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Advanced Techniques for High-Performance Computer Simulations of Rarefied Neutral Gas and Plasma Flo
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| As computers increase in speed and memory, particle kinetic simulations will continue to expand in their capability to address physical problems in which non-equilibrium microphysical processes are of central importance and for which fluid-based approaches are inadequate. With previous support from the Applied Information Systems Research Program we have successfully developed a highly parallelized kinetic model based on Direct Simulation Monte Carlo (DSMC) for application to a variety of space science rarefied gas applications. The features and capabilities of the model are as follows: ï Collisional kinetic neutral and ionized gas physics with rotational/vibrational degrees of freedom and photodissociation on 1D, 2D, 3D unstructured meshes, ï An integrated Euler hydrodynamics solver incorporating a fully functional hybrid scheme with adaptive boundary feedback between kinetic and fluid domains, and ï Dust particles for modeling dusty-gas flows such as dusty gas cometary atmospheres and volcanic plumes on outer planet satellites. A five-year research program is proposed in which an important set of developments will be studied and implemented using our kinetic ion/neutral particle simulation model for space science as a test bed. Just as our past and proposed advances are built on the published work of others, the dissemination of innovative techniques to be developed are intended to contribute to the general advancement of particle kinetic simulation work. Our specific goals are as follows: ï Extension of our already-developed finite-element based Poisson solver for self-consistent electric fields to self-consistent solution of electric and magnetic fields in plasma particle simulations. A finite element approach has the potential to permit using unstructured meshes in fully electromagnetic particle plasma simulations. ï A new computational mesh method based on mixed unstructured (tetrahedrons) and structured (hexahedrons) cells. This could lead to a computational speed-up of up to a factor 6. ï A novel noise reduction/optimization scheme--for the first time in DSMC--which is similar to the complex particle kinetic (''blob'') methods now in forefront plasma kinetic particle-in-cell (PIC) research. This could lead to a dramatic decrease in the number of simulation particles required for many applications. ï New physics attributes for the model including fluid electrons and gas-phase chemistry. The addition of more complex physics will greatly extend the capability of the application of particle kinetic methods to even more realistic and practical problems. |
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