The Joule Heating and Thermal Expansion Interface
The Joule Heating and Thermal Expansion interface () combines thermal, electric, and structural multiphysics effects. The predefined interaction adds the electromagnetic losses from the electric current as a heat source. In addition, the temperature from the Heat Transfer in Solids interface acts as a thermal load for the Solid Mechanics interface, causing thermal expansion. Optionally, effects from thermoelastic damping and inelastic dissipation can be used as heat sources in the heat transfer analysis.
You can use this multiphysics coupling for coupled thermal, electrical, and structural analysis of, for example, the movement of some actuator, where an electric current causes a temperature increase, which in turn leads to a displacement through thermal expansion.
When a predefined Joule Heating and Thermal Expansion interface is added from the Structural Mechanics branch () of the Model Wizard or Add Physics windows, Solid Mechanics, Electric Currents, and Heat Transfer in Solids interfaces are added to the Model Builder.
In addition, the Multiphysics node is added, containing the multiphysics coupling nodes Thermal Expansion and Electromagnetic Heating.
On the Constituent Physics Interfaces
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The Electric Currents interface is described in The Electric Currents Interface.
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The Solid Mechanics interface is described in The Solid Mechanics Interface.
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The Heat Transfer in Solids interface is described in The Heat Transfer in Solids Interface.
Settings for Physics Interfaces and Coupling Features
When physics interfaces are added using the predefined couplings, for example Joule Heating and Thermal Expansion, specific settings are included with the physics interfaces and the coupling features.
However, if physics interfaces are added one at a time, followed by the coupling features, these modified settings are not automatically included.
For example, if single Solid Mechanics, Electric Currents, and Heat Transfer in Solids interfaces are added, COMSOL Multiphysics adds an empty Multiphysics node. You can then choose from the available coupling features, Thermal Expansion, and Electromagnetic Heating, but the modified settings are not included.
Table 15-5: Modified Settings for a Joule Heating and Thermal Expansion Interface.
Physics Interface or Coupling Feature
Modified Settings
Solid Mechanics
For the Solid Mechanics interface, under Structural Transient Behavior, the Structural transient behavior is set to Quasi static.
Electric Currents
No changes.
Heat Transfer in Solids
No changes.
Thermal Expansion
The Domain Selection is the same as that of the participating physics interfaces.
The corresponding Solid Mechanics and Heat Transfer in Solids interfaces are preselected in the Thermal Expansion section.
Electromagnetic Heating
The Domain Selection is the same as that of the participating physics interfaces.
The corresponding Electric Currents and Heat Transfer in Solids interfaces are preselected in the Electromagnetic Heating section.
If you have an add-on module, such as the Heat Transfer Module or AC/DC Module, there are additional specialized physics nodes available and described in the individual module documentation.