A HIGH-EFFICIENCY PARALLEL SOLUTION OF THE RADIATIVE TRANSFER EQUATION

Abstract

Solution of the radiative transfer equation for nontrivial geometry and optical properties is a massive numerical problem, and can benefit from parallel processing to reduce the time to solution. Spatial parallelization is presented, applied to the DOTS algorithm with finite-volume directional discretization, and an explicit pseudo-time-stepping iterative solution with multigrid acceleration. Two- and three-dimensional benchmark problems were investigated with up to 16 processors on a shared-memory vector machine. In contrast to previous studies, high parallel efficiency was demonstrated up to the highest number of processors. The reasons for the good performance can be traced to the explicit iterative algorithm, which permits easy parallelization without affecting the rate of convergence; and to the use of high-bandwidth shared memory, which significantly reduces communication overhead.