Flexible conformable hydrophobized surfaces for turbulent flow drag reduction

Brennan, J, Geraldi, N, Morris, R ORCID: https://orcid.org/0000-0001-5511-3457, Fairhurst, D ORCID: https://orcid.org/0000-0001-5311-0762, McHale, G and Newton, MI ORCID: https://orcid.org/0000-0003-4231-1002, 2015. Flexible conformable hydrophobized surfaces for turbulent flow drag reduction. Scientific Reports, 5. ISSN 2045-2322

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Abstract

In recent years extensive work has been focused onto using superhydrophobic surfaces for drag reduction applications. Superhydrophobic surfaces retain a gas layer, called a plastron, when submerged underwater in the Cassie-Baxter state with water in contact with the tops of surface roughness features. In this state the plastron allows slip to occur across the surface which results in a drag reduction. In this work we report flexible and relatively large area superhydrophobic surfaces produced using two different methods: Large roughness features were created by electrodeposition on copper meshes; Small roughness features were created by embedding carbon nanoparticles (soot) into Polydimethylsiloxane (PDMS). Both samples were made into cylinders with a diameter under 12 mm. To characterize the samples, scanning electron microscope (SEM) images and confocal microscope images were taken. The confocal microscope images were taken with each sample submerged in water to show the extent of the plastron. The hydrophobized electrodeposited copper mesh cylinders showed drag reductions of up to 32% when comparing the superhydrophobic state with a wetted out state. The soot covered cylinders achieved a 30% drag reduction when comparing the superhydrophobic state to a plain cylinder. These results were obtained for turbulent flows with Reynolds numbers 10,000 to 32,500.

Item Type:	Journal article
Publication Title:	Scientific Reports
Creators:	Brennan, J., Geraldi, N., Morris, R., Fairhurst, D., McHale, G. and Newton, M.I.
Publisher:	Nature Publishing Group
Date:	2015
Volume:	5
ISSN:	2045-2322
Identifiers:	Number Type 10.1038/srep10267 DOI
Rights:	© 2015 Macmillan Publishers Limited. All Rights Reserved.
Divisions:	Schools > School of Science and Technology
Record created by:	EPrints Services
Date Added:	09 Oct 2015 10:52
Last Modified:	09 Jun 2017 13:43
URI:	https://irep.ntu.ac.uk/id/eprint/19430

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