ABSTRACT
The fundamental principle governing the temperature field within an absorbing, emitting, and scattering medium is the same as that for a nonparticipating medium; that is, the expression of conservation of energy within the medium. The presence of a radiation field within the fluid will alter the classical conservation equations of momentum and energy as the result of three effects. These are: the radiation energy flux constitutes an additional mechanism for heat transfer to or from a fluid element; a fluid element will contain radiant energy as well as molecular energy; and the radiation pressure tensor will augment the conventional fluid dynamic pressure tensor. One of the most important dimensionless parameters associated with radiation-participating media is the optical thickness of the medium. An additional radiation regime is that of radiation slip, which differs in a specific manner from the previous cases of the optically thin and optically thick limits.
