Home Books eBooks Journals References & Proceedings Authors, Editors, Reviewers A-Z Product Index Awards
Turbulence and Shear Flow Phenomena -1 First International Symposium

ISBN:
1-56700-135-1 (Print)

NEAR-WALL TURBULENCE STRUCTURES IN THREE-DIMENSIONAL BOUNDARY LAYERS

Anh-Tuan Le
Department of Mechanical & Aerospace Engineering, UCLA Los Angeles, California, 90095-1597, USA

Gary N. Coleman
School of Engineering Sciences, University of Southampton Highfield, Southampton, Hampshire, SO17 1BJ, UK

John Kim
Mechanical and Aerospace Department University of California, Los Angeles 420 Westwood Plaza, Los Angeles CA 90095-1597, USA

Abstract

In this study we examine the structure of near-wall turbulence in three-dimensional boundary layers (3DBLs), which we approximate by applying an impulsive spanwise motion to the lower wall of a turbulent channel flow. Direct numerical simulation (DNS) data are analyzed using Reynolds stress budgets, probability density functions (PDFs) and conditional-averaged quadrant analysis about strong sweeps and ejections, and visualization of vortices with the λ2 criterion. The evidence suggests that mean three-dimensionality breaks up the symmetry and alignment of near-wall structures, disrupting their 'self-sustaining mechanisms', and thereby causing a reduction in the turbulence kinetic energy (TKE).