TY - JOUR

T1 - Scale dependence of the coarse-grained velocity derivative tensor

T2 - Influence of large-scale shear on small-scale turbulence

AU - Naso, Aurore

AU - Chertkov, Michael

AU - Pumir, Alain

PY - 2006

Y1 - 2006

N2 - We discuss the effect of large-scale anisotropy of the shear type on the small-scale structure of turbulence. Our analysis is based on numerical solutions of the Lagrangian tetrad model of Chertkov M., Pumir A. and Shraiman B.I. (1999, Physics of Fluids, 11, 2394) adapted to the model case with large-scale anisotropy. The model, formulated in terms of a set of stochastic differential equations for the coarse-grained velocity gradient and tensor of inertia of a typical shape, naturally connects Lagrangian and Eulerian parameterizations of turbulence. We use diagnostics of Chertkov et al. (1999) which allows us to analyse and interpret different correlation functions at the resolved scale in terms of the flow geometry. Our main conclusion, concerning the issue of anisotropy, is that even though overall the local isotropy is restored with the scale decrease, the particular pace of the isotropy restoration depends very much on the object analysed. We found that the vorticity-dominated objects, such as enstrophy, tend to restore the isotropy much faster than their strain-dominated counterparts, e.g. energy flux and strain variance.

AB - We discuss the effect of large-scale anisotropy of the shear type on the small-scale structure of turbulence. Our analysis is based on numerical solutions of the Lagrangian tetrad model of Chertkov M., Pumir A. and Shraiman B.I. (1999, Physics of Fluids, 11, 2394) adapted to the model case with large-scale anisotropy. The model, formulated in terms of a set of stochastic differential equations for the coarse-grained velocity gradient and tensor of inertia of a typical shape, naturally connects Lagrangian and Eulerian parameterizations of turbulence. We use diagnostics of Chertkov et al. (1999) which allows us to analyse and interpret different correlation functions at the resolved scale in terms of the flow geometry. Our main conclusion, concerning the issue of anisotropy, is that even though overall the local isotropy is restored with the scale decrease, the particular pace of the isotropy restoration depends very much on the object analysed. We found that the vorticity-dominated objects, such as enstrophy, tend to restore the isotropy much faster than their strain-dominated counterparts, e.g. energy flux and strain variance.

KW - Flow topology

KW - Phenomenological models

KW - Shear turbulence

UR - http://www.scopus.com/inward/record.url?scp=33744498376&partnerID=8YFLogxK

U2 - 10.1080/14685240600754563

DO - 10.1080/14685240600754563

M3 - Article

AN - SCOPUS:33744498376

VL - 7

SP - 1

EP - 11

JO - Journal of Turbulence

JF - Journal of Turbulence

SN - 1468-5248

ER -