Particle Simulations of Planetary Probe Flows Employing Automated Mesh Refinement

摘要

The data structures and algorithms of a newly developed three-dimensional direct simulation Monte Carlonprogram are outlined. The code employs an embedded three-level Cartesian mesh accompanied by a cut-cellnalgorithmto incorporate triangulated surface geometry. A simple and efficient adaptivemesh refinement algorithmnthatmaintains a local cell size and time step consistent with the local mean-free path and local mean-collision time isndetailed, along with a cut-cell algorithm that sorts triangulated surface elements into Cartesian cells and uses anMonte Carlo technique to compute the cut volume. Three-dimensional direct simulationMonte Carlo simulations ofnhypersonic flow over a 70 deg blunted cone geometry at various angles of attack are presented. For a 0 deg angle ofnattack, direct simulation Monte Carlo solutions are in excellent agreement with other simulations reported in thenliterature and with experimental results for density field and surface heat flux. New simulation results are presentednfor three-dimensional flows over the probe geometry at 10 and 30 deg angles of attack where direct simulationnMonte Carlo predictions for density field and heat flux are in close agreement with the experiment. The largestndiscrepancy is found in the heat flux along thewindward forebody (for 30 deg angles of attack),where the simulationsnoverpredict the experimental measurements by, at most, 25%.