Lloyd, CJ, Peakall, J orcid.org/0000-0003-3382-4578, Burns, A et al. (4 more authors) (2021) Hydrodynamic efficiency in sharks: the combined role of riblets and denticles. Bioinspiration & Biomimetics. ISSN 1748-3182
Abstract
We investigate the influence of smooth and ribletted shark skin on a turbulent boundary layer flow. Through Laser Doppler Anemometry the role of riblets in combination with the shark skin denticle is established for the first time. Our results show that smooth denticles behave like a typical rough surface when exposed to an attached boundary layer. Drag is increased for the full range of tested dimensionless denticle widths, w+≈ 25-80, where w+is the denticle width, w, scaled by the friction velocity, uτ, and the kinematic viscosity, ν. However, when riblets are added to the denticle crown we demonstrate there is a significant reduction in drag, relative to the smooth denticles. We obtain a modest maximum drag reduction of 2 % for the ribletted denticles when compared to the flat plate, but when compared to the smooth denticles the difference in drag is in excess of 20 % for w+≈ 80. This study enables a new conclusion that riblets have evolved as a mechanism to reduce or eliminate the skin friction increase due to the presence of scales (denticles). The combination of scales and riblets is hydrodynamically efficient in terms of skin-friction drag, while also acting to maintain flow attachment, and providing the other advantages associated with scales, e.g. anti-fouling, abrasion resistance, and defence against parasites.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2021 The Author(s). Published by IOP Publishing Ltd. This is an open access article under the terms of the Creative Commons Attribution License (CC-BY 4.0). |
Keywords: | Boundary layer; Drag reduction; Shark skin denticles |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Institute for Applied Geosciences (IAG) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 06 May 2021 08:04 |
Last Modified: | 06 May 2021 08:04 |
Status: | Published online |
Publisher: | IOP Publishing |
Identification Number: | 10.1088/1748-3190/abf3b1 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:173716 |
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