A Comparison of Particle Simulation Implementations on Two Different Parallel Architect ures

Direct particle simur'ation is a powerful method for analyzing low density, hypersonic re-entry flows. The method involves following a large sample of representative gas molecules through motion and collision with other molecules or with surfaces in the simulated flow. In this paper, two very different parallel architectures are examined for their suitability an particle samulation computations, na;mely the Connection Machine CM-2 and the Intel iPSC/860. The difference in architectures has resulted in very diferent parallel decompositions. The two implementations are described and performance results are given. Both implementations achieve performance comparable iio a single Cray-2 CPU, however, this performance is obtained at the cost of greatly increased programming complexity.