Volumetric Boundary Conditions

Volumetric conditions in Autodesk Simulation CFD are used to generate heat. They are used in many heat transfer analyses. For 3D models, volume conditions are available when the selection type is Volume. For 2D models, Surface must be the selection type.

Use the Boundary Conditions quick edit dialog to assign all boundary conditions. There several ways to open the quick edit dialog:

  • Left click on the surface, and click the Edit icon on the context toolbar.
  • Right click on the surface, and click Edit.
  • Click Edit in the Boundary Conditions context panel.

Heat Generation

Heat Generation condition is a volumetric heat load assigned to a volume. The specified value must be divided by the volume of the part.

This is most often used to simulate the presence of heat-dissipating components in electronics assemblies.

To assign a Heat Generation condition:

  1. Select one or more volumes.
  2. Set the Type to Heat Generation, and select the Unit type.
  3. Set the Time dependence (Steady State or Transient).
  4. Set the Temperature Dependence.
  5. Specify the value in the Heat Generation field.
  6. Click Apply.
NoteFor axisymmetric models, divide by the total heat generation by the 3D volume: (pi * r² * L)

Total Heat Generation

The Total Heat Generation condition is a heat load that is not divided by part volume. This is the recommended condition for most heat-load applications as the value does not have to be adjusted if the part volume changes.

To assign a Total Heat Generation condition:

  1. Select one or more volumes.
  2. Set the Type to Total Heat Generation, and select the Unit type.
  3. Set the Time dependence (Steady State or Transient).
  4. Set the Temperature Dependence.
  5. Specify the value in the Total Heat Generation field.
  6. Click Apply.

Example assigning a Volumetric Heat Generation Boundary Condition

Note For axisymmetric models, apply the actual total heat generation. Do not apply a per-radian value. Total heat generation boundary conditions applied to Axisymmetric models in CFdesign 2010 are automatically converted to the total value from the per-radian value applied in CFdesign 2010.

Temperature Dependent Heat Generation

A temperature-dependent heat generation simulates an industrial process that operates within a narrow temperature band. Physically this is a thermostat which shuts off the heating device when a target temperature is reached. This option is available for both volumetric and total heat generation boundary conditions. The location of the sensing temperature can be either the part centroid or another location.

To assign a temperature dependent heat generation:

  1. Change the Temperature Dependent setting to Enabled.
  2. Open the Sensing Location pop-out menu.
  3. To choose the part centroid as the sensing location, simply click the Part Centroid button.
  4. To select a different location, click the Select Surface button, and click on a surface. The centroid of that surface will be the sensing location.
Note Heat Generation cannot vary with temperature and time simultaneously.