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### ·s»D¼ÐÃD¡G¡@( 2010-05-06 )

ºtÁ¿¥DÃD¡GNumerical modelling of gas flow with kinetic theory methods with some recent results on modelling viscosity

¥DÁ¿¤H¡GDr. Mark Jermy (University of Canterbury, New Zealand)

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Numerical modelling of fluid flow has many important applications in industrial processes, vehicle design, weather prediction and the study of turbulence. Conventional computational fluid mechanics (CFD) methods are based on solving continuum conservation equations such as the Euler or Navier-Stokes equations. Some difficulties with these methods persist: the solution is sensitive to the orientation of the grid, convergence is uncertain, and the computational expense is high for many practical problems.

Kinetic theory methods may offer solutions to these problems. Direct Simulation Monte Carlo (DSMC) has shown great accuracy and versatility, particulaly in rarefied or nonequilibrium flows, but has a very high computational expense. The Lattice Boltzmann Method (LBM) has been particuarly successful in flows where mesoscopic physics is important e.g. the flow of immiscible fluids.

Quiet Direct Simulation (QDS) is a numerical scheme based in kinetic theory, sharing some aspects with LBM and having been proven fast and relatively accurate in compressible flows. The basic scheme shows high dissipation which limits it's application to low speed viscous flows.

The theoretical and numerical basis of the scheme will be described and linked to related schemes. The causes of the hgih dissipation will be discussed and the results of some possible solutions, yet at the testing stage, will be presented.