Experimental study of a high Reynolds number turbulent boundary layer evolving over a rough-to-smooth change in surface condition

Conference paper (2019)

Authors

Mogeng Li University of Melbourne
Charitha M. De Silva University of Melbourne, University of New South Wales
Rio Baidya University of the Federal Armed Forces Munich, University of Melbourne
D. Chung University of Melbourne
Ivan Marusic University of Melbourne
N. Hutchins University of Melbourne
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Published Date

2019

Language

English

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Abstract

The evolution of turbulent boundary layers downstream of a rough-to-smooth transition is investigated at a range of Reynolds numbers. Measurements are performed at friction Reynolds numbers of 4100, 7100, 14000 and 21000 using hotwire anemometry. The wall-shear stress on the smooth surface in each case is measured directly using oil film interferometry. The growth of the internal layer is studied, and a full recovery of all energetic scales in the energy spectrum of the streamwise velocity fluctuations is observed at 80 boundary layer thicknesses downstream of the roughness transition. A comparison of recovery lengths required for various flow statistics (skin-friction coefficient and energy spectrum) is also presented.