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Published July 2011 | Published + Supplemental Material
Journal Article Open

Characteristics of vortex formation and thrust performance in drag-based paddling propulsion


Several characteristics of drag-based paddling propulsion are studied with a simple mechanical model and a measurement technique for mapping three-dimensional flow fields. In drag-based propulsion, the temporal change of the vortex strength is an important parameter in the relationship between vortex formation and thrust generation. Our results indicate that spanwise flow behind the paddling propulsor significantly affects tip vortex development and thrust generation. The distribution of spanwise flow is dependent on the propulsor shape and the Reynolds number. A delta-shaped propulsor generates strong spanwise flow compared with a rectangular propulsor. For the low Reynolds number case, spanwise flow is not as strong as that for the high Reynolds number case. Without sacrificing total impulse, the flexible propulsor can smooth out thrust peaks during sudden stroke motions, which is favorable for avoiding structural failures and stabilizing body motion. We also explored the role of stopping vortex shedding in efficient thrust generation by determining the relationship between stroke angles and total impulses generated by paddling propulsors.

Additional Information

© 2011 The Company of Biologists Ltd. Accepted 4 April 2011.

Attached Files

Supplemental Material - JEB050716FigS1.jpg

Supplemental Material - JEB050716FigS2.jpg

Supplemental Material - JEB050716FigS3.jpg

Supplemental Material - JEB050716FigS4.jpg

Published - Kim2011p14127J_Exp_Biol.pdf

Supplemental Material - Movie1.mpg

Supplemental Material - Movie2.mpg

Supplemental Material - Movie3.mpg


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August 22, 2023
August 22, 2023