• Research paper •

### Experimental studies on SL scaling law and spatial scales of coherent structures in near-wall turbulent boundary layer

Wei Zhao

• Received:2005-05-08 Revised:2005-10-19 Online:2007-01-18 Published:2007-01-18

Abstract: In this paper, a PIV system is used to measure the scales of large scale coherent structures in the turbulent boundary layer of a flat plate. The streamwise and spanwise scales of coherent structures at Re_{\theta }=628.5 and 1032.9 are obtained by wavelet analysis and traditional statistic methods. Multi-scale spatial vector distributions of {\pmb u}', {\pmb v}' and \d {\pmb v}' / \d {\pmb x} obtained by wavelet analysis in the turbulent boundary layer at Re_{\theta }=628.5 are used to verify the SL scaling law and the self-similarity law. It is found that at a single scale of the flow field, the three statistical structures are matched well with the SL law and the self-similarity law, respectively, but the parameters 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 found not the same for the SL scaling law and the self-similarity law, but varying also with the scale.