Abstract
On the basis of (i) particle image velocimetry data of a turbulent boundary layer with large field of view and good spatial resolution and (ii) a mathematical relation between the energy spectrum and specifically modeled flow structures, we show that the scalings of the streamwise energy spectrum in a wave-number range directly affected by the wall are determined by wall-attached eddies but are not given by the Townsend-Perry attached eddy model's prediction of these spectra, at least at the Reynolds numbers considered here which are between and . Instead, we find where varies smoothly with distance to the wall from negative values in the buffer layer to positive values in the inertial layer. The exponent characterizes the turbulence levels inside wall-attached streaky structures conditional on the length of these structures. A particular consequence is that the skin friction velocity is not sufficient to scale for wave numbers directly affected by the wall.
11 More- Received 13 November 2017
DOI:https://doi.org/10.1103/PhysRevE.97.053103
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