Efficient smoothed particle radiation hydrodynamics I: Thermal radiative transfer

This work presents efficient solution techniques for radiative transfer in the smoothed particle hydrodynamics discretization. Two choices that impact efficiency are how material and radiation energy coupled, which determines number of iterations needed to converge emission source, diffusion equation is solved, must be done each iteration. The coupled equations solved using an inexact Newton iteration scheme based on nonlinear elimination, reduces within time step. During iteration, Krylov iterative methods with a multigrid preconditioner, abstracts optimizes much communication when running parallel. code verified infinite medium problem, one-dimensional Marshak wave, two three-dimensional manufactured exhibits first-order convergence second-order space. For these problems, independent spatial points processors.