Heat Generation

What Does Heat Generation Do?

• Internal heat generation is applied to a part that will either act as a heat source or heat sink throughout the analysis. The heat generation is specified in one of two ways:
  • Heat per unit volume, such as W/(in³).
  • Total Heat, such as W or Btu/(s·in³). Specify the total heat when the Enter Heat Generation as Total Heat checkbox is activated.
• The magnitude of the internal heat generation can vary with the temperature of the elements.
• For the internal heat generation to be applied in the analysis, assign a Heat generation multiplier in the Multipliers tab of the Analysis Parameters dialog box. This value is multiplied by the internal heat generation specified, and the product is used for the internal heat generation load in the analysis.

Caution: Heat generation loads cannot be defined using the Total Heat option if you plan on exporting the model to the Autodesk Nastran Editor or running the solution using the Nastran solver. Specify heat generation on a per-unit-volume basis for Nastran solving and exporting cases.

Apply Heat Generation

1. Select one or more parts.
2. Click Setup Thermal Loads Internal Heat Generation. Alternatively, right-click in the display area and click Add Heat Generation from the context menu.
3. If you wish to specify the total heat generation per selected part, activate the Enter Heat Generation as Total Heat checkbox. Leave this box unchecked if you wish to enter the heat generation per unit volume of the parts.
4. Specify the magnitude of the internal heat generation in the Internal Heat Generation field. Enter total heat or per-unit-volume heat, depending upon your action for step 2. A positive value represents a heat source. A negative value represents a heat sink.
5. If the heat generation will vary according to the temperature of the element, activate the Temperature Dependent check box and specify the curve number that will control the heat generation. Then,
   1. Press the View / Edit Curve button.
   2. In a tabular format, specify the heat generation magnitude to use at each temperature value. This curve must include the entire temperature range that the elements experience throughout the analysis. Linear interpolation is used to define the heat generations at temperatures between the data points. During the calculations, temperature values at the element integration points are used to determine the heat generation in the element.
   Tip: When using temperature-dependent heat generation, the calculated heat generated can be viewed in the summary file. See the Perform Thermal Analyses page for details.
6. For transient heat transfer analyses, specify the Load Curve that will control heat generation over time. A load curve of 0 indicates that heat generation will be constant with respect to time.
   1. Press the Curve button to define a load curve within the Load Curve Editor. Alternatively, click Setup Model Setup Parameters Analysis Parameters at a later time to define the load curve within the Analysis Parameters dialog box.