Stability of explicit radiation-material coupling in radiative transfer calculations

We show that explicit radiation-material coupling, which is essentially always stable for infrared radiative transfer is conditionally stable in the high energy density regime. A linearized stability analysis is first performed for a simple infinite-medium problem that yields both a criterion for unconditional stability, a time-step restriction that applies for conditional stability, and a time-step criterion that always applies for non-oscillatory solutions. This analysis is then extended to include space dependence with the result that the system is always conditionally stable, but with a time step restriction somewhat different from the infinite-medium case. Nonetheless, the time step restriction for non-oscillatory solutions remains the same. Computations are presented that confirm the predictions of our analysis, and conclusions are given.

► Explicit material radiation coupling is conditionally stable. ► Analysis provides criteria for stability and non-oscillatory solutions. ► Numerical results confirm analysis. ► Numerical results also demonstrate preservation of maximum principle for implicit coupling.