Near-wall turbulence structures in three-dimensional boundary layers

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 analysed using probability density functions (PDFs), conditional-averaged quadrant analysis about Reynolds-stress-producing events. and visualization of vortices with the lambda(2)-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). (C) 2000 Begell House Inc. Published by Elsevier Science Inc. All rights reserved.