TY - JOUR

T1 - Asymptotic exponents from low-Reynolds-number flows

AU - Schumacher, Jörg

AU - Sreenivasan, Katepalli R.

AU - Yakhot, Victor

N1 - Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.

PY - 2007/4/11

Y1 - 2007/4/11

N2 - The high-order statistics of fluctuations in velocity gradients in the crossover range from the inertial to the Kolmogorov and sub-Kolmogorov scales are studied by direct numerical simulations (DNS) of homogeneous isotropic turbulence with vastly improved resolution. The derivative moments for orders 0 ≤ n ≤ 8 are represented well as powers of the Reynolds number, Re, in the range 380 ≤ Re ≤ 5275, where Re is based on the periodic box length L x. These low-Reynolds-number flows give no hint of scaling in the inertial range even when extended self-similarity is applied. Yet, the DNS scaling exponents of velocity gradients agree well with those deduced, using a recent theory of anomalous scaling, from the scaling exponents of the longitudinal structure functions at infinitely high Reynolds numbers. This suggests that the asymptotic state of turbulence is attained for the velocity gradients at far lower Reynolds numbers than those required for the inertial range to appear. We discuss these findings in the light of multifractal formalism. Our numerical studies also resolve the crossover of the velocity gradient statistics from Gaussian to non-Gaussian behaviour that occurs as the Reynolds number is increased.

AB - The high-order statistics of fluctuations in velocity gradients in the crossover range from the inertial to the Kolmogorov and sub-Kolmogorov scales are studied by direct numerical simulations (DNS) of homogeneous isotropic turbulence with vastly improved resolution. The derivative moments for orders 0 ≤ n ≤ 8 are represented well as powers of the Reynolds number, Re, in the range 380 ≤ Re ≤ 5275, where Re is based on the periodic box length L x. These low-Reynolds-number flows give no hint of scaling in the inertial range even when extended self-similarity is applied. Yet, the DNS scaling exponents of velocity gradients agree well with those deduced, using a recent theory of anomalous scaling, from the scaling exponents of the longitudinal structure functions at infinitely high Reynolds numbers. This suggests that the asymptotic state of turbulence is attained for the velocity gradients at far lower Reynolds numbers than those required for the inertial range to appear. We discuss these findings in the light of multifractal formalism. Our numerical studies also resolve the crossover of the velocity gradient statistics from Gaussian to non-Gaussian behaviour that occurs as the Reynolds number is increased.

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U2 - 10.1088/1367-2630/9/4/089

DO - 10.1088/1367-2630/9/4/089

M3 - Article

AN - SCOPUS:34147223030

VL - 9

JO - New Journal of Physics

JF - New Journal of Physics

SN - 1367-2630

M1 - 89

ER -