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arXiv 2006.11115physics.flu-dynphysics.comp-ph
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作为数值解的矩量法:来自激波结构问题的挑战

Moment method as a numerical solver: Challenge from shock structure problems

Zhenning Cai

摘要:

我们调查了一些时刻的层次和测试他们的表现在计算一维激波结构。结果发现,对于高马赫数,时刻的层次是计算昂贵或难以收敛,使这些方法的高度非平衡流的模拟值得怀疑。通过研究Grad矩方法的收敛性问题,我们提出了一个新的矩层次来桥接流体动力学模型和动力学方程,允许非线性矩方法作为一种数值工具来离散高速流的速度空间。对于一维速度的情况,该方法是针对奇数阶矩的,并且可以无缝地推广到三维的情况。数值试验表明,该方法能够准确预测高马赫数的激波结构,且随着矩数的增加,计算结果收敛于Boltzmann方程的解。本文还考虑了激波结构问题以外的一些应用,表明本文方法适用于过渡流的计算。

英文摘要:

We survey a number of moment hierarchies and test their performances in computing one-dimensional shock structures. It is found that for high Mach numbers, the moment hierarchies are either computationally expensive or hard to converge, making these methods questionable for the simulation of highly non-equilibrium flows. By examining the convergence issue of Grad's moment methods, we propose a new moment hierarchy to bridge the hydrodynamic models and the kinetic equation, allowing nonlinear moment methods to be used as a numerical tool to discretize the velocity space for high-speed flows. For the case of one-dimensional velocity, the method is formulated for odd number of moments, and it can be extended seamlessly to the three-dimensional case. Numerical tests show that the method is capable of predicting shock structures with high Mach numbers accurately, and the results converge to the solution of the Boltzmann equation as the number of moments increases. Some applications beyond the shock structure problem are also considered, indicating that the proposed method is suitable for the computation of transitional flows.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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