Comparisons of turbulence stresses fro experiments against the attached eddy hypothesis in boundary layers

Abstract

Turbulence stress statistics in a boundary layer at Reτ ≈ 10,000 are measured using custom X hot-wire probes. The results show logarithmic behaviour in the profiles of the streamwise and span-wise turbulence intensities against wall-normal distance in the same region in which the mean velocity exhibits logarithmic behaviour, consistent with the predictions of the attached eddy hypothesis. Comparisons are drawn with computations applying the attached eddy hypothesis using two different typical representative eddies: (i) hierarchies of individual hairpins and (ii) hierarchies of packets of hairpins. Promising results are obtained when a packet-eddy is used rather than an individual hairpineddy..