报告题目: |
On the Potential Abilities of Artificial Compressibility Method |
报告人: |
Taku Ohwada |
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Professor
Department of Aeronautics and Astronautics,
Graduate School of Engineering, Kyoto University
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报告时间: |
2009-07-20 10:00 |
报告地点: |
逸夫技术科学楼3214会议室 |
主办单位: |
航天航空学院 |
简介: |
The main target fluid of Lattice Boltzmann Method (LBM) is the incompressible viscous fluid. The advantage of LBM is that the pressure field is determined evolutionally and its computation procedure is very simple and suitable for parallel computation. On the other hand, the artificial compressibility method (ACM), which was developed by Chorin about 40 years ago, has the same advantage. Since ACM deals with a PDE system for macroscopic variables, i.e. the artificial continuity equation and the momentum equation of the incompressible NS system, its asymptotic analysis for small Mach numbers can be done more easily than that of LBM, which means that its education cost is lower than that of LBM. From its asymptotic analysis, LBM can be regarded as a kinetic ACM. However, its advantage over ACM is not very clearly recognized or it is taken for granted. Such a vague settlement is partially due to the lack of clear understanding of the abilities of ACM, which is seen from the fact that ACM is said in the literature to be principally intended to steady flows. In this talk, we will demonstrate numerically the potential abilities of ACM as a numerical method for the time-dependent incompressible Navier-Stokes equations together with the introduction of new techniques of ACM for the increase of the accuracy (4th order in space and second order in time) and the suppression of acoustic mode and checkerboard instability. It will be shown that even a cheap edition of ACM, which employs the same stencil as that of LBM (D2Q9), yields better results than those of one of the most up to date LBMs presently available (MRT with a consistent treatment of forcing). This means that ACM revives as a foe that LBM must defeat! |
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