Effectiveness of Pentran (TM)'s unique numerics for simulation of the Kobayashi benchmarks

In this paper, we use the PENTRAN (Parallel Environment Neutral-particle TR ANsport), 3-D parallel Sn code to solve three 3-D benchmark problems. Each of the problems contains three regions: source, void, and shield. Two shiel d materials, zero (pure absorber) and 50% scattering ratios, are tested. Th is combination of a discontinuous source, void, and low scattering shield i s highly problematic for the Sri method that uses a limited number of direc tions. In this paper, we demonstrate that the unique numerical formulations and features of PENTRAN provide the capability of obtaining relatively acc urate solutions for such situations. For the pure absorber cases, we obtain maximum differences from the analytical solutions of < 40%, 24%, and 20% f or the problems I to 3, respectively. For the 50% scattering cases, these d ifferences reduce to < 20% for all problems. In most cases, the maximum err or occurs at large distances from the source. We have demonstrated that in order to obtain these solutions, it is necessary to use three important fea tures of PENTRAN, including variable meshing, Taylor Projection Mesh Coupli ng (TPMC), and the adaptive differencing strategy with the DTW and EDW diff erencing schemes. (C) 2001 Published by Elsevier Science Ltd.