Effects of eddy viscosity on time correlations in large eddy simulation

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	Effects of eddy viscosity on time correlations in large eddy simulation
	He GW(何国威); Rubinstein R; Wang LP
	2001
出处	何国威;Rubinstein R;Wang LP.Effects of eddy viscosity on time correlations in large eddy simulation:2001.
关键词	Eddy Viscosity Time Correlation Large Eddy Simulation
英文摘要	Subgrid-scale (SGS) models for large eddy simulation (LES) have generally been evaluated by their ability to predict single-time statistics of turbulent flows such as kinetic energy and Reynolds stresses. Recent applications of large eddy simulation to the evaluation of sound sources in turbulent flows, a problem in which time correlations determine the frequency distribution of acoustic radiation, suggest that subgrid models should also be evaluated by their ability to predict time correlations in turbulent flows. This paper compares the two-point, two-time Eulerian velocity correlation evaluated from direct numerical simulation (DNS) with that evaluated from LES, using a spectral eddy viscosity, for isotropic homogeneous turbulence. It is found that the LES fields are too coherent, in the sense that their time correlations decay more slowly than the corresponding time correlations in the DNS fields. This observation is confirmed by theoretical estimates of time correlations using the Taylor expansion technique. The reason for the slower decay is that the eddy viscosity does not include the random backscatter, which decorrelates fluid motion at large scales. An effective eddy viscosity associated with time correlations is formulated, to which the eddy viscosity associated with energy transfer is a leading order approximation.
文献类型	研究报告
条目标识符	http://dspace.imech.ac.cn/handle/311007/44606
专题	力学所知识产出(1956-2008)
推荐引用方式 GB/T 7714	He GW,Rubinstein R,Wang LP. Effects of eddy viscosity on time correlations in large eddy simulation. 2001.

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