Investigation of large-scale coherence in a turbulent boundary layer using two-point correlations

Abstract

Stereoscopic particle image velocimetry (PIV) measurements are made in streamwise-spanwise and inclined cross-stream planes (inclined at 45° and 135° to the principal flow direction) of a turbulent boundary layer at moderate Reynolds number (Reτ ∼ 1100). Two-point spatial velocity correlations computed using the PIV data reveal results that are consistent with an earlier study in which packets of hairpin vortices were identified by a feature-detection algorithm in the log region, but not in the outer wake region. Both streamwise-streamwise (Ruu) and streamwise-wall-normal (Ruw) correlations are significant for streamwise displacements of more than 1500 wall units. Zero crossing data for the ..