EXPERIMENTAL SUPPORT FOR THE ATTACHED-EDDY HYPOTHESIS IN ZERO-PRESSURE-GRADIENT TURBULENT BOUNDARY-LAYERS

Turbulent boundary layer experiments have been conducted at various Reynolds numbers on smooth walls and also on ‘k-type’ and ‘d-type’ rough walls. Both the spectral results and the broadband turbulence intensity results strongly support the Townsend (1976) attached eddy hypothesis and the Perry & Chong (1982) model. The spectral results obtained using the ‘flying’ hot-wire technique show the errors involved when using Taylor’s (1938) hypothesis for converting the spectra from the frequency domain to the wavenumber domain. If the viscous dissipation spectral region is taken into account, the broadband turbulence intensity results agree well with the attached eddy hypothesis. The inconsistency of the various constants given in Perry, Lim & Henbest (1987) for the smooth and rough walls has been explained and removed. Lack of spatial resolution of the hot wires explains to some extent the scatter in the turbulence intensity of the component normal to the wall. This spatial resolution effect is most pronounced in the near-wall region at high Reynolds number and has been corrected by using the method of Wyngaard (1968). © 1990, Cambridge University Press. All rights reserved.