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Analysis of anisotropically permeable surfaces for turbulent drag reduction

Abderrahaman-Elena, N and García-Mayoral, R (2017) Analysis of anisotropically permeable surfaces for turbulent drag reduction. Physical Review Fluids, 2. ISSN 2469-990X

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The present work proposes the use of anisotropically permeable substrates as a means to reduce turbulent skin friction. We conduct an a priori analysis to assess the potential of these surfaces, based on the effect of small-scale surface manipulations on near-wall turbulence. The analysis, valid for small permeability, predicts a monotonic decrease in friction as the streamwise permeability increases. Empirical results suggest that the drag-reducing mechanism is however bound to fail beyond a certain permeability. We investigate the development of Kelvin-Helmholtz-like rollers at the surface as a potential mechanism for this failure. These rollers, which are a typical feature of turbulent flows over permeable walls, are known to increase drag and their appearance is known to limit the drag-reducing effect. We propose a model, based on linear stability analysis, that predicts the onset of these rollers for sufficiently large permeability and allows us to bound the maximum drag reduction that these surfaces can achieve.

Item Type: Article
Divisions: Div A > Fluid Mechanics
Depositing User: Cron Job
Date Deposited: 25 Oct 2017 20:05
Last Modified: 15 Apr 2021 05:55
DOI: 10.1103/PhysRevFluids.2.114609