Radiation
The Radiation PropertyManager lets you apply surface to ambient or surface-to-surface radiation. Radiation is used for thermal studies only. For surface-to-surface radiation, you can consider radiation to the ambient (open system) or ignore it (closed system). The program calculates radiation view factors and considers blocking among the selected faces. You can define any number of features with each feature containing a number of faces with the same emissivity. For surface-to-surface radiation, all faces selected in any radiation feature radiate to each other.
Click here for a description of how the program behaves for radiation from shell surfaces.
Internally, the program divides each face to smaller areas that can radiate to each other if the face is non-planar.
To define surface to ambient radiation:
-
Do one of the following:
In the Simulation study tree, right-click Thermal Loads
and select Radiation 
.
-or-
Click Simulation, Loads/Fixture, Radiation.
-or-
Click Thermal Loads, Radiation 
(Simulation toolbar).
-
Under Type, click Surface to ambient.
-
In the graphics area, select the desired faces.
To select all faces exposed to outside at once, click Select all exposed faces. To delete a face, right-click the face and select Delete. See
Selecting All Exposed Faces
for details.
-
Under Radiation parameters, do the following:
-
Click 
.
To define surface to surface radiation:
-
Do one of the following:
In the Simulation study tree, right-click Thermal Loads
and select Radiation
.
-or-
Click Simulation, Loads/Fixture, Radiation.
-or-
Click Thermal Loads, 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.
Click here for a summary of applying thermal loads and restraints.