An Investigation of Dolphin-Groove Inspired Surface Patterning on Flow Control

A problem in many flow applications is boundary layer separation; this study investigates the passive separation control mechanism that could result from the micro-grooves found on dolphin skin (Tursiops truncates). A water tunnel was used to study a turbulent boundary layer over rigid 3D printed plastic models, and an adverse pressure gradient was created with a rotating cylinder to induce flow separation in the region of study. Each model consists of dynamically similar sinusoidal grooves in the streamwise direction inspired by dolphin skin. The groove period for this study is 5 mm, and the groove amplitude (A) to period (P) ratio is varied by 0.1, 0.18, and 0.3. The hypothesis is that the dolphin-inspired case (0.18) will lead to maximal flow separation control with minimal skin friction drag penalty. Time-resolved digital particle image velocimetry (TR-DPIV) was used to track the development of the flow separation within the boundary layer and compared to the smooth plate (non-grooved) wall cases. The grooved surfaces form embedded vortices within the sinusoidal cavities which can lead to a partial slip condition effect in the wall vicinity. DPIV results quantify momentum adjacent to the grooved surface and the corresponding flow separation. Separation is quantified by length and the location and height of the maximum separation. The A/P = 0.18 protruding case corresponding to the biological inspiration, and the A/P = 0.1 protruding case proved to be the most effective in increasing momentum near the wall through vortex formation in the cavity resulting in a partial slip condition that significantly decreased the separation. The A/P = 0.3 case protrudes higher into the boundary layer, causing turbulent mixing to prevent maximum flow control. Finally, embedded grooves with negative offset do not appear more successful in flow control than protruding grooves.

Grantor dc:publisher

University of Alabama Libraries

Year dc:date.issued

2024

Author dc:creator

• Hill, Emma Rose

Advisor dc:contributor.advisor

• Lang, Amy W.

Contributors dc:contributor

• Hubner, James P.
• Agrawal, Ajay K.

• Adverse pressure
• Bio-inspired
• Dolphin grooves
• Flow separation

Statement dc:rights

• All rights reserved by the author unless otherwise indicated.

Language dc:language.iso

en_US, English

Dc Identifier Other

1088587

OAI identifier oai:identifier

oai:ir.ua.edu:123456789/14436