where nr is the refractive index (dimensionless),
σ is the Stefan-Boltzmann constant (SI unit: W/(m
2·K
4)), and
βR is the extinction coefficient.
This section is available when temperature-dependent material properties are used. By default the temperature of the parent interface is used and the section is not editable. To edit the Temperature field, click
Make All Model Inputs Editable (
). The available options are
User defined (default),
Common model input (the
minput.T variable, set to 293.15 K by default) and all temperature variables from the physics interfaces included in the model. To edit the
minput.T variable, click the
Go to Source button (
), and in the
Default Model Inputs node under
Global Definitions, set a value for the
Temperature in the
Expression for remaining selection section.
First, define the Refractive index nr (dimensionless) of the participating medium.The default value, 1, is usually a good approximation for the air refractive index.
Then, depending on the available quantities, the extinction coefficient βR can be specified directly or defined as the sum of the absorption and scattering coefficients. Also see
Rosseland Approximation Theory.
This section sets the absorption property of the participating medium. It is available when Absorption and scattering coefficients is selected from the
Specify media properties list. The
Absorption coefficient κ should be specified. It defines the amount of radiation,
κI(Ω), that is absorbed by the medium.
Physics Tab with Solid,
Fluid,
Porous Medium,
Biological Tissue, or
Building Material selected in the model tree: