Two-point stress–strain-rate correlation structure and non-local eddy viscosity in turbulent flows
| Autor: | Charles Meneveau, Tamer A. Zaki, Patricio Clark Di Leoni, George Em Karniadakis |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Physics
Turbulence Mechanical Engineering Isotropy Turbulence modeling Mechanics Deformation (meteorology) Condensed Matter Physics 01 natural sciences 010305 fluids & plasmas Open-channel flow Physics::Fluid Dynamics 010101 applied mathematics Stress (mechanics) Mechanics of Materials 0103 physical sciences Point (geometry) 0101 mathematics Communication channel |
| Zdroj: | Journal of Fluid Mechanics. 914 |
| ISSN: | 1469-7645 0022-1120 |
| Popis: | By analysing the Karman–Howarth equation for filtered-velocity fields in turbulent flows, we show that the two-point correlation between the filtered strain-rate and subfilter stress tensors plays a central role in the evolution of filtered-velocity correlation functions. Two-point correlation-based statistical a priori tests thus enable rigorous and physically meaningful studies of turbulence models. Using data from direct numerical simulations of isotropic and channel flow turbulence, we show that local eddy-viscosity models fail to exhibit the long tails observed in the real subfilter stress–strain-rate correlation functions. Stronger non-local correlations may be achieved by defining the eddy-viscosity model based on fractional gradients of order yields better results for the correlations in the streamwise direction, even well into the core channel region. In the spanwise direction, channel flow results show significantly more local interactions. The overall results confirm strong non-locality in the interactions between subfilter stresses and resolved-scale fluid deformation rates, but with non-trivial directional dependencies in non-isotropic flows. Hence, non-local operators thus exhibit interesting modelling capabilities and potential for large-eddy simulations although more developments are required, both on the theoretical and computational implementation fronts. |
| Databáze: | OpenAIRE |
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