Abstract:
In this paper, a PIV system is used to measure the scales oflarge scale coherent structures in the turbulent boundary layer of a flatplate. The streamwise and spanwise scales of coherent structures atRe_\theta =628.5 and 1032.9 are obtained by wavelet analysis andtraditional statistic methods. Multi-scalespatial vector distributions of \pmb u', \pmb v' and \d \pmbv' / \d \pmb x obtained by wavelet analysis in theturbulent boundary layer at Re_\theta =628.5 are used to verify the SLscaling law and the self-similarity law. It is found that at asingle scale of the flow field, the three statistical structures are matchedwell with the SL law and the self-similarity law, respectively, but theparameters of the SL law are not unique, but varying with flow scales.From the relation between S_5, and l (the distance), inertia ranges are foundnot the same for the SL scaling law and the self-similarity law, butvarying also with the scale.