Large scale organization of a near wall turbulent boundary layer

Abstract

An experimental database at a Reynolds number Reθ based on momentum thickness close to 9800, was obtained in the Laboratoire de Mécanique de Lille wind tunnel with stereo-PIV (SPIV) and Hot Wires Anemometry (HWA) (Delville et al., wallturb joined experiment to assess the large scale structures in a high reynolds number turbulent boundary layer. In: Progress in Wall Turbulence: Understanding and Modeling. Springer; 2011. p. 65–73.); using a Linear Stochastic Estimation procedure based on correlations computation, a 3 component field is reconstructed here at high frequency from stereo-PIV at 4 Hz and hot wire data at 30 kHz. The present paper describes the results obtained on large scale coherent structures (uniform momentum regions and vortices) by post-processing this reconstruction. Structures are characterized (size, intensity and life time), and results are discussed with emphasis on the spatio-temporal organization of the coherent structures and their energetic contribution to the flow.