This node defines a boundary opaque to radiation. It prescribes incident intensities on a boundary and accounts for the net radiative heat flux,
qr,net, that is absorbed by the surface.
If this node is selected from the Pairs menu, choose the pair on which to apply this condition. A pair has to be created first. See
Identity and Contact Pairs in the
COMSOL Multiphysics Reference Manual for more details.
There is one standard model input — the Temperature T, which is used in the blackbody radiative intensity expression.
Select a Wall type to define the behavior of the wall:
Gray wall or
Black wall. The definition of the incident intensities used to define the incoming and outcoming radiative heat fluxes depends on the option selected in this list.
If Gray wall is selected the default
Surface emissivity ε value is taken
From material (a material defined on the boundaries). For
User defined enter another value or expression.
An emissivity of 0 means that the surface emits no radiation at all and that all outgoing radiation is diffusely reflected by this boundary. An emissivity of
1 means that the surface is a perfect blackbody: outgoing radiation is fully absorbed on this boundary. When the node is added in the Radiation in Participating Media interface, the radiative intensity along incoming discrete directions on this boundary is defined by
If Black wall is selected, no user input is required, and the radiative intensity along the incoming discrete directions on this boundary is defined by
