Heat Source

What Does a Heat Source Load Do?

• Heat Source loads can either supply heat to the model or take away heat from the model during the analysis. The direction of the heat flow is controlled by the sign on the value in the Magnitude field. A positive value causes heat to be supplied to the model (heat source). A negative value causes heat to be taken away from the model (heat sink).
• You can apply a Heat Source load to vertices (nodal load) or surfaces.

Apply a Surface Heat Source

1. Optionally, select the surface or surfaces to receive the load. Then, either:
   • Click Setup Thermal Loads Heat Source, or
   • Right-click in the display area and choose Add Surface Heat Source from the context menu.
   Note: You do not have to preselect surfaces before accessing the ribbon command. You can also select surfaces after clicking the Heat Source ribbon command. However, you must preselect surfaces before you can access the Add Surface Heat Source command from within the context menu.
2. If you did not preselect the surfaces to receive the Heat Source load, select them now.
3. Optionally, if you want to define the total heat flux magnitude per selected surface, rather than the heat per unit area, activate the Enter Magnitude as Total Heat checkbox.
   Note: This option is only available for CAD-based models with unmodified meshes generated using the Solid or Plate/Shell options. CAD model surface area data is required when specifying the total heat flux magnitude. When any of the following three conditions apply, you must define the heat per unit area:
   • The model is hand-built (structured mesh geometry).
   • The model is CAD-based, but the mesh has been manually altered. Changing the attributes of surface mesh lines, moving nodes, or adding or deleting lines renders the surface area data of the CAD model unreliable.
   • The load is applied to a midplane-meshed surface or the outer surface of a part that is later converted to a midplane mesh. The midplane surface area cannot be directly determined from the CAD model data.

   If you define the load using the Enter Magnitude as Total Heat option, the specified magnitude is applied to each selected surface. For example, if you select three surfaces, check this option, and specify a magnitude of -10 W, then a total heat sink of 30 W is applied (-10 W per surface). Conversely, if you do not activate the Enter Magnitude as Total Heat option, then it does not matter how many surfaces are selected. The magnitude is applied uniformly on a per-unit-area basis to however many surfaces are selected. The greater the total selected surface area, the greater the total load.

4. Continue by following the procedure in the Complete the Definition of a Heat Source Load section of this page.

Apply a Nodal Heat Source

1. Optionally, select the vertex or vertices to receive the load. Then, either:
   • Click Setup Thermal Loads Heat Source, or
   • Right-click in the display area and choose Add Nodal Heat Source from the context menu.
   Note: You do not have to preselect vertices before accessing the ribbon command. You can also select vertices after clicking the Heat Source ribbon command. However, you must preselect vertices before you can access the Add Nodal Heat Source command from within the context menu.
2. If you did not preselect the vertices to receive the Heat Source load, select them now.
3. Continue by following the procedure in the Complete the Definition of a Heat Source Load section of this page.

Tip: See the comments under the Application of Loads and Constraints at Duplicate Vertices heading on the Loads and Constraints page for information about how nodal loads are applied at duplicate vertices.

Complete the Definition of a Heat Source Load

After following the preceding steps for adding nodal or surface heat source loads, complete the load setup as follows:

1. If you are applying the heat source to plate elements, and you want it to be applied to both sides, activate the Apply load to both sides check box. Since there is only one vertex through the thickness of a plate element, applying a load on both sides is equivalent to applying twice the load on one side.
2. If you are performing a transient heat transfer analysis, select the load curve that will be applied to the heat source in the Load Curve drop-down box. A Load Curve of 0 indicates that the value will be kept constant throughout the analysis. Next, if you are controlling the load with a curve:
   • Press the Curve button to define a load curve in the Load Curve Editor, or
   • Define the load curve within the Analysis Parameters dialog box at a later time (Setup Model Setup Parameters Analysis Parameters).
   Note: The heat source is scaled by theConvection multiplier on the Multipliers tab of the Analysis Parameters dialog box. In addition to scaling the heat source, you can use the multiplier to change the sign of the load. That is, you can use the multiplier to alternate between a heat source (positive product) and a heat sink (negative product).