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Cell Aspect Ratio Dependence of Anisotropy Measures for Resolved and Subgrid Scale Stresses
Discrete approximation of a flow field using anisotropic meshes causes “unphysical” anisotropy of the resolved part of the Reynolds stress tensor and of the subgrid scale stress tensor if common anisotropy measures such asūı̄ūj/q2− 1/3δijare used in order to characterize the turbulence structure. By...
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Published in: | Journal of computational physics 1997-09, Vol.136 (2), p.399-410 |
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Main Author: | |
Format: | Article |
Language: | English |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Discrete approximation of a flow field using anisotropic meshes causes “unphysical” anisotropy of the resolved part of the Reynolds stress tensor and of the subgrid scale stress tensor if common anisotropy measures such asūı̄ūj/q2− 1/3δijare used in order to characterize the turbulence structure. By evaluating model spectrum tensors the effect is investigated for isotropic and anisotropic turbulence. The deviation from a physical meaningful anisotropy state depends on various parameters such as the energy spectrum shape near the cutoff in wavespace, the cell aspect ratios, and the range of scales which are resolved. Subgrid kinetic energy must be distributed unequally among the normal stresses on an anisotropic mesh. For example, for aspect ratios Δx:Δy:Δz= 1:8:4, rms fluctuations of subgrid motions are shown to deviate by 9% in isotropic turbulence in the inertial subrange. |
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ISSN: | 0021-9991 1090-2716 |
DOI: | 10.1006/jcph.1997.5755 |