To define a surface radiative interaction:

From the main menu bar, select InteractionCreate.

Tip:  You can also create a surface radiative interaction using the tool in the Interaction module toolbox.

In the Create Interaction dialog box that appears, do the following:

Name the interaction. For more information about naming objects, see “Using basic dialog box components,” Section 3.2.1.

Select the step. You can define radiation from a surface only during a heat transfer, coupled temperature-displacement, or coupled thermal-electrical step.

Select the Surface radiation to ambient type of interaction.

Click Continue to close the Create Interaction dialog box.

Use one of the following methods to select the surface:

Use an existing surface to define the region. On the right side of the prompt area, click Surfaces. Select an existing surface from the Region Selection dialog box that appears, and click Continue.

Note:  The default selection method is based on the selection method you most recently employed. To revert to the other method, click Select in Viewport or Surfaces on the right side of the prompt area.

Use the mouse to select a region in the viewport. (For more information, see “Selecting objects within the current viewport,” Section 6.2.)

If the model contains a combination of orphan mesh instances and native geometric part instances, click one of the following from the prompt area:

• Click Geometry if you want to select the surface or vertex from native geometry.

• Click Mesh if you want to select the surface or node from an orphan mesh.

You can use the angle method to select a group of faces or edges from native geometry or a group of element faces from an orphan mesh. For more information, see “Using the angle method to select multiple objects,” Section 6.2.3.

In the Edit Interaction dialog box that appears, perform the following steps:

In the Emissivity field, enter the emissivity of the surface, .

In the Ambient temperature field, enter the ambient temperature, .

If you want to vary the ambient temperature with time, click the arrow to the right of the Ambient temperature amplitude field and select the amplitude of your choice from the list that appears. If desired, click Create to create a new amplitude; see “Creating an amplitude,” Section 38.3, for more information.

Specify the absolute zero temperature, , on the temperature scale being used and the Stefan-Boltzmann constant, , in the Edit Model Attributes dialog box, as described in “Editing model attributes,” Section 9.8.4.

Click OK to create the interaction and to close the editor.