Article
Gridless DSMC
Mathematics Department, Michigan State University, D304 Wells Hall, East Lansing, MI 488241027, United States
Journal of Computational Physics (Impact Factor: 2.43). 09/2008; 227(17):80358064. DOI: 10.1016/j.jcp.2008.04.038 ABSTRACT
This work concerns the development of a gridless method for modeling the interparticle collisions of a gas. Conventional fixedgrid algorithms are susceptible to gridmismatch to the physical system, resulting in erroneous solutions. On the contrary, a gridless algorithm can be used to simulate various physical systems without the need to perform gridmesh optimization. An octree algorithm provides the gridless character to a direct simulation Monte Carlo (DSMC) code by automatically sorting nearestneighbor gas particles into local clusters. Automatic clustering allows abstraction of the DSMC algorithm from the physical system of the problem in question. This abstraction provides flexibility for domains with complex geometries as well as a decreased code development time for a given physical problem. To evaluate the practicality of this code, the time required to perform the gridless overhead from the octree sort is investigated. This investigation shows that the gridless method can indeed be practical and compete with other DSMC codes. To validate gridless DSMC, results of several benchmark simulations are compared to results from a fixedgrid code. The benchmark simulations include several Couette flows of differing Knudsen number, lowvelocity flow past a thin plate, and two hypersonic flows past embedded objects at a Mach number of 10. The results of this comparison to traditional DSMC are favorable. This work is intended to become part of a larger gridless simulation tool for collisional plasmas. Corresponding work includes a gridless field solver using an octree for the evaluation of long range electrostatic forces. We plan to merge the two methods creating a gridless framework for simulating collisionalplasmas.
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