Experimental Investigations into Shark Skin Inspired Active Flow Control Mechanisms

A method for reducing flow separation with actively actuated flaps inspired by bristlingshark scales was studied experimentally using digital particle image velocimetry (DPIV).The flaps in this study had a rectangular shape and were designed with a protrusion heightin the bottom 10% of the boundary layer height, which is similar to that of the flexiblescales found on the mako shark. The flaps were embedded into a flat plate, actuated inunison with frequencies from 0.48 Hz to 5.13 Hz within a water tunnel in a separating turbulent boundary layer flow. These tests were then compared to a corresponding smoothplate case. In the first set of tests, a zero pressure gradient case, it was found that the actuation of the flaps increased the overall momentum in the boundary layer near the wall,when compared to the flat plate case. This momentum increase helps support the hypothesis that the flexible scales of the mako shark help to energize the boundary layer whenself-actuated by the flow. In the second set of tests the model was placed in a separatedregion induced by a rotating cylinder to impose the presence of an adverse pressure gradient. The cases with the actuating flaps showed a reduction in the size of the separatedregion compared to the smooth wall case. These results suggest that the bristling actionof the scales induce mixing within the turbulent boundary layer and is thus an importantcomponent of the mechanism by which flexible shark scales control flow separation.

Grantor dc:publisher

University of Alabama Libraries

Year dc:date.issued

2022

Author dc:creator

• Cross, Adam

Advisor dc:contributor.advisor

• Lang, Amy

Contributors dc:contributor

• Olcmen, Semih
• Agrawal, Ajay

• Bio-inspired
• Flow Control
• Fluid mechanics

Statement dc:rights

• All rights reserved by the author unless otherwise indicated.

Language dc:language.iso

en_US, English

Dc Identifier Other

http://purl.lib.ua.edu/184255
u0015_0000001_0004304
Cross_alatus_0004M_14727

OAI identifier oai:identifier

oai:ir.ua.edu:123456789/8522