Radiation Conditions
Use the radiation boundary conditions to define a nonlinear radiative heat exchange condition between each model surface or surfaces and surroundings in Thermal mode. There is no radiation between model surfaces. Typically, a model not only emits radiation energy, but also absorbs energy from the surroundings at a fixed ambient temperature.
When you click > 
Radiation Condition, the Radiation Condition dialog box opens and displays the following items:
Radiation Condition, the Radiation Condition dialog box opens and displays the following items:• Name—The name of the boundary condition.
• Member of Set—The name of a boundary condition set. You can select an existing boundary condition set from the Member of Set list, or click New to open the BC Set Definition dialog box and create a new set.
• References—Select the surfaces associated with the radiation. You can select Individual, Boundary or Intent surfaces of your model. You can also select a surface set.
If you have already selected a geometric entity before opening the Radiation Condition dialog box, your selection appears in the References collector when the dialog box opens.
• Advanced—Click Advanced to display the Spatial Variation and Temperature Dependence options of Emissivity (Ɛ). Click Advanced again, to hide these options. The Advanced button is not available if you change the default values of the Spatial Variation and the Temperature Dependence options.
▪ Temperature Dependence—Specify whether the emissivity (ε) is a Function of Temperature or not. When you select Function of Temperature from the drop-down list, the 
button appears along with a list of predefined functions.
button appears along with a list of predefined functions.▪ Value—Specify a value for the emissivity (ε).
 | The value of emissivity is between 0 and 1 and is a quantity without units. |
• Ambient Temperature—Specify a value for the ambient temperature.
• Preview Ɛ—Click this button to check the spatial variation of the emissivity before you apply the radiation condition to your model. Arrows in magenta color are displayed on the selected geometrical entity.
Click OK to apply the radiation condition. A radiation condition icon is placed at all the locations where the condition is applied.
| | Radiation Conditions are not available in FEM mode. |