Switching criteria for hybrid rarefied gas flow solvers
Switching criteria for hybrid rarefied gas flow solvers
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DOI：
10.1098/rspa.2008.0497
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发表时间：
2009-01
期刊：
影响因子：
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通讯作者：
D. Lockerby;J. Reese;H. Struchtrup
中科院分区：
文献类型：
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作者：
D. Lockerby;J. Reese;H. Struchtrup
开发了混合流体动力学/分子气体流动求解器的切换标准，并被证明比识别热力学非平衡的传统标准更合适。对于从分子/动力学求解器切换到流体动力学（连续流体）求解器，该标准基于流体动力学近平衡通量（即纳维-斯托克斯应力和傅里叶热通量）与分子求解器计算的应力和热通量的实际值之间的差异。为了从流体动力学切换到分子/动力学，使用类似的标准，但应力和热通量的值通过高阶本构关系来近似；在本例中，我们使用 R13 方程。我们提出的切换标准的有效性在示例性混合动力学/纳维-斯托克斯求解器中进行了测试。对于所研究的测试用例，混合程序的结果与完整的动力学解决方案相比非常好，并且只需一小部分计算成本即可获得。
Switching criteria for hybrid hydrodynamic/molecular gas flow solvers are developed, and are demonstrated to be more appropriate than conventional criteria for identifying thermodynamic non-equilibrium. For switching from a molecular/kinetic solver to a hydrodynamic (continuum-fluid) solver, the criterion is based on the difference between the hydrodynamic near-equilibrium fluxes (i.e. the Navier–Stokes stress and Fourier heat flux) and the actual values of stress and heat flux as computed from the molecular solver. For switching from hydrodynamics to molecular/kinetic, a similar criterion is used but the values of stress and heat flux are approximated through higher order constitutive relations; in this case, we use the R13 equations. The efficacy of our proposed switching criteria is tested within an illustrative hybrid kinetic/Navier–Stokes solver. For the test cases investigated, the results from the hybrid procedure compare very well with the full kinetic solution, and are obtained at a fraction of the computational cost.