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Effects of eddy viscosity on time correlations in large eddy simulation
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Rubinstein, R. He, Guowei Wang, Lian-Ping |
| Copyright Year | 2001 |
| Description | 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 application- 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. Tile 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. |
| File Size | 525749 |
| Page Count | 12 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20010048921 |
| Archival Resource Key | ark:/13960/t6m092d71 |
| Language | English |
| Publisher Date | 2001-05-01 |
| Access Restriction | Open |
| Subject Keyword | Fluid Mechanics And Thermodynamics Correlation Turbulent Flow Direct Numerical Simulation Scale Models Backscattering Estimates Eddy Viscosity Viscous Drag Reynolds Stress Large Eddy Simulation Acoustic Simulation Vortices Isotropic Turbulence Frequency Distribution Kinetic Energy Energy Transfer Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Technical Report |
