Boundary Conditions
The boundary condition parameters for the
Radiation module apply to boundaries in the Flow Analysis Tree.
The boundary conditions appear in the Properties panel when you select a boundary in the Flow Analysis Tree under General Boundaries.
Radiation
• Emissivity—Emissivity set to zero is equivalent to a totally reflective boundary, in which no energy is absorbed due to the incident radiation. Emissivity set to 1 is equivalent to a fully absorbing boundary.
• Source Transparent—Set to No by default, which implies that external sources do not act through the boundary.
Open
With the Open boundary condition, radiative fluxes to pass freely. This boundary acts as a transparent boundary in communication with the external temperature that you set and can differ from the global environment temperature.
• Source Transparent—If set to Yes, radiative flux from external sources can enter the domain.
Transparent
In the Transparent boundary condition, radiative flux can enter the domain through the boundary.
Environment
Environment boundary condition excludes the selected boundary from the view factor calculations. It acts as an open boundary that communicates with the environment at the global environment temperature. You can model this boundary condition as an open boundary condition with the external temperature input set to the same value as the global environment temperature.
Interface Condition
If you set both volumes on the sides of an interface to Opaque or Transparent, then the interface is set as a default interface which does not influence the radiative heat transfer. If you set the volume on one side of the interface to Opaque and set the other side to Transparent, then interface attributes are the same as those for a radiation boundary condition.
Output
• Default
• User Select
◦ Area
◦ Normal
For wall boundaries, Radiation Flux (W/m2) is available as an output option in the GUI viewing window.