Journal article

The effect of spanwise wavelength of surface heterogeneity on turbulent secondary flows

DD Wangsawijaya, R Baidya, D Chung, I Marusic, N Hutchins

Journal of Fluid Mechanics | Cambridge University Press (CUP) | Published : 2020

Abstract

We examine the behaviour of turbulent boundary layers over surfaces composed of spanwise-alternating smooth and rough strips, where the width of the strips varies such that, where is the boundary-layer thickness averaged over one spanwise wavelength of the heterogeneity. The experiments are configured to examine the influences of spanwise variation in wall shear stress over a large range. Hot-wire anemometry and particle image velocimetry (PIV) reveal that the half-wavelength governs the diameter and strength of the resulting mean secondary flows and hence the observed isovels of the mean streamwise velocity. Three possible cases are observed: limiting cases (either or), where the secondary ..

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Grants

Awarded by Australian Research Council


Awarded by Office of Naval Research


Funding Acknowledgements

This research is supported by the Australian Research Council Discovery Project (DP160102279) and the Office of Naval Research (BRC N00014-17-1-2307).