To define surface to surface radiation:
- Do one of the following:
- In the Simulation study tree, right-click Thermal Loads
and select Radiation 
.
- Click .
- Click Radiation (Simulation toolbar).
The Radiation PropertyManager appears.
- Under Type, click Surface to surface.
- In the graphics area, select one or more faces. Note that a non-planar face can radiate to itself.
-
To consider radiation to ambient in addition to surface to surface radiation, click Open system, select a unit system, and type the Ambient Temperature
. To associate a time curve with the ambient temperature, click Use Time Curve 
then click Edit, and import or define a time curve. The value of the ambient temperature at any time instant is calculated by multiplying the specified ambient temperature value by the corresponding Y value of the time curve. This option is available for transient thermal studies only.
-
Set the Emissivity . To associate a temperature curve with the emissivity, click Use Temperature Curve
then click Edit, and import or define a temperature curve. The value of the emissivity at a given temperature is calculated by multiplying the specified emissivity value by the corresponding Y value of the temperature curve.
- Click
.
- To include other faces with different emissivity values, define any number of radiation features through different definitions. All faces will participate in the radiation. The program calculates view factors and blocking automatically.
For surface to surface radiation, the program calculates radiation view factors during analysis, a process that takes more time than usual for a similar problem without surface-to-surface radiation.