Statistics of velocity gradients in wall-bounded shear flow turbulence

PHYSICA D-NONLINEAR PHENOMENA

卷:239

Article; Proceedings Paper

Boeck, Thomas¹  Krasnov, Dmitry¹  Schumacher, Joerg¹ 

[1] Tech Univ Ilmenau, Inst Thermodynam & Fluid Mech, D-98684 Ilmenau, Germany

关键词: Turbulent shear flows;    Energy dissipation rate;    Enstrophy;   

DOI  :  10.1016/j.physd.2009.10.004

来源: Elsevier

【 摘 要 】

The statistical properties of velocity gradients in a wall-bounded turbulent channel flow are discussed on the basis of three-dimensional direct numerical simulations. Our analysis is concentrated on the trend of the statistical properties of the local enstrophy omega(2)(x, t) and the energy dissipation rate epsilon(x, t) with increasing distance from the wall. We detect a sensitive dependence of the largest amplitudes of both fields (which correspond with the tail of the distribution) on the spectral resolution. The probability density functions of each single field as well as their joint distribution vary significantly with increasing distance from the wall. The largest fluctuations of the velocity gradients are found in the logarithmic layer. This is in agreement with recent experiments which observe a bursting of hairpin vortex packets into the logarithmic region. (C) 2009 Elsevier B.V. All rights reserved.

【 授权许可】

Free