Journal article

Turbulent structures in a statistically three-dimensional boundary layer

undefined Kevin, Jason Monty, Nicholas Hutchins

Journal of Fluid Mechanics | Cambridge University Press (CUP) | Published : 2019

Abstract

We investigate the behaviour of large-scale coherent structures in a spanwise-heterogeneous turbulent boundary layer, using particle image velocimetry on multiple orthogonal planes. The statistical three-dimensionality is imposed by a herringbone riblet surface, although the key results presented here will be common to many cases of wall turbulence with embedded secondary flows in the form of mean streamwise vortices. Instantaneous velocity fields in the logarithmic layer reveal elongated low-momentum streaks located over the upwash-flow region, where their spanwise spacing is forced by the 2δ periodicity of the herringbone pattern. These streaks largely resemble the turbulence structures th..

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Grants

Funding Acknowledgements

The authors wish to thank the Australian Research Council for the financial support of this research. The authors also wish to thank H. L. Bai for providing valuable discussions, and B. Nugroho for sharing the test surface. We are also grateful to K. Christensen for hosting the collaborative experiments that produced the cross-plane views reproduced in this paper.