Taylor’s hypothesis in turbulent channel flow considered using a transport equation analysis
| Autor: | Adrián Lozano-Durán, Chenhui Geng, Chunxiao Xu, James M. Wallace, Guowei He, Yinshan Wang |
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| Rok vydání: | 2015 |
| Předmět: |
Fluid Flow and Transfer Processes
Physics Turbulent diffusion Turbulence Mechanical Engineering Computational Mechanics Reynolds number Mechanics Vorticity Condensed Matter Physics Vortex Open-channel flow Physics::Fluid Dynamics symbols.namesake Classical mechanics Mechanics of Materials symbols Navier–Stokes equations Convection–diffusion equation |
| Zdroj: | Physics of Fluids. 27:025111 |
| ISSN: | 1089-7666 1070-6631 |
| DOI: | 10.1063/1.4908070 |
| Popis: | Direct numerical simulations of turbulent channel flow at Re-tau = 205 and 932 have been carried out to examine Taylor's "frozen turbulence" hypothesis. The terms in Taylor's hypothesis appear in the transport equation for instantaneous momentum (Navier-Stokes) in this flow. The additional terms, i.e., the additional convective acceleration term and the pressure gradient and viscous force terms, act to diminish the validity of Taylor's hypothesis when they are relatively large compared to the Taylor's hypothesis terms and are not in balance. A similar analysis has been applied to the transport equation for instantaneous vorticity. The additional terms in this equation, namely, the additional convective rates of change of vorticity terms, the stretching/compression/rotation of vorticity terms, and the viscous diffusion of vorticity terms, similarly act to diminish the validity of Taylor's hypothesis when they are relatively large compared to the terms in the hypothesis and are not in balance. Where in the channel flow this diminishment occurs, and to what degree, and which of the non-Taylor's hypothesis terms in the momentum and vorticity equations contribute most to this diminishment are unraveled here. (C) 2015 AIP Publishing LLC. |
| Databáze: | OpenAIRE |
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