
the material.
• The LiveLink™ interface now supports PTC® Creo® Parametric™ 6.0.
• Support for PTC® Creo® Parametric™ 2.0 is no longer available by the LiveLink™
interface. File import of PTC® Creo® Parametric™ 2.0 continues to be supported.
• Support for PTC® Creo® Parametric™ 3.0 by the LiveLink™ interface will be
removed in the next major release of COMSOL Multiphysics®. File import of PTC®
Creo® Parametric™ 3.0 will continue to be supported.

New Functionality in LiveLink™ for Revit® in Version 5.5• The LiveLink interface now synchronizes the material properties for elements in the
Revit® project. Based on the material data, Material nodes are created in the64 |CHAPTER 1: RELEASE NOTEScomponent of the LiveLink feature, and their selection is set to the selection
corresponding to the material.
• The LiveLink™ interface now supports Revit® 2020.

LiveLink™ for Solid Edge®
NEW FUNCTIONALITY IN VERSION 5.5• The LiveLink interface now synchronizes the material properties for the parts in the
CAD files. Based on the material data, Material nodes are created in the componentof the LiveLink feature, and their selection is set to the selection corresponding to
the material.
• Expanding on the functionality that synchronizes selections based on material
assignments to the CAD design in Solid Edge®, the LiveLink™ interface now adds
support for user-defined selections. In the added COMSOL Selections interface in
Solid Edge®, you can define selections that are synchronized to the COMSOLMultiphysics® model. You can choose to synchronize selections for assemblyfeatures, bodies, faces, or points, which become selections in the model when thedesign is synchronized with the COMSOL Multiphysics® model.
• The LiveLink™ interface now supports Solid Edge® 2020.
BACKWARD COMPATIBILITY WITH VERSION 5.0

The default value for the keepfree property of the LiveLinkSolidEdge function is
now set to on. Previously, the default was set to off.

LiveLink™ for SOLIDWORKS®
NEW FUNCTIONALITY IN VERSION 5.5• The LiveLink interface now synchronizes the material properties for the parts in the
CAD files. Based on the material data, Material nodes are created in the componentof the LiveLink feature, and their selection is set to the selection corresponding to
the material.

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65

Backward Compatibility with Previous Versions
BACKWARD COMPATIBILITY WITH VERSION 5.3A

The new fillholes property has been added for the Import function. The following
applies:• The combination of the fillholes property set to on and the knit property set tosolid is equivalent to the knit property set to solid in previous versions.
• The combination of the fillholes property set to off and the knit property set
to surface is equivalent to the knit property set to surface in version 5.3a.
• The combination of the fillholes property set to on and the knit property set tosurface is equivalent to the knit property set to surface in version 5.3 andprevious versions.
The new fillholes property has been added for the Knit function. The Knit
function with the fillholes property set to on corresponds to the Knit function inprevious versions.
BACKWARD COMPATIBILITY WITH VERSION 5.2

Geometry Repair Tolerances
The geometry repair tolerance can be automatic, relative, or absolute in version 5.2a.
In previous versions, the repair tolerance was always a relative tolerance.
• If you have not set the relative repair tolerance repairtol, you will get the newdefault repair tolerance type: auto. This will result in a valid geometry in almost allcases. In extreme cases, the result can have a different topology than in 5.2.
• In rare cases, if you have set the repairtol tolerance, version 5.2a can fail whenbuilding the geometry. If so, set repairtoltype to auto (select Automatic from theRepair tolerance list) to get the 5.2 behavior.
BACKWARD COMPATIBILITY WITH VERSION 5.0

The default value for the keepfree property of the LiveLinkSOLIDWORKS function
is now set to on. Previously, the default was set to off.

66 |CHAPTER 1: RELEASE NOTES

CFD Module
New Functionality in Version 5.5• The user interface for the Fluid Properties node in the Laminar Flow and Creeping
Flow interfaces has been redesigned. It now contains a new section, Constitutive
relations, with two options, Newtonian and Inelastic non-Newtonian. The first option
contains settings for the dynamic viscosity, whereas the second options contains thepredefined inelastic non-Newtonian models.
• A warning is given by the solver when a model lacks a Pressure Point Constraint nodeand the pressure level is not set in any other boundary condition node.
• Better control over constraints in the Wall boundary feature. Whereas in previous
versions, it was possible to override the default constraints by weak constraints, it is
now also possible to choose between pointwise, discontinuous Galerkin, and mixed
constraints.
• The new physics interface, Viscoelastic Flow, for incompressible, laminar flow of
fluids exhibiting both viscous and elastic behavior has been added under SinglePhase Flow in the Fluid Flow branch. The predefined constitutive models include
Oldroyd-B, Giesekus, and FENE-P.
• New functionality in the Bubbly Flow interfaces includes a new Flow Continuity
pair feature, a new Periodic Flow pair feature, and application of the Boussinesq
approximation to model buoyancy effects in the low-gas-concentration limit.
• New functionality in the Euler-Euler Model interfaces includes an improved Wallboundary feature, which picks up the frame motion by default; a new Interior Wallfeature; a new Flow Continuity pair feature; and a new Mass Transfer domainfeature.
• The laminar Two- and Three-Phase Flow interfaces now support all inelastic nonNewtonian constitutive relations.
• The Two-Phase Flow, Phase Field interface now supports Marangoni effects. The
Phase Field interface also has an improved Continuity pair feature for nonmatchingmeshes.
• A new physics area, Phase Transport Mixture Model, containing physics interfaces
for simulating laminar and turbulent n-phase flow, has been added under Phase
Transport in Multiphase Flow. All RANS turbulence models are supported. The
physical properties of the various phases, and the slip velocity between the dispersed

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phases and the continuous phase, can be specified in the Mixture Model
multiphysics coupling node.
• In the Brinkman Equations and Free and Porous Media Flow interfaces, the Porous
Matrix Properties section in the Fluid and Matrix Properties domain feature now
contains a Non-Darcian option in the drop-down list for the Permeability model. This
option also replaces the old Forchheimer Drag subfeature.
• In the Darcy’s Law interface, the Matrix Properties section in the Fluid and Matrix
Properties domain feature now contains a Non-Darcian option in the drop-down list
for the Permeability model. This can be used to add a Forchheimer drag term to themomentum equation. The Darcy’s Law interface also has a new setting, at theinterface level, for including gravity effects.
• Large Eddy Simulation (LES) interfaces for nonisothermal flow are now available in
the Model Wizard. The three new interfaces, LES RBVM, LES RBVMWV, and LES
Smagorinsky, are all based on variational multiscale methods. Additional subgrid
heat fluxes are added in the Nonisothermal Flow multiphysics coupling node inconsistency with the chosen variational multiscale method (RBVM, RBVMWV, or
Smagorinsky).
• The new physics interface, Compressible Euler Equations, has been added underHigh Mach Number Flow in the Fluid Flow branch. It is applicable to transient,
isentropic flow of ideal gases at transonic and supersonic speeds.

New Model in Version 5.5.
The model Unsteady 3D Flow Past a Cylinder, under Verification Examples in the
Application Library, compares the results for lift and drag coefficients with those foundin literature. Oil-Water Flow Through an Orifice - A Droplet Population Model,
under Multiphase Flow in the Application Library, considers turbulent flow and breakup of five populations (size containers) of droplet size. Two new fluid-structureinteraction models are available with the Structural Mechanics Module: Two-Phase
Flow with Fluid-Structure Interaction models the deformation of a thin plate by alock-release gravity current, and Bimetallic Strip in Air Flow models the deformationof a bimetallic strip by thermal stresses, dynamic pressure, and convective cooling.

Backward Compatibility with Version 5.4 and Earlier
Models created using the Brinkman Equations and Free and Porous Media Flowinterfaces need to be modified if they apply Forchheimer drag. The previous subfeature
has been replaced by a new setting in the Porous Matrix Properties section.

68 |CHAPTER 1: RELEASE NOTESOld Java files need to replace the line
model.component("comp1").physics("fp").feature("fmp1").
create("fd1", "Forchheimer", 2);withmodel.component("comp1").physics("fp").feature("fmp1").
set("ktype", "nonDarcianModel");Forchheimer is the default. Also replacemodel.component("comp1").physics("fp").feature("fmp1").
feature("fd1").set("betaF", "value");withmodel.component("comp1").physics("fp").feature("fmp1").
set("cf", "value");

Backward Compatibility with Version 5.3a
MIXTURE MODEL EQUATION FORMULATIONThe Mixture Model equation formulation has been revised to increase the accuracy
and facilitate the solution of a number of problem setups. As a consequence of therevision, old models can return slightly different results in the new version compared
to previous versions.
EULER-EULER MODEL

The results from models using the Euler-Euler Model interfaces may differ in version
5.5 due to the more general formulation for the viscous stress in the momentum
equation for the dispersed phase. The behavior in the old formulation may be
reproduced by dividing the dispersed phase viscosity, μD, by the variable ee.phidPos.
NO FLUX FORMULATION

The formulation of the No Flux feature has been changed in the Transport of Diluted
Species interface in version 5.4 so that the flux relative to the convective flux is set tozero. The new formulation is used when opening a model from a previous session. In
the previous formulation, the total flux was set to zero.

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FULLY DEVELOPED FLOW REPLACES LAMINAR INFLOW AND LAMINAR
OUTFLOWThe Laminar inflow and Laminar outflow options on Inlets and Outlets, respectively,
have been replaced with the Fully developed flow option. Models built in versions prior
to 5.4 will contain warnings about obsolete functionality.

Backward Compatibility with Version 5.0
TRANSPORT OF CONCENTRATED SPECIESSee Chemical Reaction Engineering Module.

70 |CHAPTER 1: RELEASE NOTESChemical Reaction Engineering
ModuleNew Functionality in Version 5.5• A new Generate Material wizard is available for Thermodynamic System nodes.
• A new Generate Chemistry wizard is available for Thermodynamic System nodes.
• A new thermodynamic model, Water (IAPWS), for steam and water properties as
defined by the International Association for Properties of Water and Steam has been
added.
• New diffusivity models are available in Thermodynamics. Two new properties,
Diffusion coefficient at infinite dilution and Maxwell-Stefan diffusivity, are available
both for gas-phase and liquid-phase systems.
• New equilibrium calculations available in Thermodynamics. Equilibrium
calculations at a specified density, or a specified volume, can now be created.
• A new single-phase property, the Helmholtz energy, is available in the
Thermodynamic System nodes.
• Two new viscosity models for liquids, molar cubic mixing and mass cubic mixing,
are available in the Thermodynamic System nodes.
• Updated default plots for all mass transport interfaces. Plots for all included species
are now generated.
• Extended multiphase support in the Chemistry interface. Surface species and solidphase species are now handled in separate lists in the Species Matching section.
• A new setting to include the convection, is available in the No Flux, Flux, andSymmetry boundary nodes for mass transfer.
- The setting can be used to include the convective contribution in the prescribedflux.
- Affected interfaces: Transport of Diluted Species, Transport of Diluted Species in
Porous Media, Transport of Concentrated Species (only in the Flux node),
Nernst-Planck Equations, and Electrophoretic Transport.
• New adsorption models for mass transport in porous media. The Toth and BET
models are now available in the Adsorption node.

CHEMICAL REACTION ENGINEERING MODULE|

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• Mass flow rates can now be prescribed, per species, in the Inflow feature in theTransport of Concentrated Species interface.
• The mass flow rate can now be prescribed in the Inflow feature in the Darcy’s Law
interface.

Backward Compatibility with Version 5.4 and Earlier
SPECIFYING VOLUMETRIC FLOW RATE OF A PLUG FLOW REACTOR IN
REACTION ENGINEERING

When using the Reaction Engineering interface to model gas flow in a plug flow
reactor, you must now specify either the pressure or the volumetric flow rate, not both.
Running Java® files from previous versions may fail if the volumetric flow rate is set
while also prescribing the pressure. In this case, specify to instead compute the pressure
from the ideal gas law in the following manner:model.component("comp1").physics("re").prop("mixture").set("psource","idealGas");This selects Ideal gas law in the Reactor pressure list in the Mixture Properties section.
When this is done, the User defined option is available in the Volumetric rate list in theMass Balance section.
WALL FUNCTION VARIABLES OMITTED IN LAMINAR REACTING FLOW

Dependent variables for the mass fraction wall functions are no longer added whenusing the Reacting Flow multiphysics interface for laminar flow. Due to the nowomitted variables, running Java® files from previous versions may fail during the solver
sequence generation.
When specifying the content of a segregated group in the manner ofmodel.sol("sol1").feature("s1").feature("se1").feature("ss1").set("segvar", new String[]{"comp1_w1", "comp1_w2", "comp1_tcs_wWall_w1","comp1_tcs_wWall_w2"});

remove entries for the wall functions variables of the kind comp1_tcs_wWall_name toresult inmodel.sol("sol1").feature("s1").feature("se1").feature("ss1").set("segvar", new String[]{"comp1_w1", "comp1_w2"});72 |CHAPTER 1: RELEASE NOTESBackward Compatibility with Version 5.3a and Earlier
NO FLUX FORMULATION

The formulation of the No Flux feature has been changed in the Transport of Diluted
Species interface in version 5.4 so that the flux relative to the convective flux is set tozero. The new formulation is used when opening a model from a previous session. In
the previous formulation, the total flux was set to zero.
Affected interfaces: Transport of Diluted Species, Transport of Diluted Species in
Porous Media, Transport of Concentrated Species, Nernst-Planck Equations, andElectrophoretic Transport.

Backward Compatibility with Version 5.0 and Earlier
REACTION ENGINEERING AND CHEMISTRY INTERFACES

The API syntax for creating surface species has changed. Running Java® files fromprevious versions may fail due to the new default name indexes, including ads forsurface species and s for solids in the Reaction Engineering and Chemistry interfaces.
The surface species names and solid species names need to be changed accordingly in
any Java® code:• Change any species index (s) to (ads)• Change any species index (S) to (s)The following shows an example of the needed code change:
Version 5.0 and earlier:model.physics("re").feature("rch1").set("formula", "A+B(S)=>C+D(s)");model.physics("re").feature("spec1").set("specName", "As(s)");model.physics("chem").feature("rch1").set("formula", "A+B(S)=>C+D(s)");model.physics("chem").feature("spec1").set("specName", "As(s)");Change this to
Version 5.2 and later:model.physics("re").feature("rch1").set("formula", "A+B(s)=>C+D(ads)");model.physics("re").feature("spec1").set("specName", "As(ads)");model.physics("chem").feature("rch1").set("formula", "A+B(s)=>C+D(ads)");model.physics("chem").feature("spec1").set("specName", "As(ads)");CHEMICAL REACTION ENGINEERING MODULE|

73

TRANSPORT OF CONCENTRATED SPECIES INTERFACE

Updated Internal Variable Names
The internal variable names of vector and tensor components have changed in theTransport of Concentrated Species interface. In most cases, users will not be affectedby this change. When opening a model file created in a previous version, the previous
variable definitions remain. However, when updating or recomputing the solution,
new variable names will be generated. This means that if any of these variable names
have been used in a user-defined expression or plot, they need to be updated manually
as described below.
In version 5.1, the spatial direction indicator string (x, xy, and so on) has been moved
to the end of the variable name. This applies to all vector and tensor variables generated
by the interface.
For example, the diffusive flux vector components have changed (in 5.0 and earlier)from
tcs.dfluxx_w1, tcs.dfluxy_w1, tcs.dfluxz_w1

to (in 5.2 and later)
tcs.dflux_w1x, tcs.dflux_w1y, tcs.dflux_w1z

and the components of the diffusion tensor, defined by the Fick’s Law diffusion model,
have been changed (in 5.0 and earlier) from
tcs.Dfxx_w1, tcs.Dfxy_w1, tcs.Dfxz_w1, tcs.Dfyx_w1, ...

to (in 5.2 and later)
tcs.Df_w1xx, tcs.Df_w1xy, tcs.Df_w1xz, tcs.Df_w1yx, ...

Java ® API Syntax Changes
The API syntax for setting physics properties has been changed in the Transport ofConcentrated Species interface. Now the property name corresponds to the name of
the GUI section containing the property. In order to run Java® files from previous
versions, apply the syntax changes as given in the examples below:
Version 5.0 and earlier:model.physics("tcs").prop("DiffusionModel").setIndex("DiffusionModel","MaxwellStefan", 0);model.physics("tcs").prop("DiffusionModel").setIndex("DiffusionModel","MixtureAveraged", 0);model.physics("tcs").prop("DiffusionModel").setIndex("DiffusionModel","FicksLaw", 0);model.physics("tcs").prop("Convection").setIndex("Convection", "0", 0);74 |CHAPTER 1: RELEASE NOTES

model.physics("tcs").prop("Migration").setIndex("Migration", "0", 0);model.physics("tcs").prop("Regularization").setIndex("Regularization", "1",0);

For version 5.2 and later, change this to:model.physics("tcs").prop("TransportMechanism").set("DiffusionModel","MaxwellStefan");model.physics("tcs").prop("TransportMechanism").set("DiffusionModel","MixtureAveraged");model.physics("tcs").prop("TransportMechanism").set("DiffusionModel","FicksLaw");
model.physics("tcs").prop("TransportMechanism").set("Convection", false);
model.physics("tcs").prop("TransportMechanism").set("Migration", false);
model.physics("tcs").prop("AdvancedSettings").set("Regularization", "0");SURFACE REACTIONS INTERFACE

Updated Internal Variable Names
The same pattern for vector and tensor variable name changes, as described in theTransport of Concentrated Species Interface section above, holds true for the Surface
Reactions interface in version 5.4.

Java ® API Syntax Changes
The API syntax for setting the diffusion tensor of surface species, the molar mass anddensity of the bulk species, and initial values have been changed in the Surface
Reactions interface.

Setting Diffusion Tensor
The surface species name needs to be included in the first argument of the set method.
In order to run Model Java® files from previous versions, apply the syntax changes asshown in the example below:
Version 5.0 and earlier:model.physics("sr").feature("sp1").set("D_0", new String[]{"Dcs1", "0", "0","0", "Dcs1", "0", "0", "0", "Dcs1"});model.physics("sr").feature("sp1").set("D_1", new String[]{"Dcs2", "0", "0","0", "Dcs2", "0", "0", "0", "Dcs2"});For version 5.2 and later, change this to:model.physics("sr").feature("sp1").set("D_cs1", new String[]{"Dcs1", "0","0", "0", "Dcs1", "0", "0", "0", "Dcs1"});model.physics("sr").feature("sp1").set("D_cs2", new String[]{"Dcs2", "0","0", "0", "Dcs2", "0", "0", "0", "Dcs2"});

Setting Molar Mass and Density

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75

The bulk species name needs to be included in the first argument of the setIndex
method. Apply the Java® API syntax changes as shown in the example below:
Version 5.0 and earlier:model.physics("sr").feature("sp1").set("M_0", "Mcb1");
model.physics("sr").feature("sp1").set("M_1", "Mcb2");
model.physics("sr").feature("sp1").set("rho_0", "rhocb1");
model.physics("sr").feature("sp1").set("rho_1", "rhocb2");

For version 5.2 and later, change this to:model.physics("sr").feature("sp1").setIndex("M_cb1", "Mcb1", 0);model.physics("sr").feature("sp1").setIndex("M_cb2", "Mcb2", 0);model.physics("sr").feature("sp1").setIndex("rho_cb1", "rhocb1", 0);model.physics("sr").feature("sp1").setIndex("rho_cb2", "rhocb2", 0);

Setting Initial Values

Apply the Java® API syntax changes as shown in the example below:
Version 5.0 and earlier:model.physics("sr").feature("init1").set("cs1", "cs10");model.physics("sr").feature("init1").set("cs2", "cs20");model.physics("sr").feature("init1").set("cb1", "cb10");model.physics("sr").feature("init1").set("cb2", "cb20");

For version 5.2 and later, change this to:model.physics("sr").feature("init1").setIndex("initcs", "cs10", 0);model.physics("sr").feature("init1").setIndex("initcs", "cs20", 1);
model.physics("sr").feature("init1").setIndex("initcb", "cb10", 0);model.physics("sr").feature("init1").setIndex("initcb", "cb20", 1);76 |CHAPTER 1: RELEASE NOTESComposite Materials Module
New Functionality in Version 5.5
DELAMINATION MODELING

A common failure mode in laminates is delamination. This can be modeled using the
new Delamination node in the Layered Shell interface. There are several different
displacement- and energy-based cohesive zone models available for describing thedamage together with different traction separation laws. When two layers are in adelaminated state, either initially or after applying a load, a contact condition is used
to avoid penetration between the layers.
NEW FAILURE CRITERIA

New failure criteria have been added for layered composites. They are:• Zinoviev• Hashin-Rotem• Hashin• Puck• LaRC03
These criteria are available for the Linear Elastic Material in the Layered Shell interface
and in the Layered Linear Elastic Material in the Shell interface.
MATERIAL ACTIVATION IN LAYERED SHELL INTERFACE

The addition of an Activation node to the Linear Elastic Material in the Layered Shellinterface makes it possible to analyze the stress state in a composite laminate wherecertain layers are added or removed. An example is when you want to model the
addition of material during processes such as additive manufacturing.
NEW MULTIPHYSICS INTERFACE FOR THERMAL STRESS ANALYSIS

A new multiphysics interface for thermal stress analysis, Thermal Stress, Layered Shellhas been added. It couples the Heat Transfer in Shells interface with a Layered Shellinterface. The connection is made using the Layered Thermal Expansion multiphysics
coupling. In the previous version, the name of the corresponding coupling was Thermal
Expansion, Layered Shell.

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77

The Layered Thermal Expansion multiphysics coupling can also connect to a Thin Layerfeature in the Heat Transfer in Solids interface.
The new interface is located in a group named Thermal Stress in the Add Physics dialog.
NEW MULTIPHYSICS COUPLINGS IN LAYERED SHELL INTERFACE

New multiphysics couplings have been enabled for the Layered Shell interface toprovide couplings with fluid load and acoustics. The new multiphysics couplings forthis interface are:• Acoustics-Structure Boundary• Thermoviscous-Structure Boundary• Aeroacoustic-Structure Boundary• Porous-Structure Boundary• Fluid-Structure Interaction
COUPLINGS TO OTHER STRUCTURAL MECHANICS INTERFACES

Two new multiphysics couplings have been added for connecting the Layered Shellinterface to other structural mechanics interfaces.
The Layered Shell-Structure Cladding multiphysics coupling can be used to model cases
where the top or bottom surface of the layered shell is connected to a boundary in the
Solid Mechanics, Shell, or Membrane interfaces.
The Layered Shell-Structure Transition multiphysics coupling makes it possible toconnect edges in a Layered Shell interface either to edges in a Shell interface or toboundaries in a Solid Mechanics interface.
NEW LAYERED LINEAR ELASTIC MATERIAL IN THE MEMBRANE
INTERFACE

A new material model, the Layered Linear Elastic Material, has been added to theMembrane interface to facilitate the modeling of multilayered thin films. It is available
in 3D and 2D axisymmetry.
There are several material models that can be used together with the Layered Linear
Elastic Material; for example, viscoelaticity and plasticity. The nonlinear material models
require the Nonlinear Structural Materials Module.
For structural analysis in the Membrane interface, the ordering of the layers is notimportant, since this is an equivalent single layer theory and the bending stiffness is

78 |CHAPTER 1: RELEASE NOTES

assumed to be zero. The ordering may still be important in a multiphysics context,
though.
LAYERED LINEAR ELASTIC MATERIAL IN 2D AXISYMMETRY

The Layered Linear Elastic Material in the Shell interface is now also available in 2D
axisymmetry.
NONLINEAR MATERIAL MODELS IN THE LAYERED SHELL INTERFACE

Hyperelastic Material has been added as a new top-level material family in the Layered

Shell interface. It contains the same hyperelastic material models (Neo-Hookean,
Mooney-Rivlin, etc.) as in the Solid Mechanics interface. It is also possible to include
viscoelasticity and Mullins effect.
In the Linear Elastic Material in the Layered Shell interface, it is now possible to add
Plasticity. The same set of yield functions and hardening models as in the Solid
Mechanics interface is available. The formulation assumes small plastic strains, whichgive a good approximation up to 10–20% strain.
Nonlinear materials require the Nonlinear Structural Materials Module.
NONLINEAR MATERIAL MODELS IN THE SHELL INTERFACEThe Layered Linear Elastic Material in the Shell interface now has a set of subnodes fordefining new material models. These are:
• Viscoelasticity• Plasticity• Creep• Viscoplasticity
Nonlinear materials require the Nonlinear Structural Materials Module.
PIEZOELECTRIC MATERIAL IN LAYERED SHELL INTERFACE

The addition of a piezoelectric material model to the Layered Shell interface makes it
possible to model thin piezoelectric devices where a piezoelectric material is embedded
in a composite laminate. A new multiphysics interface, Piezoelectricity, Layered Shell,has been added. It combines two physics interfaces, Layered Shell and Electric
Currents in Layered Shells, and a Layered Piezoelectric Effect multiphysics coupling.

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MIXED FORMULATION IN LAYERED SHELL INTERFACEIn the Linear Elastic Material in the Layered Shell interface, a mixed formulation has
been added. Mixed formulations can improve accuracy for materials with low
compressibility.
CONTACT MODELING IN LAYERED SHELL INTERFACE

It is now possible to model contact in the Layered Shell interface. In this release, it ishowever not possible to extend the contact model with friction, adhesion, or
decohesion.
VARIABLE THICKNESS LAYERS IN LAYERED SHELLSIt is now possible to model one or more layers of a composite laminate with a thickness
that is a function of the coordinates. This new functionality is available through the
new Scale setting in the Layered Material Link and Layered Material Stack nodes. In asingle-layer material, a thickness expression can be given directly in the Thickness
property.
Variable thickness layers are supported in the Layered Shell interface as well as in theLayered Linear Elastic Material node in the Shell and Membrane interfaces.
REPETITION OF LAYUP DEFINITIONS

It is now possible to perform various transformation operations on the layup definedin Layered Material in order to avoid defining all layers in structures having symmetries
or being repetitive. The transformations are:• Symmetric• Antisymmetric• Repeated
These transformations are defined by the Transform option in the Layered Material Link
and Layered Material Stack nodes.
SPECIALIZED INTERFACE SELECTIONSIn nodes in the Layered Shell interface that have interface selection, such as Thin Elastic
Layer, a number of special layer selection shortcuts have been added:• Top interface• Bottom interface• Exterior interfaces• All interfaces

80 |CHAPTER 1: RELEASE NOTESDISPLAY OF NORMAL DIRECTIONS IN LAYERED SHELL INTERFACE

When physics symbols are switched on in the Layered Shell interface and a material
model node is selected in the Model Builder, a green arrow will indicate the positive
normal direction (the stacking direction) for each boundary.
THIN ELASTIC LAYER WITH MASSIn the Thin Elastic Layer and Thin Elastic Layer, Interface nodes in the Layered Shellinterface, it is now also possible to assign a mass distribution to the layer. This mass istaken into account both in dynamic analysis and in loads from gravity and rotating
frames.
OUTPUT OF ABD MATRIXThe Layered Linear Elastic Material in the Shell interface now defines a matrix variable
containing the complete ‘ABD’ (elastcity) and ‘abd’ (compliance) matrices. The
variables are named shell.ABD and shell.abd, respectively. They can be used in, forexample, a Point Matrix Evaluation node, and can be found under Shell>Stiffness andflexibility in the Replace Expression dialog.
USE ALL LAYERS OPTION ADDED TO SHELL INTERFACEIn the Layered Linear Elastic Material in the Shell interface, it is now possible to selectseveral layered materials active on different boundaries through the new Use All Layers
check box. In the previous version, this type of selection was only available in theLayered Shell interface.
SYNCHRONIZATION OF ELASTIC PROPERTIES

If isotropic material data (for example, E and ν) are present in a Material, then thismaterial can also be used if the Solid model in a linear elastic material is set to
Orthotropic or Anisotropic. Similarly, orthotropic material data can be used when Solidmodel is set to Anisotropic. This is particularly important in layered structures wheresome layers are anisotropic and other layers are isotropic, since it is now possible to use
a common anisotropic material model in all layers in this situation.
NEW DEFAULT PLOTS

In the Layered Shell and Shell interfaces, new default plots showing the layup angles
are generated. For the former interface, there is also a new default plot showing theshell as a 3D geometry.

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81

RESULT EVALUATION IMPROVEMENTS

New settings have been added to the Layered Material dataset. It is now possible toselect not only boundaries, but also layers and interfaces. It is also possible to define athrough-thickness location when the dataset is referenced in a node under Derived
Values.
In the Layered Material Slice plot, there are several improvements:• In addition to plotting in layers, it is also possible to plot results on interfaces.
• You can define a layout so that an array of plots for several locations are generated
in a single plot node.
• Layer names can be added to the plot automatically, without separate Annotation
nodes.
In the Through Thickness plot, the locations of interfaces between layers can now bedrawn automatically. It is also possible to plot quantities that are only defined in certain
layers.
CONSISTENT NAMING OF STRESS VARIABLES

The same convention is now used for the naming of stress variables in the Layered Shellinterface and the Layered Linear Elastic Material in the Shell and Membrane interfaces.
The following convention is used:• Second Piola-Kirchhoff stress, local coordinate system: Sl• Second Piola-Kirchhoff stress, laminate coordinate system: Slm• Second Piola-Kirchhoff stress, layer coordinate system: Sll

New Models in Version 5.5
PROGRESSIVE DELAMINATION IN A LAMINATED SHELL

Interfacial failure or delamination in a composite material is a common phenomenon.
It can be simulated using a cohesive zone model (CZM). This example shows theimplementation of a CZM with a bilinear traction-separation law in a layered shell. It
is used to predict the mixed-mode softening onset and delamination propagation.
MIXED-MODE DELAMINATION OF A COMPOSITE LAMINATE

This is a benchmark model for delamination, where the results from the Layered Shellinterface are compared with the same model analyzed in the Solid Mechanics interface
and also with published results. A CZM with a bilinear traction-separation is used.

82 |CHAPTER 1: RELEASE NOTESSTRESS AND MODAL ANALYSIS OF A COMPOSITE WHEEL RIM

This example demonstrates the modeling of a wheel rim made of a laminated carbonepoxy composite material. First, a stress analysis of a composite wheel rim is performed,
in which the rim is subjected to an inflation pressure and a tire load. Second, aprestressed eigenfrequency analysis is performed for a range of operating speeds, anda Campbell diagram showing the variation of eigenfrequencies with rotation speed isgenerated.
PIEZOELECTRICITY IN A LAYERED SHELL

This is a tutorial example showing how to model piezoelectric applications using thelayered shell functionality. Two cases of material orientation are studied. In the firstcase, the pole axis is normal to the shell surface, which results in a thickness change. In
the second case, the pole axis is in the plane of the shell, which leads to bending.
CONNECTING LAYERED SHELLS WITH SOLIDS AND SHELLS

Layered shell elements, which are used for modeling composite shells, are often
connected to solid and shell elements in cladding or side-by-side configurations torepresent a realistic structure. For such applications, it becomes important to connect
the layered shell element to other structural elements in an accurate and convenientmanner. In this tutorial and verification problem, you will learn how to connect layered
shell elements to solid and shell elements in different configurations. The results arealso compared to a solid model.

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Corrosion Module
New Functionality in Version 5.5• A new Current Distribution, Pipe interface has been added. The interface is typicallyused to model internal pipeline corrosion.
• The Sacrificial Edge Anode feature now has an option to set zero capacity loss rate
for cathodic current densities in the Secondary Current Distribution interface.
• A new Nernst Equation option is now available for defining the Equilibrium
Potential in Electrode Reactions and Porous Electrode Reaction nodes. In the
Tertiary Current Distribution, Nernst-Planck interface, the concentration
dependence of the equilibrium potential for the Nernst Equation option is defined
automatically based on the reaction stoichiometry.
• The exchange current density for the Butler-Volmer and Linearized Butler-Volmer
kinetics option in Electrode Reaction and Porous Electrode reaction nodes can now
be made automatically concentration dependent. The option is available if the
Nernst Equation option is used when defining the Equilibrium potential. In the
Tertiary Current Distribution, Nernst-Planck interface, the options Mass action law
or Lumped multistep are available for the exchange current density type.
• The Tertiary Current Distribution, Nernst Planck interfaces have changed default
settings to use the Nernst Equation for equilibrium potential, Butler-Volmer for
kinetics expression type, and Mass action law for exchange current density type.
• The Electroanalysis (elan) interface has been replaced with the new Electroanalysis(tcd) entry in the Model Wizard. The new Electroanalysis (tcd) interface provides
seamless switching between the various charge conservation model options
supported by the Tertiary Current Distribution, Nernst-Planck interface.
• The Chemistry interface, added to the Electrochemistry License in version 5.5, now
supports Electrode Reactions and Electrode Reaction Groups. The Chemistryinterface allows for defining multiple species and electrode reactions, as well as
ordinary chemical reactions. Also, mixture and thermodynamic properties, such as
equilibrium potentials, can be calculated automatically by the Chemistry interface.
Variables defined by these features can then be used in any physics interface.
• The Non-Faradaic Reactions nodes now also allow you to set reaction rates for thebulk species in the electrolyte.

84 |CHAPTER 1: RELEASE NOTES• The Common model input has been set as the new default for Temperature model
input in all electrochemistry interfaces.
• The Cyclic Voltammetry boundary condition at the Electrode Surface node andCyclic Voltammetry study step are now available for all Electrochemistry interfaces.
• The Thin Electrode Surface node is now available also in the Primary Current
Distribution interface.
• New and updated default plots have been added in the Transport of Diluted Species,
Tertiary Current Distribution, Nernst Planck, and Darcy’s Law interfaces.
• A new mass inflow boundary condition has been added to Darcy's Law.
• Extended Inlet/Outlet boundary condition in the Darcy’s Law interface to include
Velocity (Inlet/Outlet), Pressure (Inlet/Outlet), and Mass flow (Inlet) options.
• The Darcy’s Law interface now supports frequency-domain studies (with licenses
for the Batteries & Fuel Cells Module, Corrosion Module, Electrochemistry
Module, and Electrodeposition Module).
• More accurate definitions of the internal cH and pH variables (in basic electrolytes),
and the cOH and pOH (in acid electrolytes) in the Tertiary Current Distribution,
Nernst-Planck (water-based charge balance option) and the Electrophoretic
Transport interfaces have been implemented.
• The implementation of the Donnan boundary conditions used by the Ion-Exchange
Membrane node has been improved.
• A new boundary condition formulation option has been added in the Film
Resistance section of the Electrode Surface, Internal Electrode Surface and Thin
Electrode Surface nodes in the Primary Current Distribution interface.
• Default stoichiometric number for Dissolving-Depositing species changed to 0
(from 1).

New and Updated Models in Version 5.5• The new model Internal Pipeline Corrosion Protection Using Resistor Controlled
Cathodic Protection has been added.
• The localized_corrosion_ls and under_deposit_corrosion models have been
updated with new plots for the electrolyte potential.

CORROSION MODULE|

85• The following models have been updated to use the new Electroanalysis (tcd)interface: impedance_spectroscopy, microdisk_voltammetry,
cyclic_voltammetry_1d, and co2_corrosion.
• The impedance_spectroscopy, microdisk_voltammetry, cyclic_voltammetry_1d, andorange_battery models have been updated to use the new Nernst equation andconcentration-dependent exchange current density in Butler-Volmer kinetics.

Backward Compatibility with 5.4• Default stoichiometric number for Dissolving-Depositing species changed to 0
(from 1). Java API backward compatibility may be affected.
• The Tertiary Current Distribution, Nernst Planck interfaces have changed default
settings to use the Nernst equation for equilibrium potential, Butler-Volmer for
kinetics expression type, and Mass action law for exchange current density type. JavaAPI backward compatibility may be affected.

86 |CHAPTER 1: RELEASE NOTESECAD Import Module
New Functionality in Version 5.5• When importing copper layers from IPC-2581 and ODB++ files it is now possible
to automatically exclude symbols located outside the outline of the board.
• The new button Reload Layers is now available in the settings for the Import featurenode for the GDS-II, IPC-2581, and ODB++ formats. Use this button to re-readthe layer information from the ECAD file if the file has changed on disk after thelast time it was imported.
• Support for the ODB++(X) and NETEX-G formats is no longer available.

Backward Compatibility with Version 5.3a
The elevation property of the Import function is now also initialized when setting
the manualelevation property to off. Previously, it was only initialized when setting
the filename property, the manualelevation property is off, and the value of either
the height or importtype properties is changed.

Backward Compatibility with Version 5.2a
• The default value for the sellayer property of the Import function is now on.
Previously, the default was off.
• The default value for the sellayershow property of the Import function is now
all. Previously, the default was dom.

Backward Compatibility with Version 5.0• The default value for the grouping property of the Import function is now layer.
Previously, the default was all.
• For ODB++® and ODB++(X) files (the type property is odb), new rules apply forthe initialization of the importlayer property of the Import function. Now, only
layers of the types Metal and Dielectric are initialized with the string on in theimportlayer string array. Previously, this also included layers of the type Drill.

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Electrochemistry Module
New Functionality in Version 5.5• A new Nernst Equation option is now available for defining the Equilibrium
Potential in Electrode Reactions and Porous Electrode Reaction nodes. In the
Tertiary Current Distribution, Nernst-Planck interface, the concentration
dependence of the equilibrium potential for the Nernst Equation option is defined
automatically based on the reaction stoichiometry.
• The exchange current density for the Butler-Volmer and Linearized Butler-Volmer
kinetics option in Electrode Reaction and Porous Electrode Reaction nodes can
now be made automatically concentration dependent. The option is available if the
Nernst Equation option is used when defining the equilibrium potential. In the
Tertiary Current Distribution, Nernst-Planck interface, the options Mass action law
and Lumped multistep are available for the exchange current density type.
• The Tertiary Current Distribution, Nernst-Planck interfaces have changed default
settings to use the Nernst equation for equilibrium potential, Butler-Volmer for
kinetics expression type, and Mass action law for exchange current density type.
• The Electroanalysis (elan) interface has been replaced with the new Electroanalysis(tcd) entry in the model wizard. The new Electroanalysis (tcd) interface provides
seamless switching between the various charge conservation model options
supported by the Tertiary Current Distribution, Nernst-Planck interface.
• The Chemistry interface, added to the Electrochemistry Module in version 5.5, now
supports Electrode Reactions and Electrode Reaction Groups. The Chemistryinterface allows for defining multiple species and electrode reactions, as well as
ordinary chemical reactions. Also, mixture and thermodynamic properties, such as
equilibrium potentials, can be calculated automatically by the Chemistry interface.
Variables defined by these features can then be used in any physics interface.
• The Non-Faradaic Reactions nodes now also allow you to set reaction rates for thebulk species in the electrolyte.
• The Common model input has been set as the new default for Temperature model
input in all electrochemistry interfaces.
• The Cyclic Voltammetry boundary condition at the Electrode Surface node andCyclic Voltammetry study step are now available for all Electrochemistry interfaces.

88 |CHAPTER 1: RELEASE NOTES• The Thin Electrode Surface node is now available also in the Primary Current
Distribution interface.
• New and updated default plots have been added in the Transport of Diluted Species,
Tertiary Current Distribution, Nernst Planck, and Darcy’s Law interfaces.
• A new mass inflow boundary condition has been added to Darcy’s Law.
• Extended Inlet/Outlet boundary condition in the Darcy’s Law interface to include
Velocity (Inlet/Outlet), Pressure (Inlet/Outlet), and Mass flow (Inlet) options.
• The Darcy’s Law interface now supports frequency domain studies (with licenses for
the Batteries & Fuel Cells Module, Corrosion Module, Electrochemistry Module,
and Electrodeposition Module).
• More accurate definitions of the internal cH and pH variables (in basic electrolytes),
and the cOH and pOH (in acid electrolytes) in the Tertiary Current Distribution,
Nernst-Planck (water based charge balance option) and the Electrophoretic
Transport interfaces have been implemented.
• The implementation of the Donnan boundary conditions used by the Ion-Exchange
Membrane node has been improved.
• A new boundary condition formulation option has been added in the Film
Resistance section of the Electrode Surface, Internal Electrode Surface and Thin
Electrode Surface nodes in the Primary Current Distribution interface.

New and Updated Models in Version 5.5• The following models have been updated to use the new Electroanalysis (tcd)interface: glucose_sensor, impedance_spectroscopy, microdisk_voltammetry, andcyclic_voltammetry_1d.
• The glucose_sensor, impedance_spectroscopy, microdisk_voltammetry,
cyclic_voltammetry_1d, thin_layer_chrono_amperometry, orange_battery, tumor,
and wire_electrode models have been updated to use the new Nernst equation andconcentration-dependent exchange current density in Butler-Volmer kinetics.
• The wire_electrode model has been updated, making use of the Potential Coupling
multiphysics feature.

Backward Compatibility with Version 5.4• The Tertiary Current Distribution, Nernst Planck interfaces have changed default
settings to use the Nernst equation for equilibrium potential, Butler-Volmer for

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kinetics expression type, and Mass action law for exchange current density type. JavaAPI backward compatibility may be affected.

90 |CHAPTER 1: RELEASE NOTESE le c t r o de po s i t i on Mod u l e
New Functionality in Version 5.5• A new Nernst Equation option is now available for defining the Equilibrium
Potential in Electrode Reactions and Porous Electrode Reaction nodes. In the
Tertiary Current Distribution, Nernst-Planck interface, the concentration
dependence of the equilibrium potential for the Nernst Equation option is defined
automatically based on the reaction stoichiometry.
• The exchange current density for the Butler-Volmer and Linearized Butler-Volmer
kinetics option in the Electrode Reaction and Porous Electrode reaction nodes can
now be made automatically concentration dependent. The option is available if the
Nernst Equation option is used when defining the equilibrium potential. In the
Tertiary Current Distribution, Nernst-Planck interface, the options Mass action law
and Lumped multistep are available for the exchange current density type.
• The Tertiary Current Distribution, Nernst-Planck interfaces have changed default
settings to use the Nernst equation for equilibrium potential, Butler-Volmer for
kinetics expression type, and Mass action law for exchange current density type.
• The Electroanalysis (elan) interface has been replaced with the new Electroanalysis(tcd) entry in the Model Wizard. The new Electroanalysis (tcd) interface provides
seamless switching between the various charge conservation model options
supported by the Tertiary Current Distribution, Nernst-Planck interface.
• The Chemistry interface, added to the Electrodeposition Module in version 5.5,
now supports Electrode Reactions and Electrode Reaction Groups. The Chemistryinterface allows for defining multiple species and electrode reactions, as well as
ordinary chemical reactions. Also, mixture and thermodynamic properties, such as
equilibrium potentials, can be calculated automatically by the Chemistry interface.
Variables defined by these features can then be used in any physics interface.
• The Non-Faradaic Reactions nodes now also allow you to set reaction rates for thebulk species in the electrolyte.
• The Common model input has been set as the new default for Temperature model
input in all electrochemistry interfaces.
• The Cyclic Voltammetry boundary condition at the Electrode Surface node andCyclic Voltammetry study step are now available for all Electrochemistry interfaces.

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• The Thin Electrode Surface node is now available also in the Primary Current
Distribution interface.
• New and updated default plots have been added in the Transport of Diluted Species,
Tertiary Current Distribution, Nernst Planck, and Darcy’s Law interfaces.
• A new mass inflow boundary condition has been added to Darcy’s Law.
• Extended Inlet/Outlet boundary condition in the Darcy’s Law interface to include
Velocity (Inlet/Outlet), Pressure (Inlet/Outlet), and Mass flow (Inlet) options.
• The Darcy’s Law interface now supports frequency-domain studies (with licenses
for the Batteries & Fuel Cells Module, Corrosion Module, Electrochemistry
Module, and Electrodeposition Module).
• More accurate definitions of the internal cH and pH variables (in basic electrolytes),
and the cOH and pOH (in acid electrolytes) in the Tertiary Current Distribution,
Nernst-Planck (water-based charge balance option) and the Electrophoretic
Transport interfaces have been implemented.
• The implementation of the Donnan boundary conditions used by the Ion-Exchange
Membrane node has been improved.
• A new boundary condition formulation option has been added in the Film
Resistance section of the Electrode Surface, Internal Electrode Surface, and Thin
Electrode Surface nodes in the Primary Current Distribution interface.
• Default stoichiometric number for Dissolving-Depositing species changed to 0
(from 1).

New and Updated Models in Version 5.5• The new model Electroplating of Multiple Components in a Rack has been added.
• The new model Two-phase flow Modeling of Copper Electrowinning using Bubbly
Flow has been added. (This model also requires the CFD Module to compute.)• The Copper Deposition in a Trench Using the Level Set Method model has been
updated to improve mass conservation.
• The following models have been updated to use the new Electroanalysis (tcd)interface: impedance_spectroscopy, microdisk_voltammetry,
cu_electroless_deposition, and cyclic_voltammetry_1d.
• The impedance_spectroscopy, microdisk_voltammetry, cyclic_voltammetry_1d,orange_battery, cu_trench_deposition_ls, cu_trench_deposition, inductor_coil,microconnector_bump_3d, and fountain_flow models have been updated to use the92 |CHAPTER 1: RELEASE NOTES

new Nernst equation and concentration-dependent exchange current density in
Butler-Volmer kinetics.

Backward Compatibility with Version 5.4• Default stoichiometric number for Dissolving-Depositing species changed to 0
(from 1). Java API backward compatibility may be affected.
• The Tertiary Current Distribution, Nernst Planck interfaces have changed default
settings to use the Nernst equation for equilibrium potential, Butler-Volmer for
kinetics expression type, and Mass action law for exchange current density type. JavaAPI backward compatibility may be affected.

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Fatigue Module
New Functionality in Version 5.5
FATIGUE ANALYSIS IN SOLID ROTOR INTERFACEIn the Fatigue interface, it is now also possible to perform fatigue analysis based on
results from the Solid Rotor interface.
MULTIPLE FATIGUE MODEL NODES IN ONE FATIGUE INTERFACEThe Fatigue interface now supports several fatigue models within the same interface.
This means, for example, that you can evaluate several different fatigue criteria at thesame time using a single Fatigue interface.
THE FATIGUE INTERFACE NO LONGER REQUIRES A DOMAIN SELECTION

The Fatigue interface is now an interface with global scope. In previous versions, it wasa physics interface at the domain level. Thus, there is no longer any geometricalselection at the interface level.
The advantage with the new design is that you do not need to select a domain in orderto do a fatigue evaluation on boundaries, edges, or points. This is particularly
important when evaluating fatigue life in shell models, since such models no longer
require the addition of superfluous domains.

Backward Compatibility with Version 5.3
Several of the fatigue laws for low-cycle fatigue are customarily expressed in terms ofnumber of load reversals.
In previous versions, the distinction between number of load reversals to failure andnumber of load cycles to failure has not been clear, neither in the theory sections nor
in result output. In version 5.3a, the result is always in terms of cycles, and the
documentation has been clarified at a number of places.
The affected fatigue models are Basquin, Coffin-Manson, Combined Basquin and CoffinManson, Morrow, Smith-Watson-Topper (SWT), Wang-Brown, and Fatemi-Socie.

94 |CHAPTER 1: RELEASE NOTESGeomechanics Module
New Functionality in Version 5.5
CHANGES IN THE ELASTOPLASTIC SOIL FAMILY OF MODELS

The relationship between the void ratio and stress has been modified for the Modified
Cam-Clay, Modified Structured Cam-Clay, and Extended Barcelona Basic models. When theoption to specify Poisson’s ratio (ν) is used, then the shear modulus (G) is derived fromν and the current secant bulk modulus. Also, the mean stress is now equal to reference
pressure at zero strain.
For the Modified Structured Cam-Clay model, the angle of internal friction is no longer
available as an input, unless the Slope of critical state line is set to Match to MohrCoulomb criterion.
For the Extended Barcelona Basic model, a new input for initial suction has been added.
The effect is that the volumetric strain is now based on changes in suction, rather thanon the total suction.
For the Hardening Soil model, the expressions for the cap yield functions and plastic
potential have been modified. Also, the expressions for critical deviatoric stress anddilatancy angle have been updated.
NEW TENSION CUT-OFF CRITERION IN SOIL PLASTICITY

For the Mohr-Coulomb and Drucker-Prager models, you can now choose between
two different tension cut-off criteria. Set Tension Cut-off to Mean stress cut-off toemploy the new criterion, which is numerically more stable than the old Principal stress
cut-off criterion.
IMPROVED PERFORMANCE FOR PLASTICITY

The speed of plasticity computations has been improved by up to 20% for several ofthe more common plasticity models.

New Models in Version 5.5
TRIAXIAL TEST WITH HARDENING SOIL MATERIAL MODEL

In this example, a triaxial test is simulated using the Hardening Soil material model.
The test consists of two main stages; an initial isotropic compression, followed by axial

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compressive/tensile loading. A hyperbolic stress-strain relation is recovered. It is also
verified that the asymptotic value of the axial stress is equal to the analytical value ofthe failure stress.
ISOTROPIC COMPRESSION TEST FOR STRUCTURED CLAYSThis model simulates the isotropic compression of naturally structured and artificiallystructured clays using the Modified Structured Cam-Clay (MSCC) material model.
The aim of the example is to reproduce the compression behavior given in abenchmark for four structured clays.
TRIAXIAL AND OEDOMETER TEST WITH MODIFIED CAM-CLAY MATERIAL
MODEL

In this example, triaxial and oedometer tests are simulated using the Modified CamClay material model. A nonlinear stress-strain relation is recovered with the constant
Poisson's ratio formulation. The hardening and softening behavior is recovered fornormally consolidated and highly overconsolidated soils.

96 |CHAPTER 1: RELEASE NOTESHe a t T r a ns f e r Mod u l e
New and Improved Functionality in Version 5.5
NEW LUMPED THERMAL SYSTEM INTERFACEThe Lumped Thermal System interface is now available for heat transfer modeling in
discrete thermal systems. By analogy with electrical circuits, it provides a lumped
element model that idealizes the domain and boundary conditions for heat transfer
into components joined by a network of perfectly thermally conductive wires. It
provides the following global features:• Two-node components: Conductive Thermal Resistor, Thermal Capacitor, Heat Rate
Source, Convective Thermal Resistor, Radiative Thermal Resistor, Thermoelectric
Module, and Heat Pipe.
• One-node components: Temperature, Heat Rate, Radiative Heat Rate, Thermal Mass,and External Terminal.
The new Lumped System Connector feature, available under all Heat Transfer interfaces,
can be used to connect an External Terminal node in the lumped thermal system to a
finite element model in any dimension.
In addition, subsystems may be defined once with the Subsystem Definition component
and then used several times in the circuit with the Subsystem Instance component.
This new set of functionality makes it possible to dramatically reduce the models’complexity by using global features not requiring any geometry nor mesh definition.
The use of the new features is illustrated in the Composite Thermal Barrier, Lumped
Thermal System, Thermoelectric Cooler, Lumped Thermal System, Transient
Conduction in a Wall, Lumped Thermal System, and Buried Cables Heatingtutorials.
EXTENDED CAPABILITIES FOR RADIATION IN PARTICIPATING MEDIAThe Radiation in Participating Media and Radiation in Absorbing-Scattering Media
interfaces have a new Wavelength dependence of radiative properties list under theParticipating Media Settings section. With the Multiple spectral bands option, an
arbitrary number of spectral bands can now be set to model wavelength-dependent
material properties, as for surface-to-surface radiation. The features of the two
mentioned interfaces have been updated to improve usability when multiple spectral
bands are used. It is possible to define material properties such as the absorption

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coefficient, the scattering coefficient or the surface emissivity from a wavelengthdependent function or from a table, with one value per spectral band. The Constantoption of the Wavelength dependence of radiative properties list reproduces the behaviorof the features up to version 5.4.
In addition, the new Radiative Source feature allows you to add a source term in theradiative transfer equation by specifying either a Power density, a Directional power
density, or an Energy rate. It is available in the Radiation in Participating Media andRadiation in Absorbing-Scattering Media interfaces.
Finally, the new Initial Values feature allows you to set a user-defined value for the initialradiative intensity (discrete ordinates method) or incident radiation (P1Approximation). It is available in the Radiation in Participating Media and Radiationin Absorbing-Scattering Media interfaces. In the Radiation in Participating Media
interface, the blackbody formulation can be used for the specification of the initialcondition.
EXTENDED CAPABILITIES FOR SURFACE-TO-SURFACE RADIATION

It is now possible to specify the Ambient emissivity in the features modeling radiative
surfaces (Diffuse Surface and Diffuse Mirror in the Surface-to-Surface Radiationinterface). This is particularly interesting when it is combined with the Multiple spectral
bands option of the Surface-to-Surface Radiation interface to model radiative cooling.
Atmosphere can be modeled as a radiative body that emits at the ambient temperature,and the ambient emissivity can be used to take into account its high emissivity for some
spectral bands, specially for clear-sky conditions.
In addition, the Symmetry and External Radiation Source features are now available
when the Ray shooting radiation method is used. The Symmetry feature can be used todefine up to three symmetry planes or to define sector symmetry in order to reducethe computational effort for the view factor computation. The External Radiation
Source feature can be used to define radiation coming from an object that is not
represented in the model geometry, like the sun. For time-dependent analysis, theexternal radiation source position or direction may vary during the simulation.
Finally, a new option is available to control the view factor update for time-dependent
simulations, when the Ray shooting radiation method is used. The View Factors Update
section is available with the Advanced Physics Options in the Surface-to-Surface
Radiation interface. This allows to define a criterion based on a user-defined
Expression. This may considerably reduce the computation time of time-dependent
simulations.

98 |CHAPTER 1: RELEASE NOTESOPEN BOUNDARY IMPROVEMENTThe Open Boundary feature, available on exterior boundaries of fluid-type domains, has
a new Inflow Condition section to set the inflow from a Danckwerts condition or byusing weak constraints on the temperature. The implementation is unchanged foroutflow. The new Flux (Danckwerts) option applies an inflow of heat coming from avirtual domain with known upstream conditions. This flux is proportional to thetemperature difference between the boundary and the upstream, and it is also
proportional to the flow rate. It tends to prescribe the upstream temperature at theboundary for large flow rate, while the boundary temperature is influenced by thesources and sinks of the adjacent regions for small flow rates. It may improve theperformance of natural convection computations by inducing a smoother numericalformulation.
EXTENDED CAPABILITIES FOR HEAT AND MOISTURE TRANSPORT

A new formulation is available in the Moisture Transport in Air interface to model
convection and diffusion of vapor in air when the vapor content is high. In this case,the moist air density may vary significantly in space and time due to vapor
concentration gradients, and the default Diluted species formulation should be replacedby the Concentrated species one. The new Mixture type for moist air list is available
under the Physical Model section of the physics interface and allows you to choose
between the two abovementioned formulations.
For both formulations, the equations are numerically solved by using the relative
humidity (mt.phi) as the shape function. This information is now displayed under the
Dependent Variables section. Note that the definition of the relative humidity in theHeat Transfer interface (ht.phi) is now consistent with the one of the MoistureTransport interface, with no bounding applied when the relative humidity goes above
unity to allow for supersaturation conditions.
In addition, two new features are available to define flow conditions on the exterior
boundaries of moist air domains:• The Inflow feature allows to specify upstream moisture conditions to define theinflow of moisture that would be obtained if adding a virtual domain upstream of
the inlet. A Dankwerts condition is used to estimate the flux across the boundary.
• The Open Boundary feature behaves identically to the Inflow feature for an incoming
flow, and automatically switches to a zero diffusive flux condition (as with the
Outflow feature) for an outgoing flow. It provides also an alternative way of
specifying the inflow condition by using a Discontinuous Galerkin constraint on thetemperature.

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Moreover, the default solver settings have been updated to improve the numericalconvergence for heat and moisture problems. A Fully Coupled node is set by default,
containing both the temperature and relative humidity variables. Specific parameters(Damping factor, Jacobian update, Maximum number of iterations) are set for stationary
and time-dependent studies. The use of a fully coupled approach strengthens the needof defining consistent initial and boundary conditions, and may require the use of aramp approach to initialize the computation.
The Relative tolerance has been increased in the stationary and time-dependent steps,
and a lower Tolerance factor is used in the Fully Coupled node to compensate. In
particular, this releases the constraint on time steps for time-dependent studies.
Finally, the Moist Air feature is now available within all the Heat Transfer interfaces andcan be found under the new Specific Media menu by right-clicking on the physics
interface node.
EXTENDED CAPABILITIES FOR LAYERED MATERIAL FEATURES

The features and interfaces using the Layered Material functionality for the modeling ofheat transfer in thin structures have been redesigned to improve the user experience inthe model setting process. This process has been especially simplified when a single
layered material is considered, while extended capabilities are available for more
complex applications.
These updates apply to the Thin Layer, Thin Film, and Fracture features (and subfeatures)in the Heat Transfer interface, and to the Heat Transfer in Shells, Heat Transfer inFilms, and Heat Transfer in Fractures interfaces (with all features), found under theHeat Transfer>Thin Structures branch.
It is now possible to select any boundary or edge from the interfaces and features,
while only the geometric entities with a Layered Material defined were available forselection in version 5.4. A Thickness value can be defined in the Material Contents tableof any material.
The Shell Properties section replaces the Layer Selection section in the interfaces and(boundary and edge) features.
By selecting the Nonlayered shell option in the Shell type list, it is possible to set a userdefined Thickness and to apply a classical material on the boundary, like for any otherboundary feature. This simplified approach allows an optimized computation of heattransfer in a single-layer material with a lumped formulation. By default, the Layer typeuses such a lumped formulation, with the Thermally thin approximation option, in the
Solid, Fluid, and Porous Medium features of the Heat Transfer in Shells interfaces.

100 |CHAPTER 1: RELEASE NOTESWith the Layered shell option, you can model temperature variations through the
thickness of the layered material, and it is possible to restrict the computation to a
subset of layers. In addition, you can scale the layer thickness for a single-layer material.
The scale can be defined from arbitrary expressions, in particular, from other physics
quantities. For example, it enables you to define a film thickness from the films
thickness computed by a Thin Film Flow interface.
For the features applying on interfaces between layers, predefined sets of interfaces areavailable in the Interface Selection section to ease the settings.
Finally, the definition of the coordinates system attached to a layered material has been
improved to speed up computation, in particular for models with a very large numberof boundaries.
NONISOTHERMAL FLOW MULTIPHYSICS COUPLING

The Nonisothermal Flow multiphysics coupling has new automatic settings in order toprovide accurate physical results without the need of user action. In particular, thepressure work contribution to the energy equation is automatically added with theCompressible flow option only, and the Include work done by pressure changes check box
has been removed. Changes in results are expected when computing models created inversion 5.4 or earlier, in which the Compressible flow option was used without the
Include work done by pressure changes check box selected.
Also, the Include viscous dissipation check box is now selected by default. This ensuresenergy conservation with the default settings of the multiphysics coupling node. In
addition, it has been updated to give the possibility to couple a single heat transfer
interface to multiple fluid flow interfaces using multiple Nonisothermal Flow
Coupling features.
MISCELLANEOUS• The Heat transfer in alloys and Heat transfer in biological tissue check boxes have been
removed from the Physical Model section of the Heat Transfer interface. The
Biological Tissue and Shape Memory Alloy features, activated by the abovementioned
check boxes, can be found under the new Specific Media context menu when rightclicking on the physics interface node.
• The context menus of the Heat Transfer and Moisture Transport interfaces havebeen reorganized with the addition of the following submenus for domain andboundary features: Specific Media, Flow Conditions, Thin Structures, Heat Sources, andEvaporation/Condensation.

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• The plot menus of the Heat Transfer interface have been reorganized with theaddition of submenus for a better indexing of the predefined variables available forpostprocessing.
• The Ambient Thermal Properties node, available under the Definitions node, has been
moved to the Shared Properties subnode and renamed Ambient Properties. It
contains a new input field for Precipitation rate.
• The mt.delta variable (vapor permeability of still air), required by the Thin Moisture
Barrier feature, has been added to the Moisture Transport in Air interface.
• The definition of the fractional emissive power variable, used, for example, in the
Diffuse Surface feature, has been improved.
• The default solver settings have been improved for models including the Thermal
Expansion multiphysics coupling.
• A warning message has been added when the Heat Transfer with Surface-to-Surface
Radiation coupling node is solved for and one of the linked physics interfaces is not
solved for.
• The values of the normal diffusive heat fluxes at interior boundaries have beencorrected in models with surface-to-surface radiation.

New Applications in Version 5.5
LED BULB COOLING

This example simulates the thermodynamical behavior of a LED bulb and evaluates the
maximal temperature reached inside it while operating. It estimates the temperature of
the system due to the heating of the LED chips, balanced by the cooling by abuoyancy-driven airflow both inside and outside the bulb and radiation to the ambient
surrounding. The geometry of this 3D model includes a realistic representation of the
LED bulb and the surrounding air domain.
COMPOSITE THERMAL BARRIER, LUMPED THERMAL SYSTEM

This new tutorial is a variant of the Composite Thermal Barrier tutorial, in which two
ceramic thin layers with different thermal conductivities are sandwiched in a steel
column. It shows how to connect two 3D finite element domains through a Lumped
Thermal System for the modeling of heat transfer in the ceramic thin layers. The new
lumped approach is validated against the FEM approach.

102 |CHAPTER 1: RELEASE NOTESTHERMOELECTRIC COOLER, LUMPED THERMAL SYSTEM

This new tutorial is a variant of the Thermoelectric Cooler tutorial, in which heattransfer is computed in a thermoelectric cooler. It shows how to use the Lumped
Thermal System interface to estimate the cooling provided by the device over time,and validates the numerical results obtained with the Lumped Thermal Systeminterface against those obtained with the finite element computation made on a 3D
geometry.
TRANSIENT CONDUCTION IN A WALL, LUMPED THERMAL SYSTEM

This new tutorial performs a transient analysis of the temperature through a housewall. The wall is composed of different layers corresponding to the structure,insulation, and plaster. On the exterior and the interior boundaries, the wall is exposedto thermal radiation and convective cooling. The results obtained using the Lumped
Thermal System interface are compared with results obtained with a FEM approachand data from the literature.
BURIED CABLES HEATING

This new tutorial computes the temperature distribution in three buried cables in asituation where the soil surface temperature is known. The temperature profile
obtained with a thermal circuit approach for the cables is compared with a FEM
approach. The thermal circuit properties are established using standard representationof buried cables under the Kennelly assumption (uniform soil surface temperature).
The superposition principle is used to determine the mutual heating of cables in orderto improve the equivalent thermal circuit accuracy.
SURFACE-TO-SURFACE RADIATION WITH DIFFUSE AND SPECULARREFLECTION

This new tutorial shows how to use the Surface-to-Surface Radiation interface tosimulate heat transfer with radiation between diffuse emitters and diffuse-and-specularreflectors. First, it focuses on the validation of the radiative heat flux computation withthe ray shooting algorithm against an analytical solution. Then, the coupling with theHeat Transfer in Solids interface is illustrated.
HOW TO IMPROVE PERFORMANCE OF VIEW FACTOR COMPUTATION FOR
SURFACE-TO-SURFACE RADIATION MODELINGThis tutorial model has been updated to show how to use the features of the Heat
Transfer Module to reduce the computation time and memory usage in view factor
computations. Illustrative results of speedup and memory usage reduction are given
on a benchmark model for the Hemicube and Ray shooting radiation methods.

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HAMSTAD BENCHMARK 1: HEAT AND MOISTURE TRANSPORT IN AN
INSULATED ROOF

This tutorial simulates coupled heat and moisture transport in an insulated roof
structure made of two layers of different properties regarding capillary transport. Thisconfiguration brings a risk of internal condensation at the interface between the twolayers. This 1D model allows to validate the numerical results obtained with COMSOLMultiphysics against the first benchmark defined in HAMSTAD-WP2 (modeling forthe validation of numerical simulations for coupled heat and moisture transport inbuilding materials).
HEAT AND MOISTURE TRANSPORT WITH MOLD GROWTH PREDICTION

This tutorial uses the temperature and relative humidity computed in the precedingtutorial as inputs for a mold prediction model. The VTT model for mold growth anddecline prediction computes a mold index M by solving an ODE, in which the growthand decline rates depend on the time-dependent temperature and relative humidity inthe building material.

Updated Applications in Version 5.5
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, the use of postprocessing features like extrusion datasets,
streamlines with arrows, and temperature discontinuity plots has been extended inorder to produce more explicit results plots.
In addition to these updates, some tutorials have been updated regarding physicalmodeling:• The Condensation Detection in an Electronic Device with Transport and
Diffusion tutorial now uses the Moisture Transport in Air interface for thecomputation of vapor concentration distribution, with the Open Boundary featureapplied at the slits. In addition, the Moist Surface feature has been added on theinterior walls of the device to account for the condensed water accumulated overtime on these surfaces.
• The Evaporative Cooling of Water tutorial uses the new Inflow and Open Boundaryfeatures of the Moisture Transport in Air interface.
• The Free Convection in a Water Glass tutorial now uses an Incompressible flow
formulation with the Boussinesq approximation provided with the Nonisothermal Flow

104 |CHAPTER 1: RELEASE NOTES

coupling node. In addition, the initial temperature has been updated to 278.15 K
to be consistent with the one specified in the model description.
• In the View Factor Computation tutorial, the use of the Symmetry for Surface-toSurface Radiation feature is discussed.
• In the Thermal Analysis of a Turbine Stator Blade tutorial, the temperature range
used for the definition of the material properties has been updated to fit with theoperating temperature range of the model.
In the Heat Conduction in Slab tutorial, the step function definition has been
updated to improve accuracy of the computation.

Backward Compatibility with Version 5.4• In the Inflow feature (Heat Transfer interface), the Upstream absolute pressure user
input is now inactive, unless the new Specify upstream absolute pressure check box
is selected. Scripts using the COMSOL API that used to fill this input field need to
add an instruction for selecting the Specify upstream absolute pressure check box
beforehand.
• The Open Boundary feature now comes with a new default formulation based on the
Danckwerts inflow condition to specify the incoming temperature. The former
default formulation is still available by choosing the Discontinuous Galerkinconstraints option in the Inflow Condition section. To keep the former default
formulation in scripts using the COMSOL API, you need to add the corresponding
instruction to set the Discontinuous Galerkin constraints option in the Inflow Condition
section.
• When the Relative humidity option is used in the Moisture Content boundary
condition, the associated temperature now has to be defined. In version 5.4 andbefore, the moisture transport local temperature was used instead. In order toreproduce previous results, models created in version 5.4 or earlier will use themoisture transport interface temperature when opened in the GUI. The scripts
using the COMSOL API will use the default temperature 293.15 K instead and mayneed to be updated to reproduce existing results.
• In the Heat Flux, Interface and Heat Source, Interface features, when the Heat Rate
option is selected in the Heat Flux and Boundary Heat Source sections, respectively,
the surface definition has been corrected in order to take into account several

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interfaces in the Interface Selection. For example, if two interfaces are selected, thesurface definition is now multiplied by two.
• The Deposited Beam Power, Interface and Surface-to-Ambient Radiation, Interface
features are now applicable on the interior interfaces. In the scripts using the
COMSOL API in which the All interfaces option was selected, the interior interfaces
were selected but no contribution was added on these interfaces. Changes in the
numerical results are expected now that the contribution is added also on theinterior interfaces.

Backward Compatibility with Version 5.3a
• The Heat Transfer in Thin Shells (htsh), Heat Transfer in Thin Films (htsh), andHeat Transfer in Fractures (htsh) interfaces that do not support the Layered Material
functionality are now obsolete. When opening a model created in version 5.3a or
earlier in the GUI, these interfaces are not migrated. They should be manuallyreplaced by the corresponding Heat Transfer in Shells (htlsh), Heat Transfer inFilms (htlsh), and Heat Transfer in Fractures (htlsh) interfaces that support theLayered Material functionality. The Thin Layer, Thin Film, and Fracture features are
replaced by the Solid, Fluid, and Porous Medium features in the new interfaces.
• The Thin Layer, Thin Film, and Fracture features (and their subfeatures) that do notsupport the Layered Material functionality are now obsolete. When opening a model
created in version 5.3a or earlier in the COMSOL Desktop, these features are notmigrated. They should be manually replaced by the corresponding features that
support the Layered Material functionality. Note that the pair features for thin
structures are no longer available for layered materials. The obsolete Thin Layer, Thin
Film, and Fracture features remain available through the COMSOL API so thatexisting scripts remain compatible. However, it is recommended to update thescripts to use the new features as the obsolete features will be discontinued in futureversions.
• The Surface-to-surface radiation check box has been removed from the Physical Modelsection of the Heat Transfer interface. As of Version 5.4, surface-to-surface radiation
models should use the Surface-to-Surface Radiation physics interface coupled witha Heat Transfer domain physics interface via the Heat Transfer with Surface-toSurface Radiation multiphysics coupling feature. The Heat Transfer interface does
not support the Diffuse Surface, Diffuse Mirror, Prescribed Radiosity, Opacity, andExternal Radiation Source features anymore. Models built prior to v5.3a using
surface-to-surface radiation features formerly available in the Heat Transfer
interfaces will mark these features as obsolete. Support for features marked as

106 |CHAPTER 1: RELEASE NOTES

obsolete is not ensured in future versions, thus it is strongly recommended totransfer all these features to a Surface-to-Surface Radiation physics interface and use
a Heat Transfer with Surface-to-Surface Radiation multiphysics coupling feature.
• The Radiation in participating media check box has been removed from the PhysicalModel section of the Heat Transfer interface. From Version 5.4, radiation inparticipating media models should use the Radiation in Participating Media physics
interface coupled with a Heat Transfer physics interface via the Heat Transfer with
Radiation in Participating Media multiphysics coupling feature. The Heat Transfer
interface does not support the Radiation in Participating Media, Opaque Surface,
Incident Intensity, and Continuity on Interior Boundary features anymore. Models
built prior to v5.3a using radiation features formerly available in the Heat Transfer
interfaces will mark these features as obsolete. Support for features marked as
obsolete is not ensured in future versions, thus it is strongly recommended totransfer all these features to a Radiation in Participating Media physics interface anduse a Heat Transfer with Radiation in Participating Media multiphysics coupling
feature.
• The Ambient Settings section has been removed from the Heat Transfer interface.
When opening a model created in version 5.3a or earlier in the COMSOL Desktop,
in which some of the input fields of this section have been edited, an Ambient
Thermal Properties node is automatically created under Definitions>Shared Properties
with the same settings. If some ambient variables have been selected in features, thefeature inputs are updated as well.
• The Phase Change Material feature has been replaced by the Phase Change Material
subfeature. When opening a model created in version 5.3a or earlier in the
COMSOL Desktop, a Fluid node with the Phase Change Material subfeature is
automatically created in place of the obsolete feature. This node is labeled Phase
Change Material in the model.
• The Damaged Tissue section has been removed from the Biological Tissue feature.
When opening a model created in version 5.3a or earlier in the COMSOL Desktop,
in which the Include damage integral analysis check box of this section has been
selected, a Thermal Damage node is automatically added under Biological Tissue withthe same settings. Note that for the Temperature threshold option, it is no longer
possible to perform simultaneous hyperthermia and cryogenic analysis. The
Hyperthermia analysis option is therefore selected by default when opening themodel.
• The Rosseland approximation option, which was available in the Radiation
discretization method list of the Radiation in Participating Media feature, has been

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removed. When opening a model created in version 5.3a or earlier in the COMSOLDesktop, in which this option has been selected, an Optically Thick Participating
Medium subnode is automatically created under the active domain node.
• The Medium Properties feature has been renamed Absorbing Medium in the Radiative
Beam in Absorbing Medium interface, with identical settings and modeling. Whenopening a model created in version 5.3a or earlier in the COMSOL Desktop, an
Absorbing Medium feature is automatically created in place of the obsolete feature.
This node is still labeled Medium Properties in the model.
• The Radiation in Participating Media feature has been renamed Participating Medium
in the Radiative Beam in Absorbing Medium interface. When opening a model
created in version 5.3a or earlier in the COMSOL Desktop, a Participating Mediumfeature is automatically created in place of the obsolete feature. This node is stilllabeled Radiation in Participating Media in the model.
• The Change Thickness and Change Cross Section features have been renamed Thickness
and Cross Section, respectively. When opening a model created in version 5.3a or
earlier in the COMSOL Desktop, these features are not migrated. They should be
manually replaced by the new features.

Backward Compatibility with Version 5.3• The Electromagnetic Heat Source and Boundary Electromagnetic Heat Source coupling
features are now obsolete. They have been merged into a single Electromagnetic
Heating coupling feature. When opening a model created in version 5.3 or earlier in
the COMSOL Desktop, the Electromagnetic Heat Source and Boundary
Electromagnetic Heat Source features are automatically migrated to Electromagnetic
Heating features with selections (respectively a domain and a boundary selection)that match the selections of the migrated features. The obsolete Electromagnetic
Heat Source and Boundary Electromagnetic Heat Source features remain available
through the COMSOL API so that existing scripts remain compatible. However, it
is recommended to update the scripts to use the new Electromagnetic Heating featureas the obsolete feature will be discontinued in future versions. Note thattemperature coupling is enforced in the 5.3a version of the Electromagnetic Heating
coupling feature.
• The Thermoelectric Effect and Boundary Thermoelectric Effect coupling features havebeen merged into a new Thermoelectric Effect coupling feature. When opening amodel created in version 5.3 or earlier in the COMSOL Desktop, the Thermoelectric
Effect and Boundary Thermoelectric Effect features are automatically migrated to the
new Thermoelectric Effect feature with selections (respectively a domain and a

108 |CHAPTER 1: RELEASE NOTESboundary selection) that match the selections of the migrated features. The obsolete
Thermoelectric Effect and Boundary Thermoelectric Effect features remain available
through the COMSOL API so that existing scripts remain compatible. However, it
is recommended to update the scripts to use the new Thermoelectric Effect feature as
the obsolete feature will be discontinued in the future. Note that temperature
coupling is enforced in the 5.3a version of the Thermoelectric Effect coupling feature.
• The Inflow Heat Flux boundary condition is now obsolete. It can be replaced by the
new Inflow boundary condition and the Boundary Heat Source condition.
• The Enable conversions between material and spatial frame check box, displayed in
the Advanced Settings section of the Heat Transfer interfaces when the modelcomponent supports moving mesh, has been removed. This means that conversion
between material and spatial frames is always effective when these frames differ.
• The Energy absorption option has been renamed Arrhenius kinetics in theTransformation model list of the Irreversible Transformation and Biological Tissue
nodes.
• The Convective moisture flux option has been renamed Convective moisture flux,pressures difference in the Moisture Flux node.
• The rhoInt, CpInt, and gammaInt variables, defined by the Fluid domain feature,
have been removed.
• The q_evap variable, defined by the Moist Surface and Wet Surface boundary nodes,
has been replaced by the q_evaptot variable.
The General option for Thin film model has been removed from the Thin Film fallbacknode.

Backward Compatibility with Version 5.2a
The obsolete features Convective Heat Flux and Out-of-plane Convective Heat Flux are
removed in Version 5.3. These were marked as obsolete with a warning message since
Version 5.0. These features will be removed from your model when opening in Version
5.3. Use instead the corresponding Heat flux and Out-of-Plane Heat Flux features, withthe option Convective heat flux. The variables ht.chflux, ht.chflux_u,
ht.chflux_d, and ht.chflux_z defined by these features have been also removed
from equation view and postprocessing variables menu.
The new default option in Thin Moisture Barrier feature is Vapor barrier material
properties, and the Moisture barrier material properties option has been removed. Whenloading a MPH file that was created before version 5.3 this latter option will be cleared,

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and the corresponding user inputs used to define the Moisture transfer coefficient
directly. However, for the API, it will be necessary to update the code with an existing
option name.
In the Equivalent Conductivity for Convection section of the Fluid node, the new
Automatic option for Temperature difference has become the default option. Whenloading a MPH file that was created before version 5.3, the User defined option will be
set automatically with the previous value. However, for the API, it will be necessary to
update the code to set the User Defined option.

Backward Compatibility with Version 5.2
Several enhancements or bug fixes may require an update of the existing applications
or induce a change in the results. Here is the list of the changes:• When Solar position is selected in External Radiation Source, the new option Update
time from solver is selected by default. When loading an MPH file that was created
before version 5.2a this option will be cleared. However, for the API, for timedependent studies, it will be necessary to update the code to get the same behavior
as in previous versions. In most cases, removing the t term in the Second field is thebest option. Alternatively, clearing the Update time from solver option will ensurethat the same behavior as before is obtained.
• The crosswind stabilization of the heat transfer and fluid flow interfaces has been
updated. In general, the update reduces the smoothing induced by the stabilizationcompared to previous version. In addition, when you use the Nonisothermal Flow
multiphysics coupling and the fluid is defined as incompressible, the uncoupled
versions of the streamlines and crosswind stabilization are used.
• Since Pair Thin Film and Pair Fracture are now pair features, their selection needs tobe redefined.
• The definition of the ht.feature.fc(RH.T,pA) function when Moist air fluid type
is used in Fluid feature has been corrected. This change can affect the results insimulations where it is used.
• The frame support has been enhanced to support moving mesh combined with
deformed geometry in the same component.

110 |CHAPTER 1: RELEASE NOTES• The Prescribed Radiosity feature has been updated so that it no longer ignores theTemperature model input.
• In surface-to-surface boundary features, the ambient temperature definition has
been fixed when the Opacity Controlled and Defined ambient temperature on each side
options are used simultaneously.

Backward Compatibility with Version 5.1
CHANGES IN VARIABLE NAMESThe names of the heat capacity variables have changed in several features forconsistency:• In the Bioheat feature, ht.cb has become ht.cp_b.
• In the Thin Layer feature, ht.cs has become ht.cp_s.
• In the Thin Rod feature, ht.cl has become ht.cp_l.
• In the Thin Layered Shell feature, htsh.cs1 has become htsh.cp_s1, and so on.
• In the Heat Transfer in Porous Media feature, ht.c_pp has become ht.cp_p,
ht.c_pp1 has become ht.cp_p1, and so on.
• In the Immobile Fluids feature, ht.c_pg1 has become ht.cp_g1, and so on.
• In the Fracture feature, ht.c_pfr has become ht.cp_fr.
The names of the thermal resistance and absolute thermal resistance variables havechanged in the Isothermal Domain Interface feature:• ht.idi1.Rs has become ht.idi1.R_t• ht.idi1.Rsth has become ht.idi1.R_tth
The name of the fluid viscosity variable has changed in the Local Thermal NonEquilibrium multiphysics coupling: ltne1.mu_f has become ltne1.mu.

Backward Compatibility with Version 5.0
OBSOLETE FEATURES

A number of features are now obsolete because they have been merged or replaced bya more general features. However, when models from COMSOL 5.0 or before containthese features, some of the obsolete features are visible in version 5.2a with a warning
sign notifying that the feature is now obsolete (see Table 1-1). Some features have

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been completely removed (see Table 1-2). A model containing any of them can be
opened in 5.2a, but the feature will be missing.
Updating the models is recommended. Use the new feature and remove the obsoletefeature to make sure that the model will remain compatible with future versions of
COMSOL Multiphysics.
The table below summarizes the changes:
TABLE 1-1: OBSOLETE FEATURES THAT ARE OBSOLETE BUT THAN CAN BE LOADED IN 5.1
OBSOLETE FEATURE

Convective Heat Flux

REPLACE IN 5.2A BY

Heat Flux with the Convective heat flux option

selected
Surface-to-Ambient Radiation

Diffuse Surface with Include surface-to-surface
radiation deselected

Surface-to-Surface Radiation

Diffuse Surface with Include surface-to-surface
radiation selected

Highly Conductive Layer

Thin Layer with Layer type set to Conductive

Thin Thermally Resistive Layer

Thin Layer with Layer type set to Resistive

TABLE 1-2: OBSOLETE FEATURES THAT ARE NO LONGER AVAILABLEOBSOLETE FEATURE

REPLACE IN 5.2A BY

Infinite Element

Infinite Element is no longer defined in thephysics interface. Infinite elements are definedin the Definitions section instead.

Electrochemical Heat flux

Boundary Heat Source

Reaction Heat Flux

Boundary Heat Source

Heat Transfer in Participating
Media

Heat Transfer in Solids contributing to
Radiation in Participating Media

Porous Matrix

Heat Transfer in Porous Media

Note that it is not possible to add any of the obsolete features from the COMSOLDesktop in version 5.2a. Only the new features are available.
OBSOLETE POSTPROCESSING VARIABLES DELETED IN 5.1

List of deleted postprocessing variables: ndflux_acc, ndflux_acc_u, ndflux_acc_d,
ntflux_acc, ntflux_acc_u, ntflux_acc_d, nteflux_acc, nteflux_acc_u,
nteflux_acc_d, qout, qout_u, qout_d, qin, qin_u, qin_d, qw, qw_u, and qw_d.

112 |CHAPTER 1: RELEASE NOTESCHANGES IN VARIABLE NAMES

The variable ht.Tvar, used for nonisothermal flow wall functions, becomes a fully
scoped variable in the following features:• Heat Flux (ht.hf1.Tvar), Line Heat flux, Point Heat flux, and Out of plane heat flux.
• Heat Source (ht.hs1.Tvar), Boundary heat source, Line heat source, and Point heatsource.
• Diffuse Surface (ht.ds1.Tvar).
The fully scoped variables Ptot, Pbtot, Pltot, and Pstot become P0, Pb, Pl, and Ps,
respectively, in the following features:• Heat Flux
• Inflow Heat Flux
• Line Heat Flux
• Heat Source• Boundary Heat Source• Line Heat Source• Line Heat Source (Thin Rod subfeature)• Line Heat Source on Axis
• Layer Heat Source (Thin Layer subfeature)
In the Thermal Contact feature:• Qfric, QfricPow, and Qrate become Qb, Pb, and Qbpart, respectively• Qfric0, Qrate0, Econtact0, hrad0, hgap0, and hconstr0 are removed andmigrated to existing variables Qb, Qbpart, Econtact, hrad, hgap, and hconstr,
respectively, in old models.
The Change Effective Thickness feature from the Heat Transfer in Thin Shells interface
merges htsh.de into the existing variable htsh.ds.
The Heat Transfer in Thin Shells interface also merges the property de and variable
htsh.de into existing property ds and variable htsh.ds. An API command such asmodel.physics("htsh").prop("de").set("de", [...]) now does not have any
effect.

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Obsolete Features
The following features have been removed:• Optically Thick Participating Medium (as a subfeature of Shape Memory Alloy)• Inflow Heat Flux (replaced by Inflow and Boundary Heat Source)• Electromagnetic Heat Source and Electromagnetic Heat Source (replaced byElectromagnetic Heating)• Boundary Thermoelectric Effect (merged with Thermoelectric Effect)• Convective Heat Flux (replaced by Heat Flux with Convective heat flux option)• Out-of-plane Convective Heat Flux (replaced by Out-of-plane Heat Flux with Convective
heat flux option)• Porous Matrix (replaced by Porous Medium)• Infinite Element (replaced by Infinite Element Domain declared in the Definitionsnode)• Electrochemical Heat Flux (replaced by Boundary Heat Source)• Reaction Heat Flux (replaced by Boundary Heat Source)• Heat Transfer in Participating Media (replaced by Heat Transfer with Radiation in
Participating Media)

114 |CHAPTER 1: RELEASE NOTESM E M S M o dule
New Functionality in Version 5.5
RANDOM VIBRATION ANALYSIS

Functionality for random vibration analysis has been added. This type of analysis isintended for situations where the load on a structure is random, but has well-defined
statistical properties that do not change with time. The excitation is described by its
power spectrum density (PSD). If there are several sources of excitation, crosscorrelation spectra are also needed. The output of the analysis is the PSD or RMS of
any linear expression.
In the Add Study dialog, the new study type Random Vibration (PSD) is available. Whenselected, a set of three different studies is added to the model. Also, three nodes are
created under Global Definitions>Reduced-Order Modeling for specifying the spectra.
STUDIES FOR REDUCED-ORDER MODELS

Three new studies for generation and simulation of reduced-order models (ROM)have been added to the Add Study dialog:• Time Dependent, Modal Reduced-Order Model• Frequency Domain, Modal Reduced-Order Model• Time Dependent, AWE Modal Reduced-Order Model
When one of these studies is selected, a set of two or three different studies is added
to the model. Also, two nodes are created under Global Definitions>Reduced-Order
Modeling for providing the input to the ROM.
The old study Modal Reduced-Order Model has been removed from the Add Study dialog.
It has been superseded by the more general Time Dependent, Modal Reduced-Order
Model. It is, however, still possible to add a Modal Reduced-Order Model study step
directly in the solver sequence if you want to access the old functionality.
RESPONSE SPECTRUM ANALYSIS

The response spectrum analysis capabilities that were introduced in version 5.4 are
now also available with a MEMS Module license.

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FLUID-STRUCTURE INTERACTION FOR TWO-PHASE FLOWSIn the Add Physics dialog, two new multiphysics interfaces for two-phase flows havebeen added: Fluid-Solid Interaction, Two-Phase Flow, Phase Field and Fluid-Solid
Interaction, Two-Phase Flow, Phase Field, Fixed Geometry. These interfaces require also alicense that contains the underlying two-phase flow interfaces; that is, the CFD
Module or the Microfluidics Module.
ELASTIC WAVES, TIME EXPLICIT INTERFACEThe new Elastic Waves, Time Explicit interface makes it possible to analyze transient
wave propagation problems in linear elastic materials under small deformations in acomputationally efficient manner. In the Add Physics dialog, this interface is foundunder Elastic Waves in the Acoustics branch.
When the Acoustics Module is available, there is also a new multiphysics interface,
Acoustic-Solid Interaction, Time Explicit, which combines an Elastic Waves, Time Explicit
interface in solid domains with a Pressure Acoustics, Time Explicit interface in adjacent
acoustic domains.
IMPROVEMENTS IN CONTACT MODELINGThe contact modeling functionality has been extended and improved in many aspects.
• Contact can be modeled from a physics interface toward any meshed surface, even
if that surface does not have any physics interface at all defined. This approach isparticularly useful when modeling contact with a rigid shape.
• The more robust penalty method has replaced the augmented Lagrangian method
as the default contact algorithm.
• The friction forces are now represented in a boundary coordinate system. As aneffect, the number of friction degrees of freedom when using the augmented
Lagrangian method is now two in 3D (previous version: three) and one in 2D(previous version: two).
• Adhesion and Decohesion are now two separate subnodes under Contact.
• When using Adhesion, the adhesive layer stiffness can now also be given using elastic
material data by setting Adhesive stiffness to Use material data.
• In Decohesion, there are now new energy-based damage models. Also, you can now
include a viscous regularization in time-dependent analysis in order to mitigate theinherent instable behavior when the material is losing stiffness.

116 |CHAPTER 1: RELEASE NOTES• New default plots showing arrows for contact pressure and friction force are
generated when a Contact node is present.
• The selection of pairs in the Contact node is more intuitive.
In a model created in a previous version, the old type of Contact node will still be kept.
If you add another Contact node, it will be of the new type.
SOLID MECHANICS ON ROTATING DOMAINS

When modeling multiphysics problems in systems where there is a mixture of rotating
and stationary domains, it is now possible to use the Solid Mechanics interface in a
corotating configuration, so that only the deformations relative to the rotation aremodeled. This is far more efficient than solving for the total displacements, including
large global rotations. To this end, the Rotating Frame feature has been extended sothat it can provide a superposition of the rigid body rotation and the relative
displacements for controlling the spatial frame.
NEW DEFAULT SCALE FACTOR FOR EIGENMODES

In the Eigenvalue Solver node within the solver sequence, a new option for scaling
eigenmodes has been added. This option is now used by all structural mechanics
interfaces to ensure that eigenmode amplitudes are small relative to the size of thegeometry. By doing this, it ensures that variables that are nonlinear by their nature will
be evaluated using small perturbations to the original geometry.
MODAL PARTICIPATION FACTORS TABLE

If a Participation Factors node is present under Definitions when an eigenfrequency
study is run, an evaluation group named Participation Factors is automaticallygenerated. It contains a table with the translational and rotational participation factors
for all computed eigenfrequencies.
NEW DEFAULT FOR TEMPERATURE-DEPENDENT PROPERTIES

When material properties have a temperature dependence, the default in the Model
Inputs section is now to take the temperature from Common model input. In versions

prior to 5.5, the default was User defined. In both cases, the default temperature isroom temperature, as long as temperatures are not computed by another physics
interface. With the new formulation, the temperature will automatically be picked up
if defined under Default Model Inputs by a Heat Transfer in Solids interface, forexample. The settings used in a model created in an earlier version are not affected.

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THE TEMPERATURE COUPLING NODE IS OBSOLETE

The Temperature Coupling multiphysics node is no longer used for the transfer oftemperatures from heat transfer interfaces to structural mechanics interfaces. Instead,the common model input mechanism is used for transferring the temperature. Inmodels created prior to version 5.5, the Temperature Coupling node is still present andused. A warning message is however shown.
In all nodes where temperature-dependent properties are referenced, the default value
for the temperature in the Model Inputs section is now Common model input.
SYNCHRONIZATION OF ELASTIC PROPERTIES

If isotropic material data (for example, E and ν) are present in a Material, then thismaterial can also be used if the Solid model in a linear elastic material is set to
Orthotropic or Anisotropic. Similarly, orthotropic material data can be used when Solidmodel is set to Anisotropic.
ENHANCEMENTS FOR CELL PERIODICITYThe Cell Periodicity node in the Solid Mechanics interface has a number of
improvements:• It is now available also in 2D. If the generalized plane strain formulation is used,then it is also possible to generate a global Material node, in the same manner as in
the 3D case.
• One separate global Material node is created for each Cell Periodicity node. This
makes it possible to evaluate several RVE cells in the same study.
• When using Cell Periodicity, a default evaluation group is generated for displaying thecomputed material properties. This group contains a Global Matrix Evaluation node
where the elasticity or compliance matrix is shown.
• The Create button has been replaced by icons in a section toolbar and split into
separate operations for study generation and material node generation.
MAGNETOSTRICTION WITH MAGNETIC HYSTERESISThe Magnetostrictive Material has been extended to include the Jiles–Atherton model
for magnetic hysteresis.
ENHANCEMENTS FOR EXTERNAL MATERIALSWhen implementing your own material using External Stress-Strain Relation or External
Strain, you can now pass back your own warning and log messages, which are displayedin the GUI.

118 |CHAPTER 1: RELEASE NOTESAnother improvement is that the limit for the number of parameters that can be passed
to an external material has been increased significantly.
When using the External Stress-Strain Relation for a plane stress Solid Mechanics
interface in 2D, additional degrees of freedom for the transverse shear strains can be
activated by selecting the Allow transverse shear strains check box. This is needed forsome type of anisotropies in the material model.
NEW SETTINGS FOR ROLLER IN SOLID MECHANICS

The settings in the Roller Constraint section in the Roller node have been changed for2D and 2D axisymmetry in order to reflect the limitations and interpretations that therespective space dimensions impose.
WAVE SPEED COMPUTATION IN ELASTIC MATERIALSFor the Linear Elastic Material and Piezoelectric Material, it is now possible to computewave speeds for elastic waves. To do that, add the Wave Speeds node, available under
Variables in the context menu for the material models or under Attributes on the ribbon
when the material model is selected.
The effect of this node is to make variables for phase and group velocities for elastic
waves available for result presentation. The solution as such is not affected, and thevariables will be available for any study type.
THERMAL STRESS MULTIPHYSICS INTERFACE RENAMED

The Thermal Stress multiphysics interface has been renamed to Thermal Stress, Solid andis now located inside a group named Thermal Stress in the Add Physics dialog. The
reason is that several other similar multiphysics interfaces have been added. Theinterfaces that you actually see in the Thermal Stress group depend on the available
licenses.
COROTATING LOADS ON RIGID DOMAIN

When applying loads in a Rigid Domain node in the Solid Mechanics interface throughthe Applied Force subnode, it is now possible to specify that the load direction follows
the rotation of the body. The new Direction setting has two options: Space-fixed
direction and Body-fixed direction.

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New Models in Version 5.5
PULL-IN AND PULL-OUT ANALYSIS OF A BIASED RESONATOR

An electrostatically actuated MEMS resonator is simulated. The device is driven by an
AC + DC bias voltage applied across a parallel plate capacitor. In this example, the pullin and pull-out voltages of the resonator are computed. This is done via a quasistatic
analysis of the displacement-voltage trajectory of the full range of motion, from theinitial relaxed state all the way to the pulled-in flattened state.
ISOTROPIC-ANISOTROPIC SAMPLE: ELASTIC WAVE PROPAGATIONIn this 2D tutorial model, a test sample consists on one side of an isotropic material
and on the other side of a heterogeneous anisotropic material (a transverse anisotropic
zinc crystal). Elastic waves in the sample are excited by a point-like force. The model
is solved with the Elastic Waves, Time Explicit physics interface.
GROUND MOTION AFTER SEISMIC EVENT: SCATTERING OFF A SMALL
MOUNTAIN

In this tutorial, the propagation of elastic waves is simulated using a 2D model. The
effect of the surface topology on the wave propagation is illustrated when an ideal half
space is modified with the presence of a small mountain. The model is a variation of
Lamb's problem. The propagation of the elastic waves is modeled using the Elastic
Waves, Time Explicit physics interface and the model captures the propagation andscattering of pressure waves, shear waves, Rayleigh waves, and von Schmidt waves.
PIEZOELECTRICITY IN A LAYERED SHELL

This is a tutorial example showing how to model piezoelectric applications using thelayered shell functionality. Two cases of material orientation are studied. In the firstcase, the pole axis is normal to the shell surface, which results in a thickness change. In
the second case, the pole axis is in the plane of the shell, which leads to bending.
SHOCK RESPONSE OF A MOTHERBOARD

Electronic equipment often has to be certified to function after having been subjected
to a specified shock load. In this example, the effect of a 50-g, 11-ms half-sine shockon a circuit board is investigated using response spectrum analysis. The results arecompared with a time-domain analysis using mode superposition.

120 |CHAPTER 1: RELEASE NOTESBackward Compatibility with Version 5.2
The friction slip velocity is no longer defined as a dependent variable. When runninga model using the COMSOL API, you will need to remove the reference to thisvariable in the solver settings. The friction slip velocity is usually defined as<comp>_<solid>_vslip_<pairname>, where <comp> is the tag of the component,<solid> is the tag of the Solid Mechanics physics interface where the Friction node isdefined, and <pairname> is the name of the contact pair.

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Microfluidics Module
New Models in Version 5.5
New models are available showcasing shape and parameter optimization. These models
require the Optimization Module. Specifically:• The Shape Optimization of a Tesla Microvalve model makes use of the new shape
optimization tools to optimize the flow through a microvalve.
• The Parameter Optimization of a Tesla Microvalve model make use of the parameter
optimization to efficiently place obstructions in a microvalve to optimize theforward vs. reverse flow rate.

Backward Compatibility with Version 5.3a
NO FLUX FORMULATION

The formulation of the No Flux feature has been changed in the Transport of Diluted
Species and Transport of Diluted Species in Porous Media interfaces in version 5.4 sothat the flux relative to the convective flux is set to zero. The new formulation is used
when opening a model from a previous session. In the previous formulation, the total
flux was set to zero.

122 |CHAPTER 1: RELEASE NOTESM i xe r M o dule
New Functionality in Version 5.5
ROTATING MACHINERY, TWO-PHASE FLOW, LEVEL SET, AND PHASE
FIELD INTERFACES

The two new physics areas, Rotating Machinery, Level Set and Rotating Machinery,
Phase Field contain physics interfaces for tracking the interface between two
immiscible fluids in geometries with one or more rotating parts. Both laminar andturbulent (RANS) flow is supported. Sliding mesh functionality is applied to enforce
continuity of mass, momentum, and the level set or phase field function between
rotating and stationary domains.
SUPPORT FOR FROZEN ROTOR STUDY STEP AND CONTINUITY PAIRFEATURE IN EULER-EULER MODEL AND BUBBLY FLOW INTERFACES

Rotating machinery simulations of dispersed multiphase flow modeled with the EulerEuler Model and Bubbly Flow interfaces can now be set up manually by adding a
Rotating Domain under Moving Mesh in Definitions and using a Continuity pairfeature (for sliding mesh simulations) between the rotating and stationary domains. In
addition, quasistationary frozen rotor simulations can also be performed due to added
support for this study type.

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Molecular Flow Module
Backward Compatibility with Version 5.0 and Earlier
Due to the fact that multiple species are now supported, some variable names havechanged. In general, variables will now have _G appended to their names, where G is
the name specified for the Incident molecular fluxes in the Dependent Variables section.
So, if a model is updated and resolved, the expressions used in results should bechanged as follows:• The number density should be changed from fmf.N to fmf.N_G.
• The pressure should be changed from p to fmf.p_G.
• The reconstructed number density should be changed from fmf.N to
fmf.ndr1.Nr_G, where ndr1 is the tag of the Number Density Reconstruction
feature.
• Any other variables can be updated using the Replace Expression button available
during results processing.
In addition, new variables exist for the total pressure, number density, and so on:• The total number density, fmf.ntot.
• The total pressure, fmf.ptot.
• The total incident molecular flow, fmf.Gtot.

124 |CHAPTER 1: RELEASE NOTESMultibody Dynamics Module
New Functionality in Version 5.5
CHANGE IN LICENSING STRUCTURE

From version 5.5, the Multibody Dynamics Module is a direct add-on to COMSOLMultiphysics. The module contains two physics interfaces: Multibody Dynamics andLumped Mechanical Systems. In previous versions, the Multibody Dynamics Module
also required the Structural Mechanics Module.
Thus, for basic multibody dynamics modeling, it is no longer necessary to have a
Structural Mechanics Module license. More advanced modeling techniques may still
indirectly require such a license, for example, when combining the Multibody
Dynamics interface with the Shell or Beam interfaces. Also, nonlinear material models
require also the combination of the Structural Mechanics Module (or MEMS Module)
and the Nonlinear Structural Materials Module.
ROLLER CHAIN SPROCKET MODELING

Roller chain sprocket modeling functionality has been added. The new Chain Drive
node in the Multibody Dynamics interface provides a framework for setting up suchmodels. By selecting a chain geometry part in the chain drive node, all the relevant
selections are picked up automatically. Sprockets and chain links can be defined as
being rigid or elastic independently. Using the Create Links and Joints button, all therequired Rigid Domain, Attachment, and Hinge Joint nodes are added automatically.
There are two methods for modeling contact between sprocket and chain links; roller
center based and mesh based. The first one is faster, but works only with rigid links,
whereas the second one is more robust and uses a standard Contact node. It is also
possible to model bushings and losses in the joints.
NEW GEOMETRY PARTS: ROLLER CHAIN SPROCKET

New geometry parts have been added for modeling roller chain sprocket assemblies.
Parts are available for the creation of an individual component as a sprocket or a roller
chain as well as a full roller chain sprocket assembly. In order to make the model setup
fast and easy, the parts are highly parameterized; make use of selection color
functionality; and provide selections such as links, joint boundaries, and contact
boundaries to the physics interface.

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AUTOMATIC RIGID DOMAIN CREATION FROM GEOMETRY OBJECTSThis functionality makes the model setup easier for large rigid multibody systems. A
new section, Automated Model Setup, has been added in the Multibody Dynamics
interface. This section provides buttons to automatically generate physics nodes basedon geometric information. Using the Create Rigid Domains button, rigid domain nodes
are generated for geometrically disconnected objects either on the entire physics
selection or on a subset selection. It is also possible to add Mass and Moment of Inertia
subnodes automatically.
AUTOMATIC GEARS CREATION FROM GEOMETRY PARTS

In the new section Automated Model Setup in the Multibody Dynamics interface, it isalso possible to create gears from geometric information. Using the Create Gears
button, different gear nodes are generated corresponding to each gear part present in
the geometry. All the gear parameters (for instance, number of teeth, pitch diameter,pressure angle, gear center, and gear axis) are automatically entered in the settings forthe auto-generated gear nodes.
IMPROVEMENTS IN CONTACT MODELINGThe contact modeling functionality has been extended and improved in many aspects.
• Contact can be modeled from a physics interface toward any meshed surface, even
if that surface does not have any physics interface at all defined. This approach isparticularly useful when modeling contact with a rigid shape.
• The more robust penalty method has replaced the augmented Lagrangian method
as the default contact algorithm.
• The friction forces are now represented in a boundary coordinate system. As aneffect, the number of friction degrees of freedom when using the augmented
Lagrangian method is now two in 3D (previous version: three) and one in 2D(previous version: two).
• Adhesion and Decohesion are now two separate subnodes under Contact.
• When using Adhesion, the adhesive layer stiffness can now also be given using elastic
material data by setting Adhesive stiffness to Use material data.
• In Decohesion, there are now new energy-based damage models. Also, you can now
include a viscous regularization in time-dependent analysis in order to mitigate theinherent instable behavior when the material is losing stiffness.

126 |CHAPTER 1: RELEASE NOTES• New default plots showing arrows for contact pressure and friction force are
generated when a Contact node is present.
• The selection of pairs in the Contact node is more intuitive.
In a model created in a previous version, the old type of Contact node will still be kept.
If you add another Contact node, it will be of the new type.
NEW DEFAULT SCALE FACTOR FOR EIGENMODES

In the Eigenvalue Solver node within the solver sequence, a new option for scaling
eigenmodes has been added. This option is now used by all structural mechanics
interfaces to ensure that eigenmode amplitudes are small relative to the size of thegeometry. By doing this, it ensures that variables that are nonlinear by their nature will
be evaluated using small perturbations to the original geometry.
MODAL PARTICIPATION FACTORS TABLE

If a Participation Factors node is present under Definitions when an eigenfrequency
study is run, an evaluation group named Participation Factors is automaticallygenerated. It contains a table with the translational and rotational participation factors
for all computed eigenfrequencies.
NEW DEFAULT FOR TEMPERATURE-DEPENDENT PROPERTIES

When material properties have a temperature dependence, the default in the Model
Inputs section is now to take the temperature from Common model input. In versions

prior to 5.5, the default was User defined. In both cases, the default temperature isroom temperature, as long as temperatures are not computed by another physics
interface. With the new formulation, the temperature will automatically be picked up
if defined under Default Model Inputs; for example, by a Heat Transfer in Solids
interface. The settings used in a model created in an earlier version are not affected.
THE TEMPERATURE COUPLING NODE IS OBSOLETE

The Temperature Coupling multiphysics node is no longer used for the transfer oftemperatures from heat transfer interfaces to structural mechanics interfaces. Instead,the common model input mechanism is used for transferring the temperature. Inmodels created prior to version 5.5, the Temperature Coupling node is still present andused. A warning message is however shown.
In all nodes where temperature-dependent properties are referenced, the default value
for the temperature in the Model Inputs section is now Common model input.

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COROTATING LOADS ON RIGID DOMAIN

When applying loads in a Rigid Domain node through the Applied Force subnode, it is
now possible to specify that the load direction follows the rotation of the body. The
new Direction setting has two options: Space-fixed direction and Body-fixed direction.
NEW SETTINGS FOR ROLLER IN 2D

The settings in the Roller Constraint section in the Roller node in 2D have been changed
in order to reflect the limitations and interpretations that the space dimension impose.

New Models in Version 5.5
STRESS ANALYSIS OF A ROLLER CHAIN SPROCKET ASSEMBLY

This example demonstrates a stress analysis of an elastic chain sprocket assembly. The
system consists of a roller chain wrapped around two sprockets in 3D. All thecomponents of the system are assumed to be elastic bodies. An angular velocity isprescribed on the driver sprocket, and load torque is applied on the driven sprocket. A
transient analysis is performed to understand the load path, contact forces, and stress
distribution in various components of the chain drive.
DYNAMICS OF A ROLLER CHAIN SPROCKET ASSEMBLY

This example simulates the dynamics of a chain sprocket assembly. The system consistsof a roller chain wrapped around two sprockets in 2D. The roller chain is constructedby assembling rigid roller plates and pin plates in such a way that the relative rotation
between chain links is unrestricted. This chain is used to transmit rotational motion
between the two sprockets. An angular velocity is prescribed on the driver sprocket anda load torque is applied on the driven sprocket. Using a transient study, the dynamics
of the system are analyzed for two cases: when the driven shaft is loaded and free.
Comparisons of chain link motion, contact forces, and other parameters are made.
SHAFT VIBRATION DUE TO GEAR RATTLE AND BEARING MISALIGNMENT

In a gearbox, vibrations due to rattling of the gears and bearing misalignments are
well-known sources of noise. In this example, two shafts connected through a pair ofgears are considered. The driver rotates at varying speed. Due to backlash in the gears,
the teeth meshing becomes intermittent, thus causing vibration in the shafts. Aftersome time, the driven shaft is loaded with a torque, making the teeth meshing in gears
smooth. In order to analyze the effect of the misalignment on the rotor vibrations, atime-dependent analysis is performed for two cases. In the first case, all bearings arealigned with the shafts, and in the second case, one of the bearings has a small angular

128 |CHAPTER 1: RELEASE NOTES

misalignment. The results show larger torsional and axial vibrations in the shaft in thepresence of misalignment.
ELECTRODYNAMICS OF A POWER SWITCH — MULTIBODY VERSIONElectrical events, such as an overcurrent or overload, can seriously damage electricalcircuits or power lines. To avoid expensive replacements of critical parts, electric switch
circuit breakers can be installed. These mechanically interrupt the current flow or surge
by moving a plunger as soon as a critical current is reached. In contrast to a fuse, which
has to be replaced after it has been activated to protect the surrounding electricalcomponents, a circuit breaker can be reset. The model simulates rigid body dynamics
of the system under the influence of magnetic forces, induced currents, and different
spring/constraint arrangements.

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Nonlinear Structural Materials
ModuleNew Functionality in Version 5.5
NONLINEAR MATERIAL MODELS IN THE SHELL INTERFACE

Three families of nonlinear material models have been added to the Shell interface:• Plasticity• Creep• Viscoplasticity
These material models are added as subnodes to the Layered Linear Elastic Material. If
the Composite Materials Module is available, the material models can also be used in
multilayered shells, and the individual layers can have different material models.
NEW MATERIAL MODELS IN THE LAYERED SHELL INTERFACE

Hyperelastic Material has been added as a new top-level material family in the Layered

Shell interface. It contains the same hyperelastic material models (such as NeoHookean and Mooney-Rivlin) as in the Solid Mechanics interface. It is also possible toinclude viscoelasticity and the Mullins effect.
In the Linear Elastic Material in the Layered Shell interface, it is now possible to add
also Plasticity. The same set of yield functions and hardening models as in the Solid
Mechanics interface are available. The formulation assumes small plastic strains, whichgive a good approximation up to 10–20% strain.
The Layered Shell interface requires the Composite Materials Module.
NONLINEAR MATERIAL MODELS IN THE MEMBRANE INTERFACEIn the Membrane interface, there is a new top-level material model, Layered Linear
Elastic Material. To this node, you can add subnodes for three families of nonlinear
materials:• Plasticity• Creep• Viscoplasticity

130 |CHAPTER 1: RELEASE NOTES

If the Composite Materials Module is available, multilayered thin membranes can bemodeled, and the individual layers can have different material models. This is theprimary use of the Layered Linear Elastic Material and its subnodes.
Since previous versions, the nonlinear material models are available for the standard
Linear Elastic Material in the Membrane interface.
SHAPE MEMORY ALLOY IMPROVEMENTS

In the Lagoudas material model for shape memory alloys, there are several
enhancements:• A stress-dependent maximum transformation strain has been introduced. This
makes it possible to represent the physical observation that, at low stress levels, it is
not possible to reach the maximum transformation strain. This effect is called twoway shape memory effect (TWSME).
• A stress hardening term has been added to represent the variation in the size of thetransformation hysteresis loop with the stress level. The effect is that different slopes
can be observed in phase diagrams.
• A new optional Phase Transformation Direction subnode has been added. In manycases, the direction of the transformation during the process is known. It is thenpossible to improve the convergence significantly by having the transformation
direction prescribed rather than computed. In the previous version, there was asimilar option, but it could only be applied to the structure as a whole, and not toindividual domains.
JOHNSON-COOK MODEL FOR STRAIN-RATE-DEPENDENT PLASTICITY

The Johnson-Cook model is used for describing the effect of high strain rates on theplastic hardening. Effects of temperature softening can also be included. This
hardening model is available as an isotropic hardening model in the Plasticity node andfor the Chaboche and Perzyna models in the Viscoplasticity node.
IMPROVED PERFORMANCE FOR PLASTICITY

The speed of plasticity computations have been improved with up to 20% for severalof the more common plasticity models.

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New Models in Version 5.5
TWISTING AND BENDING OF A METAL FRAME

A thin-walled metal frame with a central cutout is subjected to twisting and bending.
The stresses around the cutout exceed the yield limit, and an elastoplastic analysis isperformed in order to find the residual stresses and strains after unloading. The new
possibility to model plasticity in the Shell interface is used.
PRESSURIZED ORTHOTROPIC CONTAINER — SHELL VERSIONIn this example, plasticity in a thin structure is modeled using the Shell interface. It isa variant of the already existing example Pressurized Orthotropic Container, in which
the same structure is studied using the Solid Mechanics interface.
A thin-walled container made of rolled steel is subjected to an internal overpressure.
As an effect of the manufacturing method, the out-of-plane direction has a higher yieldstress than the other two directions. Hill’s orthotropic plasticity is used to model thedifference in yield strength.
TENSILE TEST WITH STRAIN-RATE-DEPENDENT PLASTICITY

In this example, a tensile test is simulated at four different strain rates. The JohnsonCook hardening law is used to model the strain-rate dependency of the plastic
hardening.
The temperature distribution and thermal expansion caused by the heating generated
by the plastic deformation are also computed. In a separate study, the influence ofincluding a temperature dependency in the Johnson-Cook model is examined.

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Optimization Module
New Functionality in Version 5.5
SHAPE OPTIMIZATION WITH BUILT-IN REGULARIZATION

It is now easier to set up shape optimization problems, because the process of adding
control variables and using them for deforming geometry can be set up automaticallyusing the Free Shape Domain, Free Shape Boundary, and Polynomial Boundary features.
The features are available under Definitions>Shape Optimization. Shells can be
optimized using the Free Shape Shell feature, and all of the features can be combinedwith the Symmetry/Roller to constrain points or edges to slide along boundaries.
TOPOLOGY OPTIMIZATIONThe Filter dataset can be used to transfer the results of a topology optimization to a
new component for a verification analysis. The process is more robust than exportingand importing a STL file, and setting up the new component is easier, because theselections from the old component can be recycled.
The Density Model feature introduced in version 5.4 fixes the material volume factor to
1 outside the selection of the Density Model. In version 5.5, the Prescribed Density
feature can be used to specify a value, θfix, for the material volume factor, and if theDensity Model uses Helmholtz filtering, the filter will be extended using θfix as the input
to the filter.
STRICT ENFORCEMENT OF DESIGN CONSTRAINTS

Design constraints are constraints that can be evaluated without computing thedependent variables. These constraints can be used to prevent topology changes to thegeometry, but unless the constraints are strictly enforced, the topology might change
anyway. Strict enforcement of design constraints prevents evaluation of the geometry
for infeasible design constraints. It is available for COBYLA as well as for coordinate
search and Nelder-Mead, if they use the penalty constraint handling method.
CONFIDENCE INTERVALS FOR LEAST-SQUARES OBJECTIVE

The Levenberg-Marquardt solver can compute the confidence intervals of the control
parameters. The interval is given in the parameter units in the log and in a table.

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PARAMETRIC SWEEP OVER GRADIENT-BASED OPTIMIZATION

A parametric sweep can be added over a gradient-based optimization study step.

New and Updated Models in Version 5.5• The Shape Optimization of a Shell model demonstrates how to perform shape
optimization on shells using the new Free Shape Shell feature. The model uses
geometric nonlinearity.
• The Shape Optimization of a Wrench model increases the stiffness of a wrench
without increasing the mass. The model achieves this using shape optimization with
the Free Shape Domain and Free Shape Boundary features.
• The Shape Optimization of a Tesla Microvalve model has an initial geometry thatis inspired from the Topology Optimization of a Microvalve model. This model
uses the Polynomial Boundary and Symmetry/Roller features to improve thepressure drop ratio (the diodicity), which is a critical performance metric for thistype of device.
• The Shape Optimization of an MBB Beam model imports the optimization result
from the Topology Optimization of an MBB Beam model and uses the Free ShapeBoundary and Symmetry/Roller features to improve on the result.
• The Optimization of an Extruded MBB Beam model illustrates how to perform
topology and shape optimization for problems that have to be modeled in 3D but
where it also has to be possible to extrude the geometry. This model uses theDensity Model feature for the topology optimization and equation-based modelingfor the shape optimization. Extrusion operators are used to ensure the desired
property for the geometry.
• The Optimization Tutorial application is a learning tool that illustrates theproperties of the COMSOL Optimization solvers by making it possible for you totest them on various benchmark problems with two control variables. The
optimization history is plotted in the optimization function landscape, and eachproblem comes with a small explanation.
• The Maximizing the Buckling Load of a Diagonal Brace model demonstrates
how a linear buckling analysis can be combined with the optimization study step toincrease the buckling load of a shell structure while constraining the mass of thestructure.
• The Parameter, Shape, and Topology Optimization of a Beam model is a tutorialmodel that considers a structural mechanics problem and demonstrates how to use
all three types of design optimization available with the Optimization Module.

134 |CHAPTER 1: RELEASE NOTES• The Impedance Tube Parameter Estimation with Data Generation model
illustrates how to model poroacoustics in an impedance tube. Noise is added to a
generated frequency response so that the then noisy response can be used assynthetic data for parameter estimation of the poroacoustic properties.
• The Shape Optimization of an Acoustic Demultiplexer model demonstrates how
to use shape optimization with the Free Shape Boundary feature to achieve
demultiplexing of two acoustic frequency bands. The device has three ports, one
input and two outputs. The objective is that the acoustic energy should go todifferent output ports depending on the frequency. Each frequency band isapproximated with 5 frequencies, giving a total of 10 objective functions, which are
combined in a min-max problem. This problem is solved using the MMA
optimization method. The initially circular cavities are deformed such that the worst
objective is better than 40 dB.

Backward Compatibility with Version 5.4
The computed solution in models using the Nelder-Mead, Coordinate search, orMonte-Carlo method should not change with Enforce design constraints strictly
enabled, compared to the solution obtained in the previous version. The number of
optimization iterations should either decrease or remain unchanged depending on thenumber of infeasible iterations. The computed solution in models using COBYLA candiffer with the Enforce design constraints strictly enabled.

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Particle Tracing Module
New Functionality in Version 5.5
GENERAL SPEEDUP

Some particle tracing models are significantly faster than in version 5.4 and earlier.
There are two main factors in this speedup:• When exerting forces on particles that depend on another field, such as the ElectricForce or the Drag Force, the coupled field is excluded from Jacobian contributions
whenever possible. In this case, the speedup is most significant when the coupledfield has a large number of degrees of freedom, which may occur if the field is solvedfor on a very fine mesh.
• The default behavior of the Time-Dependent Solver for particle tracing is now to
select Minimal from the Jacobian Update list. The previous behavior was Once per time
step. Thus, the Jacobian is updated less often than before. It is not necessary to
update the Jacobian at every time step because the handling of algebraic errors whensolving for the particle trajectories has been made more robust in version 5.5.
VIRTUAL MASS AND PRESSURE GRADIENT FORCES

A built-in option to add the virtual mass (or added mass) and pressure gradient forces
is now available in the Particle Tracing for Fluid Flow interface. In the settings for the
Drag Force, select the check box Include virtual mass and pressure gradient forces.
ACOUSTOPHORETIC FORCE IMPROVEMENTS

New options are available for the Acoustophoretic Force, which has also been renamed
to Acoustophoretic Radiation Force. The new settings include more accurate treatmentof both solid particles and liquid drops, as well as thermodynamic loss models that take
into account the viscous and thermal boundary layers around the particles.

Backward Compatibility
The old options to specify the Particle bulk modulus and Particle compressibility havebeen removed. Now, the speed of sound will always be specified.
NEW OPTION TO SPECIFY PARTICLE DIAMETER

You can now release polydisperse particles by either entering a distribution of particle
masses or a list of particle diameters. Select the appropriate option from the Particle
size distribution list, which replaces the Compute particle mass check box.

136 |CHAPTER 1: RELEASE NOTESPREVIEW INITIAL COORDINATES IN RELEASE FROM GRID

When using the Release from Grid feature to release particles, you can view the initial
particle positions before running the study. Click the Preview Initial Coordinates button
to show the initial positions as points, or click the Preview Initial Extents button to show
a bounding box containing the initial positions.
ISOTROPIC SCATTERING WALL CONDITION

You can now select Isotropic scattering from the Wall condition list in the settings for
the Wall node. This applies random reflection to the particles that hit the wall, like theDiffuse scattering option, but does not follow the cosine law.
RELEASE SECONDARY PARTICLES WITH USER-DEFINED SPEED

When releasing secondary particles during a particle-wall interaction with theSecondary Emission subnode, you now have the option to initialize the particle speed
so that it is equal to the incident particle speed, inversely proportional to the numberof released secondary particles, or user defined. The User defined option is new inversion 5.5.
BUILT-IN SPECIES FOR CHARGED PARTICLE TRACING

In the Particle Properties node for the Charged Particle Tracing interface, you can now
choose from several built-in species, including electrons, protons, neutrons, alphaparticles, and positrons. These choices, along with User defined, are available from theParticle species list.

Important Fixes in Version 5.5
DEFINITION OF THE KNUDSEN NUMBER FOR RAREFACTION MODELSIn the Particle Tracing for Fluid Flow interface, it is possible to apply corrections to
the Drag Force for highly rarefied gases by first selecting the Include rarefaction effects
check box. In version 5.4 and earlier, the rarefaction models Basset, Epstein, and Phillips
used an inconsistent definition of the particle Knudsen number. After a literature
review, it was determined that the original references for these models intended for the
Knudsen number to be defined as the ratio of gas mean free path to particle radius,
whereas some subsequent authors misinterpreted them to define the Knudsen number
as the ratio of mean free path to diameter. Therefore, using these rarefaction models
in version 5.5 will give a different result compared to version 5.4 and earlier.

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MORE ROBUST DIFFUSE SCATTERING ON CURVED INTERIOR SURFACESThe Diffuse scattering wall condition now uses the normal and tangential directions
computed on the boundary mesh element, rather than the directions computed on theunderlying geometric entity, when reinitializing particle velocity. This reduces thelikelihood that particles will fail to locate a subsequent wall interaction when they arereflected in a direction nearly tangent to the interior of a concave surface. In somecases, it may still be necessary to switch to a linear geometry shape order to prevent
some particles from disappearing.
USER-DEFINED RAREFACTION MODEL

An error with the User defined rarefaction correction for the Drag Force in the Particle
Tracing for Fluid Flow interface, in which a text field for the correction factor did notappear, has been fixed.
SPACE CHARGE LIMITED EMISSION WITH AUXILIARY DOFS

In version 5.4, using the Space Charge Limited Emission multiphysics coupling might
give an error message if the coupled Charged Particle Tracing interface included
additional degrees of freedom, such as out-of-plane position or collision counters. Thishas been fixed.
LABELING OF THE AZIMUTHAL AND POLAR ANGLES

In version 5.5, the labeling of azimuthal and polar angles in spherical coordinate
systems has been made more consistent. Now, θ is used for the polar angle and φ isused for the azimuthal angle.
MASS DISTRIBUTION WITH COMPUTE MASS FLOW RATE OPTION

A n error in which the released particle mass could not be initialized in the Particle
Tracing for Fluid Flow interface if the options Specify mass flow rate and Computeparticle mass were used together has been fixed. As a side effect of this bug fix, thenumber of degrees of freedom solved for is expected to slightly increase under thesecircumstances, while the number of static degrees of freedom should decrease.
TANGENTIAL AND NORMAL VELOCITY COMPONENTS IN INLETS

Fixed an error in the Inlet feature for the Particle Tracing for Fluid Flow interface inwhich the initial velocity would be interpreted in global Cartesian coordinates even if
the check box Specify tangential and normal vector components was selected.

138 |CHAPTER 1: RELEASE NOTESVECTOR DISPLAY FOR THE PARTICLE BEAM FEATURE

The Particle Beam feature in the Charged Particle interface more consistently releases
particles in the direction shown by the arrow in the Graphics window. Previously,
particles would sometimes be released in the opposite direction if the Particle Beamselection included interior boundaries.
DEFAULT DATASET GENERATION

The generation of default Particle datasets has been made more robust for cases when
the study contains multiple study steps.
NULL COLLISION METHOD STABILITY IMPROVEMENTThe Null collision method, which can be used with the Collisions feature in theCharged Particle Tracing interface, has been made more robust. It no longer
reinitializes particle coordinates incorrectly when the Store particle status data or Store
particle release statistics check boxes have been selected.
RELEASE STATISTICS WHEN USING THE NOZZLE FEATURE

Fixed an error in the calculation and storage of particle release statistics, like total
number of particles released, when using the Nozzle feature in the Particle Tracing for
Fluid Flow interface.

Backward Compatibility with Version 5.4
REMOVED THE PARTICLE TRAJECTORIES STUDY STEP

The Particle Trajectories study step is obsolete. All instances of this study step have been
replaced with Time Dependent study steps with the same settings.

Backward Compatibility with Version 5.3 and Earlier
NOMENCLATURE CHANGES FOR MULTIPLE PARTICLE SPECIESThe Override Properties feature has been renamed to Particle Properties to emphasizethat it can be used to release multiple species of particles in the same model. The list
Inherit Properties in the settings for most particle release features, such as Inlet andRelease from Grid, has been renamed to Released particle properties.

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TURBULENT DISPERSION CHANGESThe turbulent dispersion models used by the Drag Force in the Particle Tracing for
Fluid Flow interface have been modified and a deprecated turbulent dispersion model
has been removed.
The option Discrete random walk, variable time step has been removed from the
Turbulent dispersion model list. When an old model using this obsolete option is loadedin version 5.3a, the Discrete random walk option is now selected. However, Discreterandom walk actually behaves more like the old Discrete random walk, variable time stepmodel because it only samples the turbulent velocity perturbation at discrete timeintervals based on the eddy lifetime or eddy crossing time in the flow.
CHANGES TO RELEASE FROM EDGE AND POINT

In the Particle Tracing for Fluid Flow interface, the Release from Edge and Release from
Point features now allow the initial particle velocity to be selected from a list containing

previously computed velocity fields, similar to the behavior of the Release and Inletfeatures. This makes the Release from Edge and Release from Point features easier tocouple with another physics interface that models the fluid flow.
CHANGES TO PERIODIC ELECTRIC AND MAGNETIC FORCES

In models built in version 5.3 or earlier, if an Electric Force or Magnetic Force waspresent and the Multiply force by phase angle check box was selected, then in version
5.3a, Time harmonic will be selected from the new Time dependence of field list, which
replaces this check box.

Backward Compatibility with Version 5.2a and Earlier
REFERENCE EDGE FEATURES HAVE BEEN REMOVED

The Reference Edge subnode, which was previously used to specify the orientation of
the transverse beam directions for the Particle Beam feature in 3D, has been removed.
Instead, the orientation of the transverse beam directions is specified using an extra
selection field in the settings window for the Particle Beam feature itself. Similarly, theReference Point subnode for specifying the beam center has been replaced by an extra
selection in the settings window for the Particle Beam feature.

140 |CHAPTER 1: RELEASE NOTESBackward Compatibility with Version 5.2
TURBULENT DISPERSION CHANGESIn the settings window for the Drag Force for the Particle Tracing for Fluid Flowinterface, the Turbulent dispersion check box has been replaced by the Turbulent
dispersion model list. If the check box is selected in a model created in version 5.2 orearlier, then after opening the model in version 5.2a, the option Discrete random walk
will be selected from the list. If the check box is cleared, then None will be selected fromthe list.
PARTICLE DENSITY SPECIFICATIONS MERGED

In version 5.2, when specifying particle properties using the Particle Properties node orOverride Properties node in the Particle Tracing for Fluid Flow interface, it is possible
to specify two different values of the particle density, depending on whether theCompute particle mass check box is selected. In version 5.2a, these two values have been
merged into a single parameter value; that is, the value or expression for the Particle
density will be retained when selecting or clearing the Compute particle mass check box
in the physics interface Advanced Settings section.
PARTICLE BEAM CHANGESThe names of several settings have been changed in the Particle Beam feature for theCharged Particle Tracing interface.
In the Sampling from phase space distribution list, Uniform has been renamed KV.
In the Longitudinal velocity distribution list, Uniform has been renamed None andGaussian has been renamed Normal.
The parameters Position refinement factor and Release distribution accuracy order havebeen removed. Due to some changes in the algorithm for initializing particle positions,in version 5.2a, the distribution of particle positions no longer depends on the finite
element mesh and may differ from the distribution in version 5.2.

Backward Compatibility with Version 5.1
RENAMED PHYSICS INTERFACE SETTINGSThe Release type list in the settings windows for the Charged Particle Tracing andParticle Tracing for Fluid Flow interfaces in earlier versions has been renamed Particle
release specification. For the Charged Particle Tracing interface, the options Static and

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Transient have been renamed to Specify current and Specify release times (the default),

respectively. For the Particle Tracing for Fluid Flow interface, the options Static andTransient have been renamed to Specify mass flow rate and Specify release times (thedefault), respectively.

Backward Compatibility with Version 5.0 and Earlier
OLD NODES FOR PARTICLE-FIELD AND FLUID-PARTICLE INTERACTIONSARE OBSOLETE

The old Particle-Field Interaction and Fluid-Particle Interaction nodes, which could be
added directly to the Charged Particle Tracing and Particle Tracing for Fluid Flowinterfaces, respectively, are now obsolete. They will be removed in a future version.
Simulations of particle-field and fluid-particle interactions should instead use thededicated multiphysics nodes.
ELASTIC COLLISION FORCE NODE HAS BEEN REPLACED

If a model created in version 5.0 or earlier containing the Elastic Collision Force node is
opened in version 5.1 or later, this node will be replaced. If the Collision model in theold Elastic Collision Force node was set to Monte Carlo, a Collisions node with the Elastic
subnode will be created. If instead the Collision model was set to Friction, the Friction
Force subnode will be added.

142 |CHAPTER 1: RELEASE NOTESP i pe Flo w M o d u l e
New Functionality in Version 5.5
PIPE MECHANICS INTERFACEThe new Pipe Mechanics interface is intended for structural analysis of pipes. Theinterface is in many respects similar to the Beam interface in the Structural Mechanics
Module, with important modifications necessary for the analysis of pipes. For instance:• Stresses, strains, and axial deformations caused by internal overpressure are taken
into account.
• The default material model is Fluid and Pipe Materials, reflecting that both thematerial in the pipe wall and the fluid are important.
• The Pipe Cross Section node has more and slightly different input parameters whencompared to the corresponding Cross Section Data node in the Beam interface.
• A special type of load, Fluid Load, is included. There, you enter pressure and dragforces. These values can be taken directly from a Pipe Flow interface.
• A temperature gradient can be present through the pipe wall in the Thermal
Expansion node. The value can be taken directly from a Heat Transfer in Pipes
interface.
The Pipe Mechanics interface requires the Pipe Flow Module or the Structural
Mechanics Module. It is documented in the Structural Mechanics User’s Guide, whichis installed together with the documentation for the Pipe Flow Module.
ACOUSTIC-PIPE ACOUSTIC CONNECTION MULTIPHYSICS COUPLING

The new multiphysics coupling allows to couple the Pressure Acoustics interface to thePipe Acoustics interface. The coupling is between a point and a boundary.
T- AND Y-JUNCTION SELECTIONS IMPROVEMENT

The automatic search for T-junction and Y-junction points is now possible. Thisadditional functionality significantly simplifies the modeling of large pipe networks.

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New Models and Updated Models in Version 5.5
COUPLED ANALYSIS OF FLOW AND STRESS IN A PIPE

A new tutorial model has been added to demonstrate how to use the Pipe Mechanics
interface. The flow in a pipe with a bend is computed using the Pipe Flow interface.
The computed fluid flow load is used as input to a stress analysis in the Pipe Mechanics
interface.
ACOUSTICS OF A PIPE SYSTEM WITH 3D BEND AND JUNCTION

This new tutorial shows how to model the propagation of acoustic waves in large pipe
systems by coupling the Pipe Acoustics interface to the Pressure Acoustics interface.
The tutorial is set up in both the time domain and the frequency domain.
PROBE TUBE MICROPHONE

This model has been updated to use the Acoustic-Pipe Acoustic Connection
multiphysics coupling. This update significantly simplifies setting up the model.

Backward Compatibility with Version 5.3
The old Pipe Connection nodes, which could be added directly to the Pipe Flowinterface and Laminar Flow Interface, respectively, are now obsolete. The samefunctionality is available in a more convenient manner using the Pipe Connection
multiphysics coupling.

Backward Compatibility with Version 5.1 and Earlier
REVISED FORMULATION OF THE PIPE FLOW INTERFACE

The Pipe Flow interface has been amended in version 5.2 with an inertial term. The
stabilization and element shape functions have also been changed. Models created inprevious versions will be opened using the old interface with a notification. For newmodels, only the new interface is available in the physics interface list.

144 |CHAPTER 1: RELEASE NOTES

Plasma Module
New Functionality in Version 5.5
SPACE-DEPENDENT MODELING OF NON-MAXWELLIAN DISCHARGES

It is now possible to compute the EEDF using a two-term approximation of the
Boltzmann equation for 1D and 2D space dependent models.
NEW PHYSICS INTERFACE - CORONA DISCHARGE

A new Corona Discharge physics interface is available. This uses an approximate (nonself-consistent) method to quickly compute the charge distribution in a corona
discharge.
NEW PHYSICS INTERFACE - ELECTRICAL BREAKDOWN DETECTION

A new Electrical Breakdown Detection physics interface uses an approximate method toestimate whether electrical breakdown will occur in an electrical system. The method
integrates Townsend growth coefficients along electric field lines, and determines
breakdown will occur if some threshold quantity is exceeded.

New and Updated Applications and Models in Version 5.5
NEW MODELS• Electrostatic Precipitator• Positive and Negative Corona Discharges• Breakdown Between Spheres• Positive Column with Space Dependent EEDF
• GEC Reference Cell with Space Dependent EEDF

Backward Compatibility with Version 5.3a and Earlier
Due to the way the detailed balance is computed for excitation collisions, models set
up from scratch could provide different results from the same model in version 5.3a.
Models are most likely to be affected if:• The mole fraction of the metastable species is high.
• The electron density is very high (above around 1E20 1/m3).

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The new method for computing the detailed balance is more accurate and physicallycorrect than the method used in version 5.3a and previous.

Backward Compatibility with Version 5.3 and Earlier
There have been several changes that could affect the solution obtained when runninga model in version 5.3a versus 5.3 or earlier. This is due to the following changes andbug fixes:• When electron impact reaction rate constants are computed from cross section data,
due to a bug, the result will be different for the Maxwellian or Druyvesteyn electronenergy distribution functions. For DC discharges, where Townsend coefficients arerecommended, this should not make much of a difference. For inductively coupledor microwave discharges, the average electron density and plasma potential couldchange by as much as 5%, but typically around 2%. If significant differences in thesolution are obtained, it is recommended that you contact support@comsol.com.
• Surface species are no longer available from the context menu. Instead, surface
species will appear in the Model Builder when a surface reaction containing surface
species is added. If the surface reaction is deleted, then the dependent surface species
will also be deleted.
• The rate constant for a surface reaction that uses sticking coefficients has changed,
and is now proportional to the molecular weight of the reactant instead of the mean
molecular weight. In systems where the molecular weight is the same for all species,
this change won’t affect the results. In models containing species with very different
molecular weights, the surface reaction rates may change according to the squareroot of the molecular weight of the reactant divided by the mean molecular weight.
In such systems, it is recommended to activate the new Mixture diffusion correction
property, which adds additional correction terms to the mass flux vector for theheavy species. Overall discharge properties should not be significantly affected bythis change.
• The definition of surface site concentrations and surface reaction rate rates has beencorrected for models that include a surface chemical mechanism where the surface
species have different site occupancy numbers. This should only result in smallchanges to the solution, if any. The total surface site concentration is now a propertyon the physics interface level, rather than computed for each species on the featurelevel.
• The equation to compute binary diffusion coefficients from characteristic lengthparameters has changed. This may produce very slight changes in the diffusion

146 |CHAPTER 1: RELEASE NOTES

coefficients for the heavy species in the Plasma and Heavy Species Transportinterfaces. Any change in the solution due to this should be a tiny fraction of apercent.

Backward Compatibility with Version 5.2 and Earlier
The old Inductively Coupled Plasma and Microwave Plasma interfaces can still be
opened, edited, and solved. When such a model is opened, a warning is given
indicating that the interface is obsolete and will eventually be removed.

Backward Compatibility with Version 5.1
Models using the Reduced Electric Fields study will interpret the unit in the edit field
for the Reduced electric fields as Townsend. For example, when opening a model
created in version 5.1, if the value for the Reduced electric fields was 10, this will now
appear as 10[Td] in the study settings.

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Ray Optics Module
New Functionality in Version 5.5
NEW RAY RELEASE FEATURES FOR MULTISCALE MODELING

Two new ray release features, Release from Electric Field and Release from Far-Field
Radiation Pattern, are now available. These features can be used for multiscale
electromagnetics modeling.
To use these features, first solve for the electric field in the immediate vicinity of aradiation source using the Electromagnetics, Frequency Domain interface or theElectromagnetic Waves, Beam Envelopes interface. Typically, the modeling domain is
only a few wavelengths or less in each direction. Then, use the electric field to initialize
the intensity and polarization of the released rays, which can then propagate for many
wavelengths without the need for a very fine mesh.
The Release from Far-Field Radiation Pattern feature sends rays in multiple directions
with an intensity profile that matches the radiation pattern computed by the Far-Field
Domain feature, allowing it to conveniently use antennas or waveguides as radiation
sources in Ray Optics models.
SPOT DIAGRAM PLOT

The new Spot Diagram plot can be used to display the intersection points of rays witha surface, either a real physical boundary in the model or an intersecting plane. Often,
the intersection points with the focal plane are used to report on the performance ofan optical system.
The Spot Diagram has built-in options to filter or sort the rays shown to automaticallylocate a plane of minimal rms spot size and to insert text annotations into the plot.
The Optical Aberration plot has also been extended to include many of the same
filtering, sorting, and automatic focusing capabilities of the Spot Diagram plot.
GRATING IMPROVEMENTS

The existing Grating feature has been improved, and a new Cross Grating feature is now
available. Use the Grating for a substructure that is periodic in one direction andhomogeneous in the orthogonal direction. Use the Cross Grating when thesubstructure is periodic in two different directions.

148 |CHAPTER 1: RELEASE NOTESFor the Grating, you can now specify either relative or absolute diffraction orders.
Relative orders allow you to easily release the order closest to the direction controlled
by a user-specified Blaze angle.
BETTER MULTITHREADING SUPPORTThe algorithm to model ray-boundary interactions has better multithreading support
than in previous versions. For a sufficiently large number of rays, the computation time
may be reduced on computers with multiple cores, especially if the rays are reflectedmany times and the media are homogeneous.
AIR MODEL IN THE VOID DOMAIN

There is now a built-in setting to treat the void region outside the selected geometry
domains as air, where the refractive index is accurately computed as a function ofpressure and temperature. The difference in refractive index between air and vacuum
plays an important role in the design of optical systems.
PREVIEW INITIAL COORDINATES IN RELEASE FROM GRID

When using the Release from Grid feature to release rays, you can view the ray release
positions before running the study. Click the Preview Initial Coordinates button to show
the initial positions as points, or click the Preview Initial Extents button to show abounding box containing the initial positions.
ISOTROPIC SCATTERING WALL CONDITION

You can now select Isotropic scattering from the Wall condition list in the settings for
the Wall node. This applies random reflection to the rays that hit the wall, like theDiffuse scattering option, but does not follow the cosine law.
NEW RELEASE TYPE: HEXAPOLAR CONE

You can now release rays from a point so that their initial ray directions follow ahexapolar distribution.
NEW PARTSThe Part Libraries for the Ray Optics Module have been considerably extended inversion 5.5.

AspheresNew aspheric lens and mirror parts are now available:• Aspheric even lens (or mirror)• Aspheric odd lens (or mirror)

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• Aspheric lens (or mirror) where the surface sag is defined using a Q-type polynomial
basis to describe the deviation from a best fit sphere• Aspheric lens (or mirror) where the surface sag is defined using a Q-type polynomial
basis to describe the deviation from a best fit conic
The advantage of the Q-type polynomials is that all of their coefficients are of a similarorder of magnitude, whereas in the even and odd aspheres, the coefficients can change
by many orders of magnitude. Thus, the Q-type aspheres are arguably less susceptible
to roundoff error when very-high-order terms are included.

Doublet and Triplet Lenses
Built-in spherical doublet and triplet lenses are included. The inner surfaces can either
be air-spaced or in contact.

Polygonal Mirrors
The new polygonal mirror parts include the following:• Conic polygonal mirror off axis
• Conic polygonal mirror on axis
• Spherical polygonal mirror
Polygonal mirrors are frequently used in larger telescopes where a single larger mirror
is difficult or expensive to manufacture.

New Applications in Version 5.5
COMPACT CAMERA MODULE

Compact camera modules are widely used in electronic devices such as mobile phones
and tablet computers. In order to reduce both the size and number of elements
required, the optical design will typically incorporate several highly aspheric surfaces.
This model demonstrates a five-element design using the Aspheric Even Lens 3D partfrom the Ray Optics Module Part Library.
GREGORY–MAKSUTOV TELESCOPE

The Gregory–Maksutov telescope is a simple catadioptric telescope comprising a
spherical corrector lens and a spherical primary mirror. In this example, the corrector
lens and mirror are formed using the Spherical Lens 3D and Spherical Mirror 3D parts,
respectively, from the Ray Optics Part Library.

150 |CHAPTER 1: RELEASE NOTESKECK TELESCOPEThe Keck Telescope is a 10-meter diameter telescope with a Ritchey–Chretien opticaldesign. It is noted for being one of the first large optical telescopes to utilize alightweight segmented primary mirror. This tutorial demonstrates how to use built-in
polygonal mirrors from the COMSOL Part Library to construct a model of the Keck
Telescope segmented primary mirror.
SCHMIDT-CASSEGRAIN TELESCOPEThe Schmidt–Cassegrain telescope demonstrated in this tutorial is a classic designusing an aspheric corrector lens and two spherical mirrors. The aspheric corrector iscreated using the Aspheric Even Lens 3D part from the Ray Optics Part Library.
CROSS GRATING ÉCHELLE SPECTROGRAPH

This tutorial demonstrates the use of a Cross Grating feature in an échelle
spectrograph. A cross grating is a periodic surface with two directions of periodicity. In
this model, the cross grating is used in high order in one direction and in first order inthe orthogonal (“cross”) direction. By this means, a two-dimensional cross-dispersed
spectrum can be produced with a single grating. A parametric sweep across several
orders is made and the resulting ray and spot diagrams are generated.
NEWTONIAN TELESCOPE STRUCTURAL ANALYSISThis tutorial demonstrates a structural analysis of a simple telescope. The deformationof the telescope structure under gravity is examined and the effect on image quality isdemonstrated.
PETZVAL LENS STOP ANALYSIS WITH HYPERELASTICITYThis model demonstrates an integrated structural-thermal-optical performance(STOP) analysis of an optical system using a nonlinear material model. The Petzval
Lens STOP analysis tutorial is used as the basis for this model. The lens supports aremodeled using a hyperelastic material feature. The resulting displacement and stressfields within the optical system are shown together with nominal and best focus spot
diagrams.
RAY RELEASE BASED ON A PLANE ELECTROMAGNETIC WAVEThis tutorial shows how to set up a ray release based on the incident electric field at aboundary. First, the Electromagnetic Waves, Frequency Domain interface is used tosolve for the electric field of a plane wave. Then, rays are released with initial intensityand polarization matching that of the electric field at the releasing boundary.

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RAY OPTICS WITH A DIPOLE ANTENNA SOURCE (3D)

In this tutorial model, the far-field radiation pattern of a dipole antenna is computed
in a 3D model component. Then, in a separate 3D model component, a ray is releasedusing the far-field radiation pattern to initialize the ray's intensity, polarization, andphase.
RAY OPTICS WITH A DIPOLE ANTENNA SOURCE (2D AXISYMMETRIC)

In this tutorial model, the far-field radiation pattern of a dipole antenna is computed
in a 2D axisymmetric model component. Then, in a separate 3D model component, a
ray is released using the far-field radiation pattern to initialize the ray's intensity,
polarization, and phase.

Important Fixes in Version 5.5
MORE ROBUST DIFFUSE SCATTERING ON CURVED INTERIOR SURFACESThe Diffuse scattering wall condition now uses the normal and tangential directions
computed on the boundary mesh element, rather than the directions computed on theunderlying geometric entity, when reinitializing the ray direction. This reduces thelikelihood that rays will fail to locate a subsequent wall interaction when they arereflected in a direction nearly tangent to the interior of a concave surface, like the insideof a tube. In some cases, it may still be necessary to switch to a linear geometry shapeorder to prevent some rays from disappearing.
LABELING OF THE AZIMUTHAL AND POLAR ANGLES

In version 5.5, the labeling of azimuthal and polar angles in spherical coordinate
systems has been made more consistent. Now, θ is used for the polar angle and φ isused for the azimuthal angle.
DEFAULT DATASET GENERATION

The generation of default Ray datasets has been made more robust for cases when the
study contains multiple study steps.
LINEAR POLARIZER WITH RAY POWER COMPUTATIONThe Linear Polarizer boundary condition no longer gives an error when ray power issolved for in the Geometrical Optics interface.

152 |CHAPTER 1: RELEASE NOTESMIRROR WITH RAY INTENSITY AND POWER

An error message that appeared when adding Accumulator subnodes to the Mirror
boundary condition in the Geometrical Optics interface, while also solving for ray
intensity and power, has been fixed.

Backward Compatibility with Version 5.4
HANDLING OF GRATING ORIENTATION DIRECTION

The handling of grating orientation has been made more robust and consistent inversion 5.5 compared to previous versions. Occasionally, this means that the directions
associated with positive and negative diffraction orders will appear reversed when
opening an older model in version 5.5.
To assist in the reassignment of any grating orientation directions, the direction
associated with positive diffraction orders will be indicated by an arrow in the Graphics
window.
RENAMED RAY RELEASE FEATURESThe Inlet feature has been renamed to Release from Boundary.
The Inlet on Axis feature has been renamed to Release from Symmetry Axis.
RENAMED RAY STATISTICS

Some variables for the ray statistics have been renamed. Here, <phys> is the physics
identifier and <feat> is the tag of a ray release feature.
• <phys>.rmaxall has been renamed to <phys>.rmax.
• <phys>.rmidrms has been renamed to <phys>.rmrms.
• <phys>.<feat>.rmaxrel has been renamed to <phys>.<feat>.rmax.
• <phys>.<feat>.rmidrms has been renamed to <phys>.<feat>.rmrms.

Backward Compatibility with Version 5.3 and Earlier
DIFFRACTION GRATING SETTINGS MOVED TO A SUBNODE

In version 5.3 and earlier, the Grating feature for the Geometrical Optics interface
automatically released transmitted and reflected rays of diffraction order zero. In
version 5.3a, the rays of diffraction order zero are controlled by a Diffraction Ordersubnode, as are all other diffraction orders that might be released.

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NEW OPTIONS FOR SPECIFYING DIFFRACTION GRATING ORIENTATIONIn the Grating feature for the Geometrical Optics interface, the options to control
grating orientation in 3D have been reorganized and expanded. It is now possible tospecify either the direction of the grating lines or the direction of periodicity in thegrating surface. The input Grating orientation specification has been renamed Directionof grating lines.
NEW OPTIONS FOR SPECIFYING REFLECTANCE OR TRANSMITTANCE

In the Geometrical Optics interface, the settings to control Thin dielectric films on
boundary in the settings for the Material Discontinuity feature have been renamed andrearranged.
The old options Single layer, specified reflectance and Single layer, specified
transmittance have been renamed to Specify reflectance and Specify transmittance,

respectively. For both of these options and for the Anti-reflective coating option, which
has not been renamed, the Treat as single layer dielectric film check box is selected when
opening the model in version 5.3a. Otherwise, this check box is cleared, which is thedefault behavior.
ADJUSTMENT TO THE RAY TERMINATION FEATURE

In the Ray Termination feature for the Geometrical Optics interface, the Termination
criteria list has been renamed Additional termination criteria.
REMOVED CHECK BOXES FOR OBSOLETE FUNCTIONALITY

In the settings for the Geometrical Optics interface, the Allow propagation outside
selected domains check box has been removed. This check box was flagged as obsolete

in version 5.3, so clearing it would have created a Warning node.
In the Settings window for the Release from Grid feature, the check box Suppress
interaction with coinciding exterior boundaries has also been removed.

Backward Compatibility with Version 5.2a and Earlier
REFERENCE EDGE FEATURES HAVE BEEN REMOVED

The Reference Edge subnode, which was previously used to specify the orientation ofsome optical components in 3D, has been removed. Instead, the orientation of thesecomponents is specified directly in the parent feature settings using an extra selection
input. The following features are affected:• Linear Polarizer

154 |CHAPTER 1: RELEASE NOTES• Linear Wave Retarder• Mueller Matrix• Grating

Backward Compatibility with Version 5.2
ANISOTROPIC REFRACTIVE INDICES CAN NO LONGER BE SPECIFIED

In version 5.2 and earlier, it is possible to specify an anisotropic refractive index in thesettings window for the Medium Properties node, despite the fact that the anisotropy of
the refractive index is not taken into account when modeling ray propagation. In
version 5.2a, only isotropic refractive indices can be specified in the settings window
for the Medium Properties node. If an anisotropic refractive index was specified in anolder version, then when opening the model in version 5.2a, all of the diagonal terms
will be populated using the first diagonal value and all off-diagonal terms will be set tozero.
RENAMED INTENSITY COMPUTATION METHODSThe options in the Intensity Computation list in the settings window for theGeometrical Optics interface have been renamed.
• Using principal curvatures has been renamed to Compute intensity.
• Using principal curvatures and ray power has been renamed to Compute intensity andpower.
• Using curvature tensor has been renamed to Compute intensity in graded media.
• Using curvature tensor and ray power has been renamed to Compute intensity andpower in graded media.
RENAMED POLARIZATION SETTING

In the Initial polarization type list, available for most ray release features in theGeometrical Optics interface, the option Partially coherent has been renamed toPartially polarized.
CHANGES TO PERTURBATIONS FOR SOLAR RADIATION

The treatment of perturbations due to sunshape and surface roughness has beenchanged in version 5.2a. This change affects the Illuminated Surface and Solar Radiation
features for the Geometrical Optics interface.

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The Use corrections for finite source diameter check box has been replaced by theCorrections for finite source diameter list. If the check box was selected, Create light
cones at release points will be selected from the list after opening the model in version
5.2a. If the check box was cleared, None will be selected from the list.
For the Illuminated Surface, the Standard deviation of the angle of incidence parameterhas been renamed Surface slope error and is now used to define a Rayleigh distribution
for perturbations to the surface normal, rather than the angle of incidence of radiation.
To account for the different effect that the surface slope error has on the model, any
value or expression entered for the Standard deviation of the angle of incidence in version
5.2 or earlier will be divided by 2, before being used to specify the Surface slope error
in version 5.2a.
The Number of rays in wave vector space Nw,r has been removed. The effect of surface
roughness can no longer multiply the number of degrees of freedom created by arelease feature at each release point.
ACTIVATION CONDITIONS ON OPTICAL COMPONENTS

The following boundary conditions require some form of ray intensity computation inorder to have any effect on the solution:• Linear Polarizer• Linear Wave Retarder• Circular Wave Retarder• Ideal Depolarizer• Mueller Matrix
If any of these features is present in a model created in version 5.2 or earlier, and Noneis selected from the Intensity computation list in the settings window for theGeometrical Optics interface, then the feature will be automatically disabled when themodel is opened in version 5.2a. To enable these features, select any option other thanNone from the Intensity Computation list.

Backward Compatibility with Version 5.0
RENAMED SETTINGS

The Wall condition Bounce has been renamed to Specular reflection.

156 |CHAPTER 1: RELEASE NOTESCHANGES TO FREQUENCY-DEPENDENT MATERIAL PROPERTIESThe Frequency-dependent refractive indices check box has been renamed to Allow
frequency distributions at release features.
Expressions involving the ray frequency must always be included within the noenv()
operator. Some expressions for user-defined refractive indices may fail to be evaluatedproperly in version 5.2a unless this operator is applied.
THIN DIELECTRIC FILM SETTINGS

In version 5.0, if the ray intensity is computed, the option to add Thin Dielectric Filmnodes to a Material Discontinuity node is always available. In version 5.2a, the Thin
Dielectric Film subnode can only be added if Add layers to surface or Add layers tosurface, repeating is selected from the Thin dielectric films on boundary list in the Material
Discontinuity settings window. If a model created in version 5.0 is opened in version
5.2a, and any Thin Dielectric Film nodes have been added, then Add layers to surface isselected from the Thin dielectric films on boundary list instead of the default None.
CHANGES TO THE CIRCULAR WAVE RETARDERThe Retardance of the Circular Wave Retarder now indicates the rotation angle of thepolarization ellipse of a ray that passes through the device. In version 5.0, theretardance corresponds to half of this rotation angle. The behavior of the Circular Wave
Retarder is now consistent with the documentation. If a model created in version 5.0
is opened in version 5.2a, the expression for the Retardance of any Circular Wave
Retarder node is multiplied by 2.
OBSOLETE DEPOSITED RAY POWER NODEThe Deposited Ray Power node for absorbing domains is obsolete and will be removed
in future versions. For simulations in which rays generate heat due to absorption, theRay Heat Source multiphysics node should be used instead.

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RF Module
New Functionality in Version 5.5
ADDITIONAL RF MATERIAL LIBRARY FOR DIELECTRIC

The RF material library includes more than 25 dielectric materials from the company
Premix Group to assist in modeling millimeter-wave applications.
MIXED-MODE S-PARAMETERS

The mixed-mode S-parameters are calculated using a full S-parameter matrix of a fourport network that is composed of four single-ended lines. This describes the responses
of a circuit with balanced ports excited and terminated by two types of modes:
common and differential modes.
SPECIFIC ABSORPTION RATE (SAR)

A predefined postprocessing variable is available for the calculation of specificabsorption rate (SAR); that is, the amount of exposure from radio frequency (RF)emission without going through manual definition of multiple variables.
TRANSVERSE ELECTROMAGNETIC (TEM) TYPE PORTA new port type, transverse electromagnetic (TEM), in the Port boundary condition
has been added to address the mode field of a port configured by user-defined electric
potential and ground settings.
VIA TYPE LUMPED PORTA new lumped port type, called Via, is useful to terminate or excite metallic boundaries
of cylindrical shape, such as via holes.
PORT UTILITY

Cutoff Frequency Calculator
A cutoff frequency calculator is available from the rectangular and circular port type
Settings windows. This helps to quickly identify the cutoff frequency for a given modein an arbitrary-sized waveguide.

158 |CHAPTER 1: RELEASE NOTESCoaxial Line Impedance Calculator
A coaxial line impedance calculator is available for the Lumped Port boundary
condition. The impedance of an arbitrary coaxial geometry can be computed without
going through a simulation.
ADDITIONAL 3D FAR-FIELD FUNCTIONS FROM 2D AXISYMMETRICCOMPONENT MODEL

Effective 3D antenna gain and realized gain functions for 2D axisymmetric models areadded.
DEFAULT PROBE PLOT

The default S-parameter plot generated when running a frequency or parametric sweep
is visualized and dynamically updated during the simulation.
COUPLING FROM FULL-WAVE TO RAY OPTICS SIMULATION

Two new features, Release from Electric Field and Release from Far-Field Radiation
Pattern, have been added to the Geometrical Optics interface in the Ray Optics
Module that either release rays based on a near field or far field computed from a fullwave simulation. The full-wave field can be produced by the Electromagnetic Waves,Frequency Domain interface in the RF Module.
GAUSSIAN BEAM INPUT OPTION FOR SCATTERING BOUNDARYCONDITION

The Scattering boundary condition has a new option for the Incident field list.
Choosing the Gaussian beam option allows you to propagate a Gaussian beam into anarbitrary direction. The Gaussian beam is defined using the paraxial Gaussian beamformula.
POLARIZATION PLOTS AND JONES VECTOR VARIABLES

Periodic ports now create a new default Polarization plot. The Polarization plot depicts
the polarization state for the different diffraction orders and is based on new
postprocessing variables for Jones vectors elements. Also the base vectors, used for
defining the Jones vectors, are available for plotting and evaluation.
EVANESCENT WAVES INCLUDED IN THE PLANE-WAVE EXPANSION FORGAUSSIAN BEAM BACKGROUND FIELDS

When using the Plane wave expansion option for defining a Gaussian beam
background field, evanescent waves can also be included in the expansion. This option

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can be useful when simulating a tightly focused (spot radius smaller than the
wavelength) Gaussian beam propagating away from the focus.
REFERENCE POINT SUBFEATURE ADDED TO AND UPDATED FOR THE
SCATTERING CONDITION FEATUREThe Reference Point subfeature is now available for the Scattering Boundary
Condition feature for the Electromagnetic Waves, Frequency Domain interface when
an input field is active. The reference position is defined as the average position of theselected points. This feature is mainly useful when the domain material includes
absorption or gain.

New and Models in Version 5.5
SAR OF A HUMAN HEAD NEXT TO A WI-FI ANTENNA

Users of consumer electronics with radiating devices are exposed to radio frequency(RF) emission. The amount of exposure is defined as the specific absorption rate(SAR). That is, the SAR value represents the radio frequency (RF) energy rate
absorbed by a body. This model computes local SAR values over a simplified humanhead and brain mock-up when a microstrip patch antenna operating at the Wi-Fi
frequency range is placed close to the human head.
MIXED-MODE S-PARAMETERS ANALYSIS

Mixed-mode S-parameters describe the responses of a circuit with balanced ports
excited and terminated by two types of modes: common and differential modes. They
are calculated using a full S-parameter matrix of a four-port network that is composedof four single-ended lines. This example analyzes two adjacent microstrip lines andcomputes the mixed-mode S-parameters.
MODELING OF MICROSTRIP LINES WITH VIAS

There are multiple ways to excite and terminate transmission lines using different typesof port and lumped port features. In this example, transverse-electromagnetic (TEM)
type ports and a via-type lumped port are used to simulate two adjacent microstrip
lines. One via end is terminated as a metalized via while the other via end is probing
an inflow signal. The computed S-parameters show the amount of crosstalk between
the lines and the strength of the signal coupled through the cylindrical via.

160 |CHAPTER 1: RELEASE NOTESRotordynamics Module
New Functionality in Version 5.5
MULTI-SPOOL BEARING

Using the new feature Multi-Spool Bearing, it is possible to model vibrations in coaxial
rotors running at different speeds. This feature models the intershaft bearing between
two coaxial shafts. Such rotors are common in steam turbines in power plants, where
the system consists of a sequence of turbines having coaxial rotors running at different
speeds. Another example of multispool rotors is in turbofan engines, where an innershaft having a low-pressure turbine drives the fan, and an outer shaft having a highpressure turbine drives the compressor.
SQUEEZE FILM DAMPER

Squeeze film dampers are components that provide additional damping to rotating
systems through squeezing of the fluid film. Often, these components are used
together with rolling element bearings, which do not offer enough damping on theirown. Fluid film dampers are, however, also used together with hydrodynamic bearings.
There are two ways to model squeeze film dampers:• By solving Reynolds equation for the pressure distribution in the film, thus
computing the net reaction forces and moments of the damper. For this type ofmodeling, the new feature Squeeze Film Damper is provided in the Hydrodynamic
Bearing interface.
• By using an analytical expression for the forces and moments of the damper
obtained using the short length approximation. For this type of modeling, you can
add a Squeeze Film Damper subnode to the Journal Bearing and Radial Roller Bearing
nodes in the Solid Rotor and Beam Rotor interfaces.
DYNAMIC COEFFICIENTS CALCULATION FOR HYDRODYNAMIC BEARINGS

Dynamic coefficients (that is, equivalent linear stiffness and damping coefficients about
an equilibrium location of the journal) can now be computed. The computation isenabled by selecting Calculate dynamic coefficients in the settings for the Hydrodynamic
Bearing interface. This is useful for bearing design where it is necessary to limit thecross-coefficients in the bearing to avoid instability. Also, dynamic coefficients can beused to run simplified rotor simulations to speed up the process.

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DEFAULT GEOMETRY PLOT FOR BEAM ROTOR INTERFACEA new default plot for the geometry of the rotor has been added in the Beam Rotor
interface. This helps in visualizing the location of the various components while
analyzing the results.
• A disk is shown as a thin circular plate.
• A radial bearing is shown as a cone in the radial direction pointing toward the rotor.
• Axial bearings at the end of the rotor are represented by cones in the axial direction.
If an axial bearing is located at the interior of the rotor, a small disk representing thecollar of the bearing is drawn together with two cones pointing toward the collar
from both sides.
There is also an option in the interface settings to include this graphical representationin the stress and whirl plots.
CHANGE ROTOR SPEED FEATURE IN BEAM ROTOR INTERFACEA new feature, Change Rotor Speed, has been added to the Beam Rotor interface toallow modeling multispool rotors that are running at different angular speeds.
FILM BOUNDARY CONDITION IN HYDRODYNAMIC BEARING

When cavitation is not modeled in detail, a new section, Film Boundary Condition, isadded for Hydrodynamic Journal Bearing, Floating Ring Bearing, and Hydrodynamic Thrust
Bearing nodes. There are two options: Sommerfeld and Gümbel. The Sommerfeld
condition works as before, so that the full film is used for the net force computation.
The Gümbel condition considers only the part of the film where the pressure is positive
for the net force computation. This facilitates approximate modeling of the cavitation
effect in the film.
AUTOMATIC SETTINGS FOR CAMPBELL PLOTIn earlier versions, to get the proper Campbell plot, it was necessary to select the Axis
Source Data as Outer solution for all the nodes in the Campbell plot manually. This is
now handled automatically and no further manual settings are needed to get a proper
Campbell plot.
FATIGUE ANALYSIS IN SOLID ROTOR INTERFACEIn the Fatigue interface, it is now also possible to perform fatigue analysis based on
results from the Solid Rotor interface. Fatigue analysis requires the Fatigue Module.

162 |CHAPTER 1: RELEASE NOTESNEW POSTPROCESSING VARIABLES IN HYDRODYNAMIC BEARING
INTERFACE

Several new postprocessing variables have been added in the Hydrodynamic Bearing
interface and are available in the results menus. These variables include minimum film
thickness, maximum pressure, total viscous heat loss, journal eccentricity, journal
relative eccentricity, and attitude angle.

New Models in Version 5.5
CRITICAL SPEED OF A DUAL ROTOR SYSTEM

An eigenfrequency analysis of a dual rotor system connected through a multispool
bearing is performed in this model. Cross-exciting vibrations through the multi-spool
bearings make the dynamic behavior of one shaft dependent also on the dynamic
behavior of the other. Computed critical speeds are compared with values given in theliterature.
EVALUATION OF THE DYNAMIC COEFFICIENTS OF A PLAIN JOURNAL
BEARING

When analyzing rotors, it is common that bearings are modeled through their effective
dynamic coefficients about a static equilibrium position. This example demonstrates
how to compute such coefficients for a plain journal bearing. Computed coefficientsare also compared with analytical values obtained from the solution of the Reynolds
equation for a short bearing approximation.
DAMPING COEFFICIENTS OF A SQUEEZE FILM DAMPER

Squeeze film dampers are components that provide additional damping to rotatingmachines. To simplify the modeling of a rotor assembly, squeeze film dampers are often
modeled in terms of their damping coefficients. In this model, damping coefficientsare computed for a short squeeze film damper and compared to analytical values.
SHAFT VIBRATION DUE TO GEAR RATTLE AND BEARING MISALIGNMENT

In a gearbox, vibrations due to rattling of the gears and bearing misalignments are
well-known sources of noise. In this example, two shafts connected through a pair ofgears are considered. The driver rotates at varying speed. Due to backlash in the gears,
the teeth meshing becomes intermittent, thus causing vibration in the shafts. Aftersome time, the driven shaft is loaded with a torque, making the teeth meshing in gears
smooth. In order to analyze the effect of the misalignment on the rotor vibrations, atime-dependent analysis is performed for two cases. In the first case, all bearings are

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aligned with the shafts, and in the second case, one of the bearings has a small angular
misalignment. The results show larger torsional and axial vibrations in the shaft in thepresence of misalignment.

164 |CHAPTER 1: RELEASE NOTESSemiconductor Module
New Functionality in Version 5.5
DENSITY-GRADIENT FORMULATION

A new discretization option based on the density-gradient theory is introduced toinclude the effect of quantum confinement in the conventional drift-diffusion
formulation. This provides an efficient alternative to other more sophisticatedquantum mechanical methods, which are computationally expensive.
TRAP-ASSISTED HETEROINTERFACE RECOMBINATION

A new boundary condition is added for simulating the effects of interface traps atheterojunctions. It is straightforward to set up discrete and/or continuous energy leveltraps to account for their carrier capture and charging effects on heterointerfaces.
USER-DEFINED JUNCTION CURRENT

A new option for the heterojunction boundary condition allows the user to specify any
arbitrary current density at the junction.
TRAP QUASI-FERMI LEVEL FORMULATION

A new formulation for explicit traps is introduced to use the trap quasi-Fermi level as
the dependent variable to be solved for.
DOPING-DEPENDENT MATERIAL PROPERTIES

Acceptor concentration and donor concentration are now available under theTransport branch of the Model Input lists to facilitate the construction of dopingdependent material properties.
SOLID MECHANICS COUPLING

The variable for the time derivative of the displacement field is updated to allow meshdeformation for coupling to solid mechanics.
SCHRÖDINGER-POISSON EQUATIONThe range of weights for the Schrödinger-Poisson multiphysics coupling is extended
from 20 kT to 40 kT to cover cases with higher temperature ranges.

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NEW BUILT-IN FUNCTIONSNew Fermi-Dirac functions log_FD_half_inv_an and log_FD_half_an are available
to offer a full input argument range.
ACCURACY IMPROVEMENTS

The Caughey-Thomas Mobility Model formulation is updated to improve accuracy.
Default solver settings for time-dependent studies are updated for better accuracy.
Default scaling for quasi-Fermi level formulations are updated for better accuracy.
MODEL UPDATEThe mosfet_mobility tutorial model has been updated with the list of swept values
optimized for the continuation parameter of the field-dependent mobility models. An
unnecessary value is removed from the list to make the model solve faster and the filesize smaller.
CORRECTIONS AND BACKWARD COMPATIBILITY• An error in the time-dependent weak term for the quasi-Fermi level formulation has
been fixed since 5.4 update 3.
• A missing effect of explicit surface trap charges on Schottky contacts is fixed.
• The boundary current density formula between two adjacent Semiconductor
Material Model features is corrected for the finite volume discretization.
• The selection filter for the Zero Charge boundary condition is fixed to not override
the Axial Symmetry boundary condition.

New Models in Version 5.5
DENSITY-GRADIENT AND SCHRÖDINGER-POISSON RESULTS FOR A SI
INVERSION LAYERThis tutorial demonstrates the use of the density-gradient formulation to include theeffect of quantum confinement in the device physics simulation of a silicon inversion
layer. This formulation requires only a moderate increase of computational resources
as compared to the conventional drift-diffusion equation. Thus it allows much speedierengineering investigation than other more sophisticated quantum mechanicalmethods. The result of the density-gradient theory is compared with the solution of
the Schrödinger-Poisson equation. The computed electron density profiles from both

166 |CHAPTER 1: RELEASE NOTEStheories show the expected behavior of quantum confinement and both agree wellwith the published figures in the reference paper.
DENSITY-GRADIENT ANALYSIS OF AN INSB P-CHANNEL FETThis tutorial analyzes the DC characteristics of an InSb p-Channel FET, using thedensity-gradient theory to add the effect of quantum confinement to the conventional
drift-diffusion formulation without a large increase of computational resources. The
confinement effect is applied both in the quantum well channel and on the top
insulator interface, which is close to the channel. The use of an anisotropic densitygradient effective mass matrix is demonstrated, as well as the technique to configure ageneral field-dependent mobility model. The hole density profile and the Id-Vg curve
obtained from the 2D model compare well with the published figures in the reference
paper.
3D DENSITY-GRADIENT SIMULATION OF A NANOWIRE MOSFET

This 3D model of a nanowire MOSFET employs the density-gradient theory to add
the effect of quantum confinement to the conventional drift-diffusion formulation,
without requiring excessively high computational costs. The oxide layer is simulated
explicitly with geometric domains, and quantum confinement at the silicon-oxideinterface is accounted for via a dedicated boundary condition. The density-gradienteffective mass is anisotropic. Various selection utilities are used to simplify theassignment of physics settings and plot selections. The result matches well with the IdVg curves and electron density profiles published in the reference paper.
RADIATION EFFECTS IN A PIN DIODE

This tutorial performs steady-state and transient analyses of the response of a PIN
diode to constant and pulsed radiation, respectively. The effect of radiation is modeled
as a spatially uniform generation of electron-hole pairs within the device. At high dose
rates, the separation of the generated charges causes the reduction of the interior
electric field and prolonged storage of excess carriers. A quantitative prediction of thisphenomenon is only possible with numerical simulation, since an analytical solution isunattainable. Several techniques for achieving convergence in the cases of high reverse
bias, field-dependent mobility, and time-dependent studies are demonstrated. The
computed carrier concentrations and electric field distribution agree well with thereference paper.

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Structural Mechanics Module
New Functionality in Version 5.5
RANDOM VIBRATION ANALYSIS

Functionality for random vibration analysis has been added. This type of analysis isintended for situations where the load on a structure is random, but has well-defined
statistical properties that do not change with time. The excitation is described by its
power spectrum density (PSD). If there are several sources of excitation, also crosscorrelation spectra are needed. The output of the analysis is the PSD or RMS of any
linear expression.
In the Add Study dialog, the new study type Random Vibration (PSD) is available. Whenselected, a set of three different studies is added to the model. Also, three nodes are
created under Global Definitions->Reduced-Order Modeling for specifying the spectra.
STUDIES FOR REDUCED-ORDER MODELS

Three new studies for generation and simulation of reduced-order models (ROM)have been added to the Add Study dialog:• Time Dependent, Modal Reduced-Order Model• Frequency Domain, Modal Reduced-Order Model• Time Dependent, AWE Modal Reduced-Order Model
When one of these studies is selected, a set of two or three different studies is added
to the model. Also, two nodes are created under Global Definitions->Reduced-Order
Modeling for providing the input to the ROM.
The old study Modal Reduced-Order Model has been removed from the Add Study dialog.
It has been superseded by the more general Time Dependent, Modal Reduced-Order
Model. It is, however, still possible to add a Modal Reduced-Order Model study step
directly in the solver sequence if you want to access the old functionality.
IMPROVEMENTS IN CONTACT MODELINGThe contact modeling functionality has been extended and improved in many aspects.
• You can now model contact in all structural mechanics interfaces that are defined on
domains or boundaries: Solid Mechanics, Shell, Layered Shell, Membrane, and

168 |CHAPTER 1: RELEASE NOTESMultibody Dynamics. In the shell interfaces, thickness and offset are taken into
account.
• Contact can occur between two different physics interfaces.
• Contact can be modeled from one physics interface toward any meshed surface,even if that surface does not have any physics interface at all defined. This approachis particularly useful when modeling contact with a rigid shape.
• The more robust penalty method has replaced the augmented Lagrangian method
as the default contact algorithm.
• The friction forces are now represented in a boundary coordinate system. As aneffect, the number of friction degrees of freedom when using the augmented
Lagrangian method is now two in 3D (previous version: three) and one in 2D(previous version: two).
• Adhesion and Decohesion are now two separate subnodes under Contact.
• When using Adhesion, the adhesive layer stiffness can now also be given using elastic
material data by setting Adhesive stiffness to Use material data.
• In Decohesion, there are now new energy-based damage models. Also, you can now
include a viscous regularization in time-dependent analysis in order to mitigate theinherent instable behavior when the material is losing stiffness.
• New default plots showing arrows for contact pressure and friction force are
generated when a Contact node is present.
• The selection of pairs in the Contact node is more intuitive.
In a model created in a previous version, the old type of Contact node will still be kept.
If you add another Contact node, it will be of the new type.
NEW MULTIPHYSICS INTERFACES FOR THERMAL STRESS ANALYSIS

Three new multiphysics interfaces for thermal stress analysis have been added:• The Thermal Stress, Shell interface couples a Heat Transfer in Shells interface with a
Shell interface.
• The Thermal Stress, Layered Shell interface couples a Heat Transfer in Shells interface
with a Layered Shell interface. This interface is only available with the Composite
Materials Module.
• The Thermal Stress, Membrane interface couples a Heat Transfer in Shells interface
with a Membrane interface.

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In all three cases, the connection is made using the Layered Thermal Expansion
multiphysics coupling. This means that the Layered Linear Elastic Material is used in the
Shell and Membrane interfaces. The Layered Thermal Expansion multiphysics coupling
can also connect to a Thin Layer feature in the Heat Transfer in Solids interface.
As an effect of this, the old Thermal Stress multiphysics interface has been renamed to
Thermal Stress, Solid. All four thermal stress interfaces now reside in a group named
Thermal Stress in the Add Physics dialog.
NEW MULTIPHYSICS INTERFACE FOR FLUID-STRUCTURE INTERACTION
WITH HEAT TRANSFER

In some fluid-structure Interaction (FSI) problems, heat transfer between the fluid andthe solid is important. Usually, this is also accompanied by thermally induced
deformations or stresses in the solid. A new multiphysics interface, Fluid-Solid
Interaction, Conjugate Heat Transfer has been added in order to facilitate a convenient
setup of models combining these effects. It combines three physics interfaces, Heat
Transfer in Solids and Fluids, Solid Mechanics, and Laminar Flow, together with amoving mesh and appropriate multiphysics couplings. As with all other FSI interfaces,
the flow can be changed to turbulent if appropriate licenses are available.
FLUID-STRUCTURE INTERACTION FOR TWO-PHASE FLOWSIn the Add Physics dialog, two new multiphysics interfaces for two-phase flows havebeen added: Fluid-Solid Interaction, Two-Phase Flow, Phase Field and Fluid-Solid
Interaction, Two-Phase Flow, Phase Field, Fixed Geometry. These interfaces require also alicense that contains the underlying two-phase flow interfaces; that is, the CFD
Module or the Microfluidics Module.
PIPE MECHANICS INTERFACEThe new Pipe Mechanics interface is intended for structural analysis of pipes. Theinterface is, in many respects, similar to the Beam interface, with important
modifications necessary for the analysis of pipes. For instance:• Stresses, strains, and axial deformations caused by internal overpressure are taken
into account.
• The default material model is Fluid and Pipe Materials, reflecting that both thematerial in the pipe wall and the fluid are important.
• The Pipe Cross Section node has more and slightly different input parameters whencompared to the corresponding Cross Section Data node in the Beam interface.

170 |CHAPTER 1: RELEASE NOTES• A special type of load, Fluid Load, is included. There, you enter pressure and dragforces. These values can be taken directly from a Pipe Flow interface.
• A temperature gradient can be present through the pipe wall in the Thermal
Expansion node. The value can be taken directly from a Heat Transfer in Pipes
interface.
The Pipe Mechanics interface requires the Structural Mechanics Module or the Pipe
Flow Module.
ELASTIC WAVES, TIME EXPLICIT INTERFACEThe new Elastic Waves, Time Explicit interface makes it possible to analyze transient
wave propagation problems in linear elastic materials under small deformations in acomputationally efficient manner. In the Add Physics dialog, this interface is foundunder Elastic Waves in the Acoustics branch.
When the Acoustics Module is available, there is also a new multiphysics interface,
Acoustic-Solid Interaction, Time Explicit, which combines an Elastic Waves, Time Explicit

interface in solid domains with a Pressure Acoustics, Time Explicit interface in adjacent
acoustic domains.
NONRIGID JOINTS BETWEEN BEAMS

In the Beam interface, it is now possible to specify that two or more edges that meetin a point have disconnected degrees of freedom. This can, for example, be used formodeling internal hinges in a frame. To do this, you add a Beam End Release node andselect the common point, as well as the degrees to be disconnected. If there are morethan two beams attached to the point, you may also add one or more Edge Groupsubnodes to control the structure of the connection.
SOLID MECHANICS ON ROTATING DOMAINS

When modeling multiphysics problems in systems where there is a mixture of rotating
and stationary domains, it is now possible to use the Solid Mechanics interface in a
corotating configuration, so that only the deformations relative to the rotation aremodeled. This is far more efficient than solving for the total displacements including
large global rotations. To this end, the Rotating Frame feature has been extended sothat it can provide a superposition of the rigid body rotation and the relative
displacements for controlling the spatial frame.
DIRECT STIFFNESS INPUT FOR SHELLS AND PLATESIn the Shell and Plate interfaces, it is now possible to describe the elastic stiffness of across section directly in terms of membrane and bending stiffness, rather than by

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material data and thickness. This facilitates modeling of homogenized complex
structures, such as corrugated sheets.
EXTENSIONS OF LINEAR ELASTIC MATERIAL MODEL IN SHELL
INTERFACE

In version 5.5, the Layered Linear Elastic Material is present without the Composite
Materials Module license. This license is however still needed in order model
multilayered shells. The ability of this material model to handle more general throughthickness stress distribution does, however, make it important also for single-layershells.
Through the Layered Linear Elastic Material, several new materials models have been
implemented. Viscoelasticity is present in the Structural Mechanics Module, and withthe addition of the Nonlinear Structural Materials Module, there are also several
nonlinear material models such as plasticity.
There are also several new multiphysics couplings implemented through the Layered
Linear Elastic Material.
NEW LAYERED LINEAR ELASTIC MATERIAL IN THE MEMBRANE
INTERFACE

A new material model, the Layered Linear Elastic Material, has been added to theMembrane interface. With the Composite Materials Module license, it can be used tomodel multilayered thin films.
There are several material models that can be used together with the Layered Linear
Elastic Material — for example, viscoelasticity and plasticity. The nonlinear material
models require the Nonlinear Structural Materials Module. Since these material
models are already also available with the standard Linear Elastic Material, the main use
is for multilayered membranes.
SHELL DATASET FOR 2D AXISYMMETRY

The Shell dataset, by which a shell can be displayed by its top and bottom surface, is
now available also in 2D axisymmetry.
POINT SELECTIONS IN RIGID CONNECTOR FOR SHELL

The selection in a Rigid Connector in the Shell interface can now be a combination ofedges and points. It is also possible to add a rigid connector that is connected only toa set of points by adding it at the point level.

172 |CHAPTER 1: RELEASE NOTESNEW DEFAULT SCALE FACTOR FOR EIGENMODES

In the Eigenvalue Solver node within the solver sequence, a new option for scaling
eigenmodes has been added. This option is now used by all structural mechanics
interfaces to ensure that eigenmode amplitudes are small relative to the size of thegeometry. By doing this, it ensures that variables that are nonlinear by their nature will
be evaluated using small perturbations to the original geometry.
MODAL PARTICIPATION FACTORS TABLE

If a Participation Factors node is present under Definitions when an eigenfrequency
study is run, an evaluation group named Participation Factors is automaticallygenerated. It contains a table with the translational and rotational participation factors
for all computed eigenfrequencies.
NEW DEFAULT FOR TEMPERATURE DEPENDENT PROPERTIES

When material properties have a temperature dependence, the default in the Model
Inputs section is now to take the temperature from Common model input. In versions

prior to 5.5, the default was User defined. In both cases, the default temperature isroom temperature, as long as temperatures are not computed by another physics
interface. With the new formulation, the temperature will automatically be picked up
if defined under Default Model Inputs, for example, by a Heat Transfer in Solids
interface. The settings used in a model created in an earlier version are not affected.
TEMPERATURE COUPLING NODE IS OBSOLETE

The Temperature Coupling multiphysics node is no longer used for the transfer oftemperatures from heat transfer interfaces to structural mechanics interfaces. Instead,the common model input mechanism is used for transferring the temperature. Inmodels created prior to version 5.5, the Temperature Coupling node is still present andused. A warning message is, however, shown.
In all nodes where temperature-dependent properties are referenced, the default value
for the temperature in the Model Inputs section is now Common model input.
SYNCHRONIZATION OF ELASTIC PROPERTIES

If isotropic material data (for example, E and ν) are present in a Material, then thismaterial can also be used if the Solid model in a linear elastic material is set to
Orthotropic or Anisotropic. Similarly, orthotropic material data can be used when Solidmodel is set to Anisotropic.

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ENHANCEMENTS FOR CELL PERIODICITYThe Cell Periodicity node in the Solid Mechanics interface has a number of
improvements:• It is now available also in 2D. If the generalized plane strain formulation is used,then it is also possible to generate a global Material node, in the same manner as in
the 3D case.
• One separate global Material node is created for each Cell Periodicity node. This
makes it possible to evaluate several RVE cells in the same study.
• When using Cell Periodicity, a default evaluation group is generated for displaying thecomputed material properties. This group contains a Global Matrix Evaluation node
where the elasticity or compliance matrix is shown.
• The Create button has been replaced by icons in a section toolbar and split into
separate operations for study generation and material node generation.
MAGNETOSTRICTION WITH MAGNETIC HYSTERESISThe Magnetostrictive Material has been extended to include the Jiles–Atherton model
for magnetic hysteresis.
USER-DEFINED MATERIAL FOR MEMBRANESThe External Stress-Strain Relation material model has been added also to theMembrane interface. With this material model, you can add your own material models,
coded in C or other programming languages.
ENHANCEMENTS FOR EXTERNAL MATERIALSWhen implementing your own material using External Stress-Strain Relation or External
Strain, you can now pass back your own warning and log messages, which are displayedin the GUI.
Another improvement is that the limit for the number of parameters that can be passed
to an external material has been increased significantly.
When using the External Stress-Strain Relation for a plane stress Solid Mechanics
interface in 2D, additional degrees of freedom for the transverse shear strains can be
activated by selecting the Allow transverse shear strains check box. This is needed forsome type of anisotropies in the material model.
IMPROVED SYMMETRY AND ANTISYMMETRY FOR MEMBRANE

In the Symmetry and Antisymmetry nodes in the Membrane interface, a new Face
Defining the Local Orientations section has been added. The purpose is to define a174 |CHAPTER 1: RELEASE NOTES

unique orientation of the symmetry plane in cases where several boundaries areattached to the selected edge.
SUPPORT FOR GENERAL ANISOTROPY IN MEMBRANE INTERFACE

The anisotropic version of the Linear Elastic Material in the Membrane interface can
now include also terms coupling transverse shear to in-plane behavior.
THIN ELASTIC LAYER WITH MASSIn the Thin Elastic Layer node in the Solid Mechanics interface, it is now also possible
to assign a mass distribution to the layer. This mass is taken into account both indynamic analysis and in loads from gravity and rotating frames.
UPDATED COUPLING BETWEEN SOLIDS AND THIN STRUCTURESThe Solid-Shell Connection multiphysics coupling has been renamed Solid-Thin Structure
Connection in order to reflect that it now also supports couplings to the Membraneinterface. There are also some minor changes to the GUI of the coupling.
COROTATING LOADS ON RIGID DOMAIN

When applying loads in a Rigid Domain node through the Applied Force subnode, it is
now possible to specify that the load direction follows the rotation of the body. The
new Direction setting has two options: Space-fixed direction and Body-fixed direction.
DEFAULT LOAD PLOTS

All structural mechanics interfaces will generate default vector plots of applied loads.
By running Get Initial Value, you can get such plots generated for checking input data.
During result evaluation, the load plots will display the loads corresponding to thecurrent time or parameter value.
The load plots use standard plot types under Results. The options are chosen so thatyou can easily customize the plots to get a good visual impression.
As part of this project, new variables containing the loads are defined in all loadfeatures. These variables have names that are unified between all load features in all
structural mechanics interfaces. Any old variables are still available for backward
compatibility, with one exception: the variable solid.Fp, which was defined by the
Point Load node. Any expression in an existing model containing, for example,
solid.Fpy, must be replaced by solid.F_Py.

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NEW SETTINGS FOR ROLLER IN SOLID MECHANICS

The settings in the Roller Constraint section in the Roller node have been changed for2D and 2D axisymmetry in order to reflect the limitations and interpretations that therespective space dimensions impose.
THERMAL BENDING FOR LAYERED LINEAR ELASTIC MATERIAL IN THE
SHELL INTERFACEIn the Thermal Expansion subnode under the Layered Linear Elastic Material in the Shellinterface, it is now also possible to enter a through-thickness temperature difference ortemperature gradient. This will generate bending thermal strains.
HYGROSCOPIC BENDING FOR LAYERED LINEAR ELASTIC MATERIAL IN
THE SHELL INTERFACEIn the Hygroscopic Swelling subnode under the Layered Linear Elastic Material in the
Shell interface, it is now also possible to enter a through-thickness concentrationdifference or concentration gradient. This will generate bending hygroscopic swellingstrains.
LOCAL EDGE SYSTEM FOR BOUNDARY CONDITIONS IN THE MEMBRANE
INTERFACE

For boundary conditions applied to edges in the Membrane interface, it is now possible
use also a local edge system for defining the orientation. The following boundary
conditions are affected: Edge Load, Prescribed Displacement, Prescribed Velocity,
Prescribed Acceleration, Spring Foundation, and Added Mass.
IMPROVEMENTS FOR SHELL LOCAL SYSTEM IN 2D AXISYMMETRY

The Shell Local System node now has a Coordinate System Selection section also in 2D
axisymmetry. Only boundary systems can be selected. The main purpose is to accessthe option to flip the normal orientation that exists in a boundary system.
The Shell Local System node has also been added to the Rigid Domain material model in
2D axisymmetry.
WAVE SPEED COMPUTATION IN ELASTIC MATERIALSFor the Linear Elastic Material and Piezoelectric Material, it is now possible to computewave speeds for elastic waves. To do that, add the Wave Speeds node, available under
Variables in the context menu for the material models or under Attributes on the ribbon
when the material model is selected.

176 |CHAPTER 1: RELEASE NOTESThe effect of this node is to make variables for phase and group velocities for elastic
waves available for result presentation. The solution as such is not affected, and thevariables will be available for any study type.
DISPLAY OF NORMAL DIRECTIONS IN SHELL AND MEMBRANE
INTERFACES

When physics symbols are switched on in the Shell or Membrane interface, and amaterial model node is selected in the Model Builder, a green arrow will indicate thepositive normal direction for each boundary.
SAFETY MOVED IN CONTEXT MENUS

The Safety feature, which is available for many material models in various physics
interfaces, has been moved in the context menu. When right-clicking on a material
model, you will now find it under a subfolder called Variables.
DEFAULT PLOTS GENERATED BY SAFETY NODE

When you add a Safety node in one of the Shell, Layered Shell, or Membraneinterfaces, a default plot with the failure index is generated. Such plots are placed in agroup named Failure Indices. The label of these plots is derived from the label of thecorresponding Safety node.
NEW GROUPING OF DEFAULT PLOTS IN BEAM INTERFACEAll default plots of section forces in the Beam interface are now placed inside a groupnamed Section Forces in order to reduce the number of result nodes that are directly
visible.
DEFAULT PLOTS FILTERED BY ACTIVATION STATUS

When an Activation node is present, the default surface plots will get a Filter subnode.
The filter serves the purpose of suppressing the plotting of domains not currently
activated.
BACKWARD COMPATIBILITY DISCONTINUED FOR PRE-4.4 BEAM
INTERFACE

The Backward Compatibility section in the settings for the Beam interface has been
removed. It is no longer possible to open models containing a Beam interface built inversions earlier than 4.4. If you need to convert such models, open them in any version
between 4.4 and 5.4 and convert to the more recent formulation.

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ERROR AND WARNINGS IN EXTERNAL MATERIALSWhen programming your own constitutive relations using the external materials
functionality, certain code segments might return errors or warnings. The generalstress-strain relation, the general stress-deformation relation, the inelastic residualstrain, and the inelastic residual deformation now include the possibility to add anargument to return detailed internal error messages and to display warnings in thesolver log.

New Models in Version 5.5
EIGENMODES OF A VISCOELASTIC STRUCTURAL DAMPER

In this model, methods for performing eigenfrequency analysis of materials withfrequency-dependent material properties are explored. In this situation, the eigenvalue
problem becomes nonlinear. In the example, model methods are used for finding the
eigenfrequencies one-by-one.
BIMETALLIC STRIP IN AIRFLOWThis is a conceptual model illustrating how to couple fluid-structure interaction, heattransfer, and thermal expansion. The new Fluid-Solid Interaction, Conjugate Heat
Transfer multiphysics interface is used. A bimetallic strip in an air channel is heated sothat it bends. After some time, an airflow with an inlet temperature that varies in timeis introduced. As a result, there are changes in deformation caused both by the fluidpressure and by the convective cooling.
TWO-PHASE FLOW WITH FLUID-STRUCTURE INTERACTION

This example demonstrates techniques for modeling a fluid-structure interaction
containing two fluid phases in COMSOL Multiphysics. It illustrates how a heavier
fluid can induce movement in an obstacle using the arbitrary Lagrangian-Eulerian(ALE) technique. The Fluid-Solid Interaction, Two-Phase Flow, Phase Field is used.
COUPLED ANALYSIS OF FLOW AND STRESS IN A PIPE

In this tutorial model, the flow in a pipe with a bend is computed using the Pipe Flowinterface. The computed fluid load is used as input to a stress analysis in the Pipe
Mechanics interface. Gravity loads from the pipe and fluid are also taken into account.
Running the full example requires the Pipe Flow Module.

178 |CHAPTER 1: RELEASE NOTESSENSITIVITY ANALYSIS OF A TRUSS TOWER

Sensitivity analysis is an efficient way of computing the gradient of an objectivefunction with respect to many control variables. This example uses the pitch and yaw
in the top of a truss tower as objective functions. It shows how to compute thesensitivity of these angles with respect to changes in the individual truss member
diameters.
BRACKET — TOPOLOGY OPTIMIZATIONThis example shows how to perform a topology optimization with several load andconstraint cases. The density feature for topology optimization is used together with aparametric sweep where each optimized solution is used as input for a further
improved optimization. The final optimized geometry is exported and then imported
for a verification analysis in which the now void domain is excluded.
BRACKET — RANDOM VIBRATION ANALYSISThis example shows how to perform a random vibration analysis of a structure using
power spectral density (PSD). The computations are based on the modal reducedorder model (ROM).
RANDOM VIBRATION ANALYSIS OF A DEEP BEAM

In this example, forced random vibrations of a simply-supported deep beam arestudied. The beam is loaded by a distributed force with a uniform power spectral
density (PSD). The output PSD is computed for the displacement and bending stressresponse. The computed values are compared with analytical results.
BLOCK PRESSING ON ARCH

This conceptual example shows how to calculate critical points in models with contact.
The model consists of a block modeled with the Solid Mechanics interface pressing on
an arch modeled with the Shell interface. The contact problem is solved using theaugmented Lagrangian method. The block is loaded with a displacement-controlled
boundary load and is incrementally pressed toward the arch. During loading, there isa snap-through behavior of the arch but the solution remains stable.
INSTABILITY OF TWO CONTACTING ARCHESThis is a benchmark example where instability is studied in a model with contact. Twocontacting arches are modeled in the Shell interface. The contact problem is solved
using the penalty method. The upper arch is loaded with displacement-controlled edge
loads and is pressed toward the lower arch. During loading, a snap-through behaviorof the lower arch is observed with several critical points related to sideways instability.

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In order to obtain a stable reference solution, the sideways movement of the mid edgeof both arches is constrained.
ISOTROPIC-ANISOTROPIC SAMPLE: ELASTIC WAVE PROPAGATIONIn this 2D tutorial model, a test sample consists on one side of an isotropic material
and on the other side of a heterogeneous anisotropic material (a transverse anisotropic
zinc crystal). Elastic waves in the sample are excited by a point-like force. The model
is solved with the Elastic Waves, Time Explicit physics interface.
GROUND MOTION AFTER SEISMIC EVENT: SCATTERING OFF A SMALL
MOUNTAIN

In this tutorial, the propagation of elastic waves in the ground after a seismic event issimulated using a 2D model. The effect of the ground surface topology on the wave
propagation is illustrated when an ideal half space is modified with the presence of asmall mountain. The model is a variation of Lamb’s problem. The propagation of theelastic waves is modeled using the Elastic Waves, Time Explicit physics interface and themodel captures the propagation and scattering of pressure waves, shear waves,Rayleigh waves, and von Schmidt waves.

Backward Compatibility with Version 5.2
The friction slip velocity is no longer defined as a dependent variable. When runninga model using the COMSOL API, you will need to remove the reference to thisvariable in the solver settings. The friction slip velocity is usually defined as<comp>_<solid>_vslip_<pairname>, where <comp> is the tag of the component,<solid> is the tag of the Solid Mechanics physics interface where the Friction node isdefined, and <pairname> is the name of the contact pair.

180 |CHAPTER 1: RELEASE NOTES

Subsurface Flow Module
New Functionality in Version 5.5• Ambient properties, such as temperature, relative humidity, absolute pressure, windvelocity, and solar irradiance, can be defined in the Ambient Properties node. Besidethe possibility to add user-defined meteorological data, two meteorological datasets
are available that contain ambient data from several weather stations in the world.
When transient studies are performed, the climate data is automaticallysynchronized. In addition, a new boundary condition is added to the Darcy’s Law
interface to account for the precipitation rate given in the Ambient Properties node.
• In the Brinkman Equations and Free and Porous Media Flow interfaces, the Porous
Matrix Properties section in the Fluid and Matrix Properties domain feature now
contains a Non-Darcian option in the drop-down list for the Permeability model. This
option also replaces the old Forchheimer Drag subfeature.
• In the Darcy’s Law interface, the Matrix Properties section in the Fluid and Matrix
Properties domain feature now contains a Non-Darcian option in the drop-down list
for the Permeability model. This can be used to add a Forchheimer drag term to themomentum equation. The Darcy’s Law interface also has a new setting, at theinterface level, for including gravity effects.
• The Inlet and Outlet boundary conditions in the Darcy’s Law interface have been
extended to include the possibility to specify the pressure and the mass flow in the
Inlet node, and the pressure in the Outlet node.
• New adsorption models for mass transport in porous media. The Toth and BET
models are now available in the Adsorption node.
NEW HEAT TRANSFER IN FRACTURES INTERFACEThe new Heat Transfer in Fractures interface models heat transfer in fractured porous
media. Using this interface prevents representing the fracture thickness in thegeometry. The interface provides a lumped model for cost-effective modeling, anddedicated settings to define the fluid and the material properties. The flow velocity inthe fracture can be taken from the Fracture Flow interface.
NEW REACTING FLOW IN POROUS MEDIA INTERFACEThe Reacting Flow in Porous Media, Transport of Diluted Species multiphysics interface isused to study the flow and chemical composition of a gas or liquid moving through

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the interstices of a porous medium. The multiphysics interface combines the Brinkman
Equations and Transport of Diluted Species in Porous Media interfaces. The Reacting Flow,
Diluted Species multiphysics coupling is added to couple fluid flow and mass transport.
The chemical species are assumed to be solutes dissolved in a solvent of significantly
higher concentration.

New Models in Version 5.5
FROZEN INCLUSION

This benchmark problem studies the melting process of an ice inclusion within aporous medium, and it demonstrates how to couple the Darcy’s Law interface with theHeat Transfer in Porous Media interface including phase change.

Backward Compatibility with Version 5.4
Models created using the Brinkman Equations and Free and Porous Media Flowinterfaces need to be modified if they apply Forchheimer drag. The previous subfeature
has been replaced by a new setting in the Porous Matrix Properties section.
Old Java files need to replace the line
model.component("comp1").physics("fp").feature("fmp1").
create("fd1", "Forchheimer", 2);withmodel.component("comp1").physics("fp").feature("fmp1").
set("ktype", "nonDarcianModel");Forchheimer is the default. Also replacemodel.component("comp1").physics("fp").feature("fmp1").
feature("fd1").set("betaF", "value");withmodel.component("comp1").physics("fp").feature("fmp1").
set("cf", "value");

Backward Compatibility with Version 5.3a and Earlier
NO FLUX FORMULATION

The formulation of the No Flux feature has been changed in the Transport of Diluted
Species and Transport of Diluted Species in Porous Media interfaces in version 5.4 so

182 |CHAPTER 1: RELEASE NOTES

that the flux relative to the convective flux is set to zero. The new formulation is used
when opening a model from a previous session. In the previous formulation, the total
flux was set to zero.

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Wave Optics Module
New Functionality in Version 5.5
COUPLING FROM FULL-WAVE TO RAY OPTICS SIMULATION

Two new features, Release from Electric Field and Release from Far-Field Radiation
Pattern, have been added to the Geometrical Optics interface in the Ray Optics
Module that either release rays based on a near- or far-field computed from a full-wave
simulation. The full-wave field can be produced by the Electromagnetic Waves,Frequency Domain and Electromagnetic Waves, Beam Envelopes interfaces in the
Wave Optics Module or the Electromagnetic Waves, Frequency Domain interface in
the RF Module.
GAUSSIAN BEAM INPUT OPTION FOR SCATTERING AND MATCHED
BOUNDARY CONDITIONSThe Scattering and the Matched boundary conditions have a new option for the
Incident field list. Choosing the Gaussian beam option allows you to propagate a
Gaussian beam into an arbitrary direction. The Gaussian beam is defined using theparaxial Gaussian beam formula.
POLARIZATION PLOTS AND JONES VECTOR VARIABLES

Periodic ports now create a new default Polarization plot. The Polarization plot depicts
the polarization state for the different diffraction orders and is based on new
postprocessing variables for Jones vectors elements. Also, the base vectors, used for
defining the Jones vectors, are available for plotting and evaluation.
EVANESCENT WAVES INCLUDED IN THE PLANE-WAVE EXPANSION FORGAUSSIAN BEAM BACKGROUND FIELDS

When using the Plane wave expansion option for defining a Gaussian beam
background field, evanescent waves can also be included in the expansion. This option
can be useful when simulating a tightly focused (spot radius smaller than the
wavelength) Gaussian beam propagating away from the focus.

184 |CHAPTER 1: RELEASE NOTESSLIT PORTS ARE AVAILABLE ALSO FOR THE UNIDIRECTIONALFORMULATION FOR THE ELECTROMAGNETIC WAVES, BEAM ENVELOPESINTERFACE

Slit ports are now available also for the Unidirectional formulation for theElectromagnetic Waves, Beam Envelopes interface. Slit ports can be useful if several
modes are propagating, but only the reflectance or transmittance of one of the modes
is of interest. Then, use a domain-backed slit port for the mode of interest and let therest of the modes be absorbed by a perfectly matched layer (PML) in the domain
behind the port.
REFERENCE POINT SUBFEATURE ADDED TO AND UPDATED FOR THE
SCATTERING AND MATCHED BOUNDARY CONDITION FEATURESThe Reference Point subfeature is now available in the Scattering and Matched
Boundary conditions for the Electromagnetic Waves, Frequency Domain andElectromagnetic Waves, Beam Envelopes interfaces, when an input field is active. The
reference position is defined as the average position of the selected points. This feature
is mainly useful when the domain material includes absorption or gain.
PORT UTILITY

Cutoff Frequency Calculator
A cutoff frequency calculator is available from the rectangular and circular port type
Setting windows. This helps to quickly identify the cutoff frequency for a given modein an arbitrary sized waveguide.
ADDITIONAL 3D FAR-FIELD FUNCTIONS FROM 2D AXISYMMETRICCOMPONENT MODEL

Effective 3D antenna gain and realized gain functions for 2D axisymmetric models areadded.
PHYSICS-CONTROLLED MESHING FOR PAIR FEATURES

The physics-controlled meshing algorithm now produces copied meshes for pairfeatures.

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New and Updated Models in Version 5.5
TOTAL INTERNAL REFLECTION

This model demonstrates that the bidirectional formulation of the Electromagnetic
Waves, Beam Envelopes interface can be used for simulating a beam being reflected in
two main directions as it propagates along a waveguide.
An almost collimated Gaussian beam is excited at the left boundary and exhibits totalinternal reflection (TIR) at the interface between the waveguide and the surrounding
air. The beam exits the waveguide after propagating along the waveguide for 20 mm.
This type of light guide is useful for virtual reality (VR) simulation.
ORBITAL ANGULAR MOMENTUM BEAM

This model simulates a Laguerre–Gaussian beam with the Electromagnetic Waves,Beam Envelopes interface, using the unidirectional wave formulation. The input beam
is a focusing Gaussian beam with a spiral phase distribution.
This phase distribution produces a Gaussian donut beam. The phase rotates around theoptical axis as the beam propagates. The resulting beam is called a vortex beam.
FREQUENCY-SELECTIVE SURFACE, PERIODIC COMPLEMENTARY SPLIT
RING RESONATOR

Frequency selective surfaces (FSS) are periodic structures with a bandpass or abandstop frequency response. This example shows that only signals around the center
frequency can pass through the periodic complimentary split ring resonator layer.
This model demonstrates the use of slit ports and shows how to use the Adaptive
Frequency Sweep study step.
DIRECTIONAL COUPLER

This model has been extended to include the following three parts:• Unidirectional propagation, showing basic modeling steps when using theElectromagnetic Waves, Beam Envelopes method. This part was available in 5.4.
• Bidirectional copropagation, showing that the mesh requirements can be reduced
by propagating the two modes using the bidirectional formulation. This part wasalso available in 5.4.
• Approximation of a target input field using overlap integrals for calculating theexciting ports’ input powers and mode phases. New in 5.5.

186 |CHAPTER 1: RELEASE NOTESThe model is also restructured to keep the physics interfaces, meshes, studies, and plotgroups for the three different modeling parts.
FOCUSING LENSThis model has been updated to use the Transition boundary condition to represent
an antireflection (AR) coating on the lens boundaries.
UPDATED MODELS

Application Library Paths for Models Using the New Gaussian Beam Input Option for
the Scattering and Matched Boundary Conditions• Wave_Optics_Module/Nonlinear_Optics/self_focusing• Wave_Optics_Module/Optical_Scattering/beam_splitter• Wave_Optics_Module/Optical_Scattering/brewster_interface

Application Library Paths for Models Using the New Polarization Plot
• Wave_Optics_Module/Gratings_and_Metamaterials/frequency_selective_surface_cs
rr• Wave_Optics_Module/Gratings_and_Metamaterials/hexagonal_gratings• Wave_Optics_Module/Verification_Examples/fresnel_equations

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Material Library
New and Updated Material Data in Version 5.5
In version 5.5, the following improvements have been made:• Surface tension data has been added to 115 datasets as SurfF for the surface tension
coefficient.
• The thermal conductivity for 304 stainless steel above room temperature wasrevised. Data from a new reference was added. The new values are the same as theold values near 20°C but are 35% lower at 600°C.
• The thermal conductivity for 316 stainless steel above room temperature wasrevised. Data from a new reference was added. The new values are within 5% of theold values at all temperatures.
• Data was added for several Kynar grades — 460, 710, 720, 740, and 760 — and forPebax.
• Data was added for E glass and S-2 glass fibers and for MgB2.
• Data was added for the C18150, ZEK100, CMSX-4, NARloy-Z, GRCop-84, Cu4Cr-2Nb, Fe-22Mn, Fe-24Mn, API X80, 1144, and 4142 alloys.
• Data was added for Bi2Te3 (n- and p-type).
• The elastic properties for Ti-6Al-4V and Inconel 718 were refit. The largest change
was in Poisson’s ratio. For 718, the change was a few percent. For Ti-6Al-4V, thechange was approximately 15% near room temperature and close to 0 at 930°C.
• Data was added for RAFM steel (9Cr-1W), 304L weld metal, CMSX-4, CMSX-10,
Thermo-Span alloy, PWA 1485, SRR99, MAR M247, and Rene 94.
• Data was added for H13, Zn-48Sb, Modified 9Cr-1Mo, A316, 5115 steel, API X60
steel, Mg-4Li, CRONIDUR 30, and 409 wire.
• Data was added for FGH96, ZK60, AZ91, AZ91 Be, AM60, AMZ40, AJ62,
Nitinol, CMSX-4, 25MnCrSiVB6, 50CrMo4 (4150), 100CrMnMoSi8, Ir, Rh, Pt
alloys, Sn-8Zn-3Bi,ScF3, SrF2, LaNbO4, propylene glycol, Li7Sn3, Li13Sn5,
Li7Sn2, Li17Sn4, and ZrB2-B4C-SiC.
• The reference “E.P. Papadakis, Materials Science and Engineering, v. 10, p. 195(1972)” was used for the expansion of several materials. This reference has been
replaced with new references for the affected materials: 317/317L, FS-85 (Nb28Ta-10W-1Zr), Cb-752 (Nb-10W-2.5Zr), Inconel 700, and ZrSiO4.

188 |CHAPTER 1: RELEASE NOTES• Data was added for Pt-10Rh, Pt-20Rh , P91, P92, 9 Cr - 1 Mo - V - Nb (T91),
Ferritic ductile iron (3.3 C - 3.25 Si - 0.13 Mn - 0.002 Ce), Inconel 617, 38MnVS& 25MnCrVS, ZrN, P4M, HT7, 5754, Cu, W-5Ni-2Fe, Nb-10Ti-5Zr, Nb-10W5Zr, Nb-5Mo-5V-1Zr, and Nb - 15 W - 5 Mo - 1 Zr.
• The reference for the thermal expansion of TZM was changed. The new values are
50% higher near room temperature and 10% higher at elevated temperatures.
• Data was added for Ti-1555A, Ti-150A, Ti-140A, C-130AM, AM60B and Inconel
617 welds.
• Data was added for the following acrylics: PLEXIGLAS G, PLEXIGLAS MC,
Perspex-CQ, Acrylite OP-1, and Solacryl 2750. The expansion data for the PMMA
was changed to be the average of these new acrylics.
• The reference for the vapor pressure of iron was corrected.
• The elastic properties of copper were extended from 300 K to 1330 K.
• Data was added for Invar, Ta, Nb-10W-5Zr, 304, and 1018, and for hydrocarbons
and molten salts (used for energy storage).

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LiveLink™ for MATLAB ®
New Functionality in Version 5.5
LiveLink™ for MATLAB® now supports MATLAB® 2019a and 2019b.
The following sections list new and improved functionality in LiveLink™ for
MATLAB®.
USER INTERFACES

The user interface mphnavigator has been updated with new functionality for updating
the properties and methods panes using a button on the toolbar.
There is a new tool for copying code to the clipboard that shows how to make a loop
for the currently selected node in the model tree. For a work plane, the copied code
may look like this:tag1 = 'geom1';
tag2 = 'wp2';
tags = cell(model.geom(tag1).feature(tag2).geom.feature.tags);
for i=1:length(tags)
obj = model.geom(tag1).feature(tag2).geom.feature(tags{i});endThis feature saves a lot of manual typing. The copied code can then be tailored to a
specific use and inserted in scripts and functions.
Mphmodellibrary, which is used to browse the Application Libraries, now also show
any user-defined libraries. You can add user-defined libraries using the COMSOLDesktop.
PLOTTING

The function mphplot has been updated to support new plot types added to
COMSOL 5.5.
Mphplot and other plotting function have improved support for plotting in windows
created by the App Designer, which uses uiaxes for plotting instead of the regular axes
objects in MATLAB figures and user interfaces created by GUIDE.
MPHGETADJ

An extra output has been added to mphgetadj:[n, m] = mphgetadj(model,geomtag,returntype,adjtype,adjnumber)

190 |CHAPTER 1: RELEASE NOTES

returns the indices of all the adjacent geometry entities in N. M contains the indices ofentities that connect the entities the best. The latter can be used to, for example,
extract edge entities that connect a certain set of points.
MPHMEASURE

Mphmeasure is a new function. It measures entities in a geometry.
[m1,m2]=mphmeasure(model,geomtag,entity,…)

Based on the entity, you can measure quantities such as distances, areas, and volumes
in a geometry.
MPHTABLE

This function now supports evaluation groups as well as tables.

Backward Compatibility with Version 5.4
Mphreduction has been changed in version 5.5 such that it no longer can be used todefine model reduction studies. You have to manually add the necessary studies to themodel. Mphreduction can then be used to extract the defined matrices for use in
MATLAB.

Backward Compatibility with Version 5.2
The functions mpheval, mphglobal, and mphinterp, which extract numerical data,
now support complex values by default; that is, the property 'complexout' is 'on' bydefault. If you want to have the previous behavior, set 'complexout' to 'off'.

Backward Compatibility with Version 5.0• The mphint2 command: For data sets other than Solution, Particle, Cut Line,
Cut Plane, Time Integral, Time Average, Surface, and Line, the integration order
now corresponds to the element refinement. The default value is set to 4 instead of
1. This change can affect the solution in cases where the problem is not resolved wellenough.

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The COMSOL API for Use with Java ®
COMSOL 5.4 API Changes
CAD IMPORT MODULE, DESIGN MODULE, AND LIVELINK PRODUCTS FORCAD CHANGESThe new fillholes property has been added for the Import function. The following
applies:• The combination of the fillholes property set to on and the knit property set tosolid is equivalent to the knit property set to solid in previous versions.
• The combination of the fillholes property set to off and the knit property set
to surface is equivalent to the knit property set to surface in version 5.3a.
• The combination of the fillholes property set to on and the knit property set tosurface is equivalent to the knit property set to surface in version 5.3 andprevious versions.
The new fillholes property has been added for the Knit function. The Knit
function with the fillholes property set to on corresponds to the Knit function inprevious versions.
ECAD IMPORT MODULE CHANGES• The properties selnetcontributetobnd, selnetcontributetodom,
selnetkeepbnd, selnetkeepdom, selnetnamebnd, selnetnamedom,selnetshowbnd, selnetshowdom, selnettagbnd, and selnettagdom have been
added to the Import function. The properties apply to the IPC-2581 and ODB++
file types and enable working with the selections generated for the electrical nets
found in the imported files.
• The elevation property of the Import function is now initialized when setting themanualelevation property to off. Previously, it was only initialized when setting
the filename property and when the manualelevation property is off and thevalue of either the height or importtype properties is changed.

192 |CHAPTER 1: RELEASE NOTESCOMSOL 5.3a API Changes
PARTITION OBJECTS PROPERTIESThe keep property has been deprecated in version 5.3a. Instead, use the newproperties keepinput and keeptool. If you set keep to on, both keepinput andkeeptool are set to on. If you get the value of keep, it is on if keepinput andkeeptool are on.

COMSOL 5.3 API Changes
NEW COMPONENT SYNTAXThe geometry component is now included in the code for features that appear in acomponent. For example,
model.geom("geom1")

in earlier versions is now instead
model.component("comp1").geom("geom1")

to indicate which component the geometry belongs to. To keep the old syntax ingenerated Model Java® files, clear the Use component syntax check box under Codegeneration on the Methods page in the Preferences window. All old scripts and Java®
source code files will continue to work using the old syntax.
ECAD IMPORT MODULE CHANGES• The default value for the sellayer property of the Import function is now on.
Previously, the default was off.
• The default value for the sellayershow property of the Import function is now
all. Previously, the default was dom.

COMSOL 5.2a API Changes
AC/DC MODULE CHANGESNew Coil Feature
In the Magnetic Fields, Magnetic and Electric Fields, and Rotating Machinery,
Magnetic interfaces, a new unified Coil feature has replaced the Multi-Turn Coil feature.
The functionality of the old Multi-Turn Coil feature can be replicated by using the new
Coil feature with the Conductor model set to Homogenized Multi-Turn, but all of the

THE COMSOL API FOR USE WITH JAVA®

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193

other parameters are unchanged. The only change required is to the create statements
such as:model.physics("mf").feature().create("mtcd1","MultiTurnCoilDomain", 3);

which should be modified to:model.physics("mf").feature().create("mtcd1", "Coil", 3);model.physics("mf").feature("mtcd1").set("ConductorModel","Multi");

User-Defined Coil Geometry Subfeature Selection
In 3D models, when using a user-defined geometry for a Coil feature, the User Defined
Coil Geometry subfeature has been transformed from a boundary feature to a domainfeature. New Input and Output subnodes are used to select the coil input or output
boundaries instead. Any code setting the selection of this feature should be modified
to set the selection on the Input subfeature instead.

Relative Permeability for Magnetic Shielding in Magnetic Fields, No Current
The relative permeability parameter mur in the Magnetic Shielding feature in the
Magnetic Fields, No Currents interface is now a scalar quantity. Setting a tensor
quantity will not cause exception, but only the first component of the tensor will be
used as the value.
ACOUSTICS MODULE CHANGESThe default settings have changed for the Incident Pressure Field in the Pressure
Acoustics interfaces. Add the following line to obtain the old behavior of this featurewhen ipf1 is a subfeature to pwr1:
model.physics("acpr").feature("pwr1").feature("ipf1").
set("c", "acpr.c_c");

COMSOL 5.1 API Changes
ACOUSTICS MODULE CHANGESThe ratio of specific heats is now a material parameter. If the default value was used ina model, add the following line to the Java® file to obtain the old behavior:model.physics("cpf").feature("cpf1").set("gamma_mat", "userdef");

194 |CHAPTER 1: RELEASE NOTESELECTROCHEMISTRY MODULES CHANGES

There are changes for the Tertiary Current Distribution, Nernst-Planck interface. The
Java® API syntax for creating and accessing vectors and tensors has changed, as well as
the syntax for setting physics properties. See the following examples:• Specifying the diffusion tensor.
Old syntax:
model.physics("tcdee").feature("ice1").set("D_0", newString[]{"D1", "0", "0", "0", "D1", "0", "0", "0", "D1"});model.physics("tcdee").feature("ice1").set("D_1", newString[]{"D2", "0", "0", "0", "D2", "0", "0", "0", "D2"});model.physics("tcdee").feature("ice1").set("D_2", newString[]{"D3", "0", "0", "0", "D3", "0", "0", "0", "D3"});New syntax (includes the species name in the first argument of the set method):model.physics("tcdee").feature("ice1").set("D_c1", newString[]{"D1", "0", "0", "0", "D1", "0", "0", "0", "D1"});model.physics("tcdee").feature("ice1").set("D_c2", newString[]{"D2", "0", "0", "0", "D2", "0", "0", "0", "D2"});model.physics("tcdee").feature("ice1").set("D_c3", newString[]{"D3", "0", "0", "0", "D3", "0", "0", "0", "D3"});• Accessing tensor components (in the definitions of other variables, for example).
Old syntax:
Dxx_c1, Dxy_c1, Dxz_c1...

New syntax (component index after the species name):
D_c1xx, D_c1xy, D_c1xz...

• Specifying the reaction rate vector.
Old syntax:
model.physics("tcdee").feature("reac1").set("R_0", newString[]{"R1"});model.physics("tcdee").feature("reac1").set("R_1", newString[]{"R2"});model.physics("tcdee").feature("reac1").set("R_2", newString[]{"R3"});New syntax (includes the species name in the first argument of the set method):model.physics("tcdee").feature("reac1").set("R_c1", newString[]{"R1"});model.physics("tcdee").feature("reac1").set("R_c2", newString[]{"R2"});model.physics("tcdee").feature("reac1").set("R_c3", newString[]{"R3"});

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• Accessing vector components.
Old syntax:
tfluxx_c1, tfluxy_c1, tfluxz_c1

New syntax (component index after the species name):
tflux_c1x, tflux_c1y, tflux_c1z• Specifying initial values.
Old syntax:
model.physics("tcdee").feature("init1").setIndex("c2", "c20", 0);model.physics("tcdee").feature("init1").setIndex("c3", "c30", 0);model.physics("tcdee").feature("init1").setIndex("V", "V0", 0);

New syntax:
model.physics("tcdee").feature("init1").setIndex("initc", "c20",
1);model.physics("tcdee").feature("init1").setIndex("initc", "c30",
2);model.physics("tcdee").feature("init1").setIndex("initphil","V0");• Selecting properties.
Old syntax:
model.physics("tcdee").prop("Convection").set("Convection", 1,"0");model.physics("tcdee").prop("ConvectiveTerm").setIndex("Convectiv
eTerm", "noncons", 0);

New syntax (the property name corresponds to the section in the user interface):model.physics("tcdee").prop("TransportMechanism").
set("Convection", 1, "0");model.physics("tcdee").prop("AdvancedSettings").setIndex("Convect
iveTerm", "noncons", 0);

For information about API backward compatibility for the Surface Reactions interface,see the Chemical Reaction Engineering Module release notes.
ECAD IMPORT MODULE CHANGES• The default value for the grouping property of the Import function is now set tolayer. Previously, the default was all.
• For ODB++® and ODB++(X) files (the type property is odb), new rules apply forthe initialization of the importlayer property of the Import function. Now, only

196 |CHAPTER 1: RELEASE NOTESlayers of the types Metal and Dielectric are initialized with the string on in theimportlayer string array. Previously this also included layers of type Drill.
LIVELINK™ FOR SOLID EDGE® CHANGESThe default value for the keepfree property of the LiveLinkSolidEdge function is
now set to on. Previously, the default was set to off.
LIVELINK™ FOR SOLIDWORKS® CHANGESThe default value for the keepfree property of the LiveLinkSOLIDWORKS function is
now set to on. Previously, the default was set to off.

COMSOL 5.0 API Changes
DOCUMENTATIONThe COMSOL Multiphysics Programming Reference Manual replaces the
COMSOL API for Use with Java ® Reference Manual.
DEPRECATED METHODS

The following methods were deprecated in COMSOL 5.0:
TABLE 1-3: DEPRECATED METHODS AND THEIR REPLACEMENTS
DEPRECATED METHODNEW METHOD

com.comsol.model.OptFeature.field()

OptFeature.comp()

com.comsol.model.OptFeature.field(String)

OptFeature.comp(String)com.comsol.model.Group.identifier()

Group.paramName()com.comsol.model.Material.identifier()

ModelEntity.tag()com.comsol.model.MaterialModel.
identifier()

ModelEntity.tag()com.comsol.model.ModelNode.identifier()

ModelEntity.tag()com.comsol.model.physics.Physics.
identifier()

Use tag() instead.

com.comsol.model.physics.
MultiphysicsCoupling.identifier()

ModelEntity.tag()com.comsol.model.Group.identifier(String)Group.paramName(String)com.comsol.model.Material.
identifier(String)

ModelEntity.tag(String)com.comsol.model.MaterialModel.
identifier(String)

ModelEntity.tag(String)

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TABLE 1-3: DEPRECATED METHODS AND THEIR REPLACEMENTS
DEPRECATED METHODNEW METHOD

com.comsol.model.ModelNode.
identifier(String)

ModelEntity.tag(String)com.comsol.model.physics.Physics.
identifier(String)

Use tag(string) instead.

com.comsol.model.physics.
MultiphysicsCoupling.identifier(String)

ModelEntity.tag(String)com.comsol.model.ModelEntity.name()

ModelEntity.label()com.comsol.model.ModelEntity.name(String)

ModelEntity.
label(String)com.comsol.model.ParameterEntity.
set(String, int, double)

Use the 0-based version(setIndex) instead.

com.comsol.model.ParameterEntity.
set(String, int, double)

Use the 0-based version(setIndex) instead.

com.comsol.model.ParameterEntity.
set(String, int, double[])Use the 0-based version(setIndex) instead.

com.comsol.model.ParameterEntity.
set(String, int, int)

Use the 0-based version(setIndex) instead.

com.comsol.model.ParameterEntity.
set(String, int, int[])

Use the 0-based version(setIndex) instead.

com.comsol.model.ParameterEntity.
set(String, int, int, double)

Use the 0-based version(setIndex) instead.

com.comsol.model.ParameterEntity.
set(String, int, int, int)

Use the 0-based version(setIndex) instead.

com.comsol.model.ParameterEntity.
set(String, int, int, String)

Use the 0-based version(setIndex) instead.

com.comsol.model.ParameterEntity.
set(String, int, String)

Use the 0-based version(setIndex) instead.

com.comsol.model.ParameterEntity.
set(String, int, String[]

Use the 0-based version(setIndex) instead.

This concludes the release notes for COMSOL Multiphysics version 5.5.

198 |CHAPTER 1: RELEASE NOTESI n d e x
A

AC/DC ModuleDbackward compatibility 46
new functionality 41

new functionality in 63
E

Acoustics Module

Electrochemistry Module

new functionality in 49

backward compatibility 89

Application Builder, new functionality in

new and updated models in 89

13

new functionality in 88

backward compatibility, general consid-

Electrodeposition Module

erations 33

backward compatibility 93

Battery & Fuel Cells Module

new and updated models in 92
new functionality in 91

backward compatibility 62
new and updated models 61

F

new functionality in 59
C

Fatigue Module
backward compatibility 94

CAD Import Module
new functionality in 63

ECAD Import Module
backward compatibility 87

backward compatibility 57

B

Design Module

new functionality in 94
G

CFD Module

general new functionality 13
Geomechanics Module

backward compatibility 69–70

new functionality in 95

new functionality in 67

new models in 95

new models in 68

geometry and mesh, new functionality

Chemical Reaction Engineering Modulefor 20backward compatibility 68, 72–73
new functionality in 71

H

backward compatibility 105–106, 108–

Composite Materials Module

111

new functionality in 77

new applications in 102

COMSOL API changes 192

new functionality in 97

COMSOL Compiler
new functionality in 16

L

COMSOL Multiphysics, new functionali-

new functionality in 190

COMSOL Server, new functionality in 17

LiveLink™ products for CAD

Corrosion Module
new and updated models in 85
new functionality 84

LiveLink for MATLAB
backward compatibility 191

ty in 17

backward compatibility 86

Heat Transfer Module

new functionality in 63
M

Material Library
new and updated material data in 188
new material data in 188

I N D E X | 199

new functionality in 161

MEMS Module

new models in 163

backward compatibility 121
new functionality in 115
Metal Processing Module 12
Microfluidics Module
backward compatibility 122
new models in 122
Mixer Module
new functionality in 123
Molecular Flow Module
backward compatibility 124
Multibody Dynamics Module
new functionality in 125
N

Nonlinear Structural Materials Module
new functionality in 130
new models in 132

O

operators, functions, and definitions,
new and updated 23
Optimization Module
new functionality in 133

P

Particle Tracing Module
backward compatibility 139
new functionality in 136
Plasma Module
backward compatibility 145
Porous Media Flow Module 12R

Ray Optics Module
backward compatibility 153
new applications in 150
new functionality in 148
results and visualization, new functionality in 28
RF Module
new and updated apps and models in
160

new functionality in 158
Rotordynamics Module

200 | I N D E X

SSemiconductor Module
new applications in 166
new functionality in 165
Structural Mechanics Module
backward compatibility 180
new functionality in 168
new models in 178
studies and solvers, new functionality in
25

Subsurface Flow Module
backward compatibility 182
new functionality in 181
new models in 182
W Wave Optics Module

new functionality in 184
new models in 186