System Coupling Analyses Using Maxwell

Ansys System Coupling™ facilitates and manages the execution of coupled simulations between multiple physics solvers, coupling active cosimulation participants using either System Coupling's graphical user interface (GUI) or its command-line interface (CLI).

The Maxwell application can engage as a coupling participant in thermal cosimulations with Ansys Fluent^® and Ansys Mechanical™ applications and in electrical arc modeling simulation with Ansys Fluent, Ansys Motion™, and Ansys Twin Builder^® applications. System Coupling provides enhanced control over coupled simulation processes, including automatic starts and restarts for participants, the ability to manipulate the System Coupling data model, an interactive solution workflow, and multiple output formats for reviewing and postprocessing results.

In System Coupling analyses, each participant completes its physics and coupling setups in its own user interface generating a Participant Setup (.scp) file along with its solver file(s). The coupled analysis itself includes loading participants, setting values for coupling-related settings, specifying coupled analysis settings, and starting the run. Once the solution has started, System Coupling directs the execution of the coupled analysis – including general coupling management, participant communications, and transfers of data between participants.

Note: For detailed information on System Coupling in general, refer to the System Coupling User’s Guide. For details on working in System Coupling's GUI or CLI, refer to the Using System Coupling's User Interfaces section.

Note: For examples of Maxwell participating in cosimulations, review the coil-and-core induction heating, bar-and-coil induction heating, bus bar, and electric motor examples in System Coupling Tutorials. Also see Electrical Arc Modeling Using System Coupling.

Supported Capabilities and Limitations

The following capabilities are supported for System Coupling analyses with Maxwell:

Multi-region data transfers for Maxwell participants.
Maxwell 3D AC Magnetic, Maxwell 3D Transient, and Maxwell 2D Transient Cartesian, XY geometry mode solutions.
Update frequency controls for a Maxwell participant running a steady solution.
Automatic and manual distribution parameters for parallel execution
Dynamic remeshing and remapping during the execution of Maxwell 3D AC Magnetic simulations with time-dependent motion or excitation defined. For details, see Mapping Process in the System Coupling User's Guide.
Variable displacement for simulations with time-dependent motion defined.
Thermal data transfers on bodies. EM loss can be provided to other coupling participants, and temperature can be received from them.
Motion data transfers on coupled bodies.
Parallel/distributed processing.
Electrical arc modeling:
- System Coupling between the Maxwell, Fluent, and Twin Builder applications can be used to model an electric arc in a static design.
- System Coupling between the Maxwell, Fluent, and Motion applications can be used to model an electric arc in a device with motion.

The following are known limitations when using System Coupling with Maxwell:

Only Maxwell 3D AC Magnetic, Maxwell 3D Transient, and Maxwell 2D Transient, Cartesian, XY geometry mode solution types are supported.
For electrical arc modeling, only Maxwell 3D magnetostatic designs are supported.
Maxwell 3D AC Magnetic solution type is limited to a single frequency.
Variable velocity is not supported for designs with time-dependent motion and/or excitations.
Update frequency controls are not supported when Maxwell runs a solution with time dependencies.

Using HPC Distribution Settings for Coupled Analyses

System Coupling supports the use of Maxwell's automatic and manual HPC distribution parameters for distributed coupled analyses. Each of these Execution Control settings corresponds to one of Maxwell's distributed analysis parameters.

Auto Distribution Settings: Whether job distribution is performed automatically.

When auto-distribution is disabled, the following manual settings are available:

Include HPC Distribution Types: List of the HPC distribution types to be included for distributed runs.
Number of Cores Per Task: Number of HPC cores to be used per task.
Batch Options: Batch option arguments to be applied to the run.

For more information, see Using AEDT HPC Distribution Options in the System Coupling User's Guide.

Variables Available for System Coupling

The following variables will be available on convective boundaries:

Name / Internal Name	Transfer Direction	Data Type	Physical Type
Loss / Loss	Output	Scalar	Heat Rate
Temperature / Temperature	Input	Scalar	Temperature

The following variables will be available for magnetostatic simulations:

Name / Internal Name	Transfer Direction	Data Type	Physical Type
Arc Voltage	Output	Scalar	Voltage
Arc Current	Input	Scalar	Current
Loss / Loss	Output	Scalar	Heat Rate
Lorentz Force	Output	Vector	Force
Electrical Conductivity	Input	Scalar	Electrical conductivity
Temperature	Input	Scalar	Temperature

System Coupling Related Settings

System Settings

To enable coupling with Maxwell, the environment variable ANSYSEM_ROOT252 must be set to the location of your Ansys Electromagnetics installation.

Note: The environment variable name is ANSYSEM_ROOT<major><minor>, where <major> is the two digit major version number (the last two digits of the year); and <minor> is the one digit minor version number. For example, for the Ansys Electronics 2025 R1 release, the environment variable name is ANSYSEM_ROOT252. For the Student Version of the software, the variable name is ANSYSEM_ROOTSV<major><minor>.

For Windows, this environment variable is automatically set during the installation of the Ansys Electromagnetics Suite (for example, C:\Program Files\ANSYS Inc\v252\AnsysEM).
For Linux, you must set this environment variable manually (for example, /opt/ansys_inc/v252/AnsysEM).

Note: The environment variable must be set on all hosts if the analysis is distributed to multiple hosts. For Windows, this environment variable must generally be set as a System environment variable (not a user environment variable) for distributed analysis so that it is set for the Ansoft RSM Service. For Linux, the user must ensure that the environment variable is set for the AnsoftRSM Service daemon processes.

You must also integrate Maxwell with Ansys: from the Start menu, select Ansys EM Suite 2025 R2 > Modify Integration with Ansys 2025 R2.

Maxwell Settings

Solution Type:

Must be set to one of the following:

AC Magnetic for Maxwell 3D designs only.
Transient for either Maxwell 3D or Maxwell 2D designs. For Maxwell 2D designs, you must also specify the Cartesian, XY geometry mode when selecting this solution type.
Magnetostatic for Maxwell 3D designs only.

Materials:

Bodies to receive temperature data must have temperature-dependent properties. Note that when the same materials are used in multiple participants, common properties (e.g., conductivity) must be consistently defined.

Motion:

Motion must be appropriately and consistently defined for all bodies involved in the analysis.

Stationary bodies must not move from the reference position or participate in multiple reference frames during the cosimulation.

Motion should be defined with a (rigid body) displacement.

For more information, see Additional Participant Setup Considerations in the System Coupling User’s Guide.

Creating a System Coupling Setup

The System Coupling Setup enables the exchange of data between participants by creating an interface between regions on the participant models.

To create a coupling setup, select ( Optimetrics > Add > System Coupling Setup), and do one of the following:

For AC Magnetic designs, select the desired solution Setup, Frequency, and input/output quantities. For the Temperature quantity, click the Object temperature button to open the Temperature of Objects dialog in which you can choose to Include Temperature Dependence, and to set the temperatures for model objects composed of materials having temperature-dependent properties.
For AC Magnetic designs with time-dependent motion, create a dataset to define the position of the moving body, and design variables for the coupling time as provided by System Coupling and the displacement vector of the body.
For 3D Magnetostatic designs:
- For Maxwell\Twin Builder coupling, input a current excitation; the voltage value output to Twin Builder will be calculated from loss/current.
- For Maxwell\Fluent system coupling, input temperature, system coupling time, and electrical conductivity.
- For an example of system coupling involving the Maxwell, Twin Builder, and Fluent applications, see Modeling an Electric Arc in a Run Rails Design.
- For an example of system coupling involving the Maxwell, Motion, and Fluent applications, see Modeling an Electric Arc in a Device with Motion.
For Transient designs, select the desired solution Setup, Start time, End time, and input/output quantities. For the Temperature quantity, click the Object temperature button to open the Temperature of Objects dialog in which you can choose to Include Temperature Dependence, and to set the temperatures for model objects composed of materials having temperature-dependent properties.
For Transient designs with time-dependent motion/excitation:
- Define motion on coupled bodies.
  Note: A profile or expression can be used to define rigid body motion using total displacement relative to the original object location.
- Create design variables for both the coupling time (as provided by System Coupling) and the displacement vector of the body.
- For Transient designs, Ansys Electromagnetics time is associated with System Coupling time. Maxwell uses this time to calculate excitation and position, but itself always begins its calculations at time zero.
- Optionally, the following inputs can also be defined as a function of System Coupling time: Maxwell Timestep Size, Loss Averaging Start Time, Loss Averaging Stop Time/Duration.

Generating a System Coupling Participant Setup File

System Coupling uses each participant's Participant Setup (.scp) file and the corresponding Python (.py) configuration file to load the participant and its information into the data model.

To use System Coupling, you must generate a System Coupling participant file (.scp). Once the Maxwell setup is complete, generate the file using either of the following options:

In the System Coupling Setup window, the system coupling configuration files are generated when you click the OK button.
In the Project Manager under Optimetrics, right-click your System Coupling Setup and select Generate Configuration Files.

In both cases, the configuration files needed by System Coupling (an .scp file and a .py file) are generated at the same time and in the same location as the Maxwell project file.

Licensing Considerations when using System Coupling

A distinct license is required for each coupling participant product, but no additional licenses are required for the System Coupling infrastructure itself.

Note, however, that Ansys EnSight is required for the postprocessing of System Coupling’s interface results. If you are using a Multiphysics Licensing Bundle that does not include an EnSight license (e.g., the Ansys Mechanical Maxwell bundle), you will need a separate EnSight license to visualize cosimulation results.

For more information on applicable licenses, see Product Licensing Considerations in the System Coupling User's Guide.