Spectral scaling in a high reynolds number laboratory boundary layer |
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Authors: | R A Antonia M R Raupach |
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Institution: | (1) Department of Mechanical Engineering, University of Newcastle, 2308, N.S.W., Australia;(2) Division of Environmental Mechanics, C.S.I.R.O., 2600 Canberra, ACT, Australia |
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Abstract: | Spectra and co-spectra of the streamwise (u) and normal or vertical (w) velocity fluctuations have been measured in the inner region of a large Reynolds number laboratory boundary layer over a rough wall. There is reasonable evidence of ak
1
–1
range in theu spectrum (wherek
1 is the streamwise wavenumber). Such a range results from an overlap between a spectral region dominated by largescale, inactive motion, which scales on the boundary-layer thickness, and a region dominated by smaller-scale, active motion which scales on the distance from the wall. Spectra ofw, anduw cospectra, scale in a manner consistent with the dominance by active motion. The present spectral data do not support local isotropy over the inertial subrange. A comparison between measuredw spectra and calculations based on isotropy indicates that the inertial subrange anisotropy is only slightly affected by the magnitude of the non-dimensional mean shear. |
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Keywords: | |
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