Anti-diffusive-like-behavior in semi-analytic radiative shocks via multigroup Sn transport with constant cross sections

Semi-analytic lab-frame radiative shock solutions have been presented recently, wherein the radiation is modeled with either grey (frequency independent) nonequilibrium-diffusion or grey Sn-transport. As a first step toward incorporating frequency dependence, we retain grey cross-sections such that the frequency dependence of the problem is strictly due to the Planck function. By using multigroup frequency integration the frequency-dependent radiation-transport equation may be solved, and group-dependent radiation temperatures may be defined for each group. Our main result is: When a Zel'dovich temperature spike exists in a radiative shock solution, there exists a transition group gTgT, such that for all frequency groups below gT the group-dependent radiation temperatures are spatially monotonic, and for all frequency groups above gT the group-dependent radiation temperatures are spatially non-monotonic. We present numerical evidence of our claim and make no claim as to the monotonicity of group gT.