Date of Award

3-11-2011

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Aeronautics and Astronautics

First Advisor

Robert Greendyke, PhD.

Abstract

In the Smoothed Accept/Reject (SAR) algorithm, the accept/reject criteria is altered from Direct Simulation Monte Carlo (DSMC): 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 ε. A relationship previously noted between Mach and ε is explored. Velocity distributions of the particles are examined for all algorithms and compared to experimental data to determine the effect of the SAR algorithm at a microscopic level. All of the comparisons to experiment show a Mach dependency that has previously been noted, and the dependency was defined for the normal shock simulations. DSMC does adequately simulate the nonequilibrium within the cells at a high Mach number through the shock, but SAR does. The SAR algorithm models the flowfield in the shock better than DSMC through a change in the collision rate and particle sampling methods, which allows for a more accurate simulation.

AFIT Designator

AFIT-GAE-ENY-11-M29

DTIC Accession Number

ADA540197

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