High Vectorization Ratio Coding of DSMC Method Analysis

Abstract

Conventional DSMC method analysis requires huge execution time in spite of its simple calculation method and use of high performance computer. This is because its analysis code has low vectorization ratio. In order to improve the vectorization ratio, in this study, the following ideas were introduced to the code : (1) random access array for particle registration to cell, (2) virtual boundary cell, (3) modification of flow-into and flow-out particle management and (4) lumpgeneration and storage of random numbers. Requiring large memory capacity, these ideas can avoid the execution of recursive procedures and improve the calculation efficiency. As a results, it was confirmed that the vectorization ratio was significantly improved (approximately from 18% to 94%) and the execution time was drastically reduced (acceleration ratio : approximately 11.3). It seems that this code contributes the computing load reduction of rarefied gas flow analysis.