Particle Simulation of Hypersonic Flow
Final rept. 1 Apr 1988-31 Mar 1990
STANFORD UNIV CA DEPT OF AERONAUTICS AND ASTRONAUTICS
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A limitation of the DSMC method is that it does not allow efficient use of vector architectures that are predominate in current supercomputers. A new selection rule for collisions between simulated molecules is developed which is highly compatible with vectorization. The collision-selection rule is shown to give identical results to the DSMC method in predicting shock-wave structure and in predicting the correct mean-free path variation with density and temperature for power-law interactions ranging from hard sphere to Maxwell molecule. Algorithmic improvements beyond those related to vectorization issues alone are also introduced, making possible simulations of single-species, rarefied, 3D hypersonic flows employing 10 million particles and 0.5 million cells. The performance of the algorithm on the Cray-2 ranges from 1 to 2 microsecondsparticletime-step. Roughly 500 to 1000 time-steps are needed to time average the results of a simulation, leading to run times of 2 to 5 hours on the Cray-2 for large problems. Keywords Particle method Rarefied flow Direct simulation Monte Carlo Collision selection.
- Fluid Mechanics