Improved Collision Modeling for Direct Simulation Monte Carlo

Abstract

The key to Direct Simulation Monte Carlo (DSMC) is decoupling of particle motion and particle collisions. Particles within each cell are randomly chosen as collision partners, and the collision is then accepted or rejected by comparing collision criteria to a random number. In the Smoothed Accept/Reject (SAR) algorithm, the accept/reject criteria is altered: rather than a binary function of rejection or acceptance, collisions can be partially accepted with a linear weighting between zero and one. The partial acceptance is based on a band around the original accept/reject criteria defined as a percentage of the collision criteria, which is called. The weighting is used in sampling the particles in order to calculate the macroscopic flowfield parameters. Previous work included comparisons to experimental data using inverse shock thickness, the results of which implied a relationship for the appropriate value First and foremost I would like to thank my family and friends that have supported me along my journey throughout my life. My parents have always loved me and supported me, and hopefully I can make them proud. My brother, who definitely got the smart genes as well as the tall genes, has been a constant source of computer advice and encouragement. My grandparents, who are no longer with us, always provided us with a place we could call home no matter where we were living at the time and helped me grow to be the person I am. The amount of love and pride they had for their children and grandchildren is immeasurable and will never be forgotten. To my friends here at AFIT, we've spent many a long night in the Linux lab, and you guys helped me make it through! Dave Doak has been a lifesaver in the Linux lab, and helped us in anyway he could. Without his assistance in the Linux lab none of us would have accomplished as much as we have. My advisor, Dr Greendyke provided wisdom and insight, and I learned a great deal working with him over the past year and a half.