ABSTRACT
It is clear from the relations given in Chapters 10 and 11 that simple solutions for temperatures and energy ows are usually not possible for the combined equations of radiative transfer and energy conservation in translucent media. For some conditions, however, simplications can be made that provide useful results. If a translucent medium is weakly attenuating, or the medium boundaries are kept cold, or if there is a cold medium exposed to a strong radiation source, then certain terms can be neglected in the transfer equations, resulting in simplied relations. When the medium is optically dense, the diffusion approximation can be used; in this case radiative transfer is similar to heat conduction with a temperature-dependent thermal conductivity and can be readily combined with heat conduction. For these special cases there may be convenient solution methods available. These formulations are also useful for comparisons of limiting cases with more general solutions obtained by complex methods.
