Use this node to set an absorbing medium’s boundary opaque to radiation. This condition applies for all the radiative beams defined by an active
Incident Intensity condition. If the beam propagates from the opaque surface to the absorbing medium, the radiative intensity is set to 0. Otherwise, the radiative beam is absorbed by the surface and deposits all its energy on it. A boundary heat source,
Qb, is defined and corresponds to the energy deposited by all the radiative beam on the opaque surface. See
Absorbing Medium (Radiative Beam in Absorbing Medium Interface) for the modeling of radiative beam absorption in the medium.