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Spectral Analysis of the Slip-Length Model for Turbulence over Textured Superhydrophobic Surfaces.

Published version
Peer-reviewed

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Authors

García-Mayoral, R 

Abstract

We assess the applicability of slip-length models to represent textured superhydrophobic surfaces. From the results of direct numerical simulations, and by considering the slip length from a spectral perspective, we discriminate between the apparent boundary conditions experienced by different lengthscales in the overlying turbulent flow. In particular, we focus on the slip lengths experienced by lengthscales relevant to the near wall turbulent dynamics. Our results indicate that the apparent failure of homogeneous slip-length models is not the direct effect of the texture size becoming comparable to the size of eddies in the flow. The texture-induced signal scatters to the entire wavenumber space, affecting the perceived slip length across all lengthscales, even those much larger than the texture. We propose that the failure is caused by the intensity of the texture-induced flow, rather than its wavelength, becoming comparable to the background turbulence.

Description

Keywords

Drag reduction, Superhydrophobic surfaces, Turbulent boundary layers

Journal Title

Flow Turbul Combust

Conference Name

Journal ISSN

1386-6184
1573-1987

Volume Title

100

Publisher

Springer Science and Business Media LLC
Sponsorship
EPSRC (1476425)