Automatic and manual thermal couplings (ANSYS)

In the ANSYS environment, you can use the Automatic Thermal Coupling and Manual Thermal Coupling commands to create coupled degrees-of-freedom between selected nodes.

• Use Automatic Thermal Coupling to automatically create thermally coupled degrees-of-freedom between offset or symmetric meshes.

• Use Manual Thermal Coupling to manually create either thermally coupled degrees-of-freedom or to create constraint equations between the temperature degrees-of-freedom.Select the Coupled DOF option from the Type list to create coupled degrees-of-freedom between selected nodes.Select the CE option from the Type list to define a constraint equation that relates the degrees-of-freedom on the selected nodes.

Specifying the degrees of freedom to couple

In the Automatic Thermal Coupling dialog box and the Manual Thermal Coupling dialog box when you select the Coupled DOFoption, you use the DOF option to control the degrees of freedom that the software couples.

• Select TEMP to create a coupling for the nodes’ thermal degrees-of-freedom. TEMP is the only valid option if the nodes that you are coupling are attached to 3D elements.If the nodes you are coupling are attached to 2D elements, the software uses the temperature at the midsurface of the elements to create the coupling.This option corresponds to the ANSYS CP, LAB=TEMP command.

• Select ALL to create a coupling for the nodes’ thermal and structural degrees-of-freedom. This option corresponds to the ANSYS CP, LAB=ALL command.

For more information on defining sets of nodal degrees of freedom in ANSYS, see CP in the ANSYS Commands Reference.

Understanding the automatic thermal coupling process

With Automatic Thermal Coupling, the software pairs the nodes on the independent side of the model with nodes on the dependent side of the model using a coordinate system and nodal search tolerance you specify. The software searches for nodes based on the translation from a designated independent node to a designated dependent node using the search tolerance. You specify the directions and rotations in which the software couples the nodes.

For more information, see Automatic coupling.

Setting an appropriate Node Match Tolerance for automatic thermal coupling

If the value for the Node Match Tolerance is set too high, the software may find multiple matching nodes. In this case, the software's node matching algorithm attempts to choose the closest node on a free face. However, there are cases in which the software may not be able to determine the appropriate match for a node. To help avoid this issue, in general, you should keep the specified Node Match Tolerance to less than 50% of the defined element size.

Specifying the reference coordinate system in automatic thermal coupling

By default, when you create an Automatic Thermal Coupling, the software uses the reference coordinate system to determine the corresponding pair of nodes to be coupled within the selected object. For a model with rotational or cyclic symmetry, the reference coordinate system must be cylindrical.

Where do I find it?

Automatic Thermal Coupling and Manual Thermal Coupling

Application	Pre/Post
Prerequisite	An active Simulation file with ANSYS as the specified solverThermal or Axisymmetric Thermal as the specified analysis typeSteady State Thermal as the specified analysis type
Command Finder	Automatic Thermal Coupling or Manual Thermal Coupling
Menu	Insert→Load→Automatic Thermal Coupling or Manual Thermal Coupling

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Automatic and manual thermal couplings (ANSYS), Simcenter 3D 2021.1 Series

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