The 'upstream wake' of swimming and flying animals and its correlation with propulsive efficiency
- Creators
- Peng, Jifeng
- Dabiri, John O.
Abstract
The interaction between swimming and flying animals and their fluid environments generates downstream wake structures such as vortices. In most studies, the upstream flow in front of the animal is neglected. In this study, we demonstrate the existence of upstream fluid structures even though the upstream flow is quiescent or possesses a uniform incoming velocity. Using a computational model, the flow generated by a swimmer (an oscillating flexible plate) is simulated and a new fluid mechanical analysis is applied to the flow to identify the upstream fluid structures. These upstream structures show the exact portion of fluid that is going to interact with the swimmer. A mass flow rate is then defined based on the upstream structures, and a metric for propulsive efficiency is established using the mass flow rate and the kinematics of the swimmer. We propose that the unsteady mass flow rate defined by the upstream fluid structures can be used as a metric to measure and objectively compare the efficiency of locomotion in water and air.
Additional Information
Published by The Company of Biologists 2008. Accepted 18 May 2008. Accepted 18 May 2008. We thank Dr Robert Krasny, Dr Jeff Eldredge and Dr Ratnesh Shukla for discussions of the vortex sheet method. We also thank Dr George Lauder for discussions of eel swimming. We gratefully acknowledge financial support from the National Science Foundation programs in Biological Oceanography (OCE-0623475, OCE-0727825) and Energy for Sustainability (CBET-0725164) and an ONR Young Investigator Program award (to J.O.D.). Supplementary material available online at http://jeb.biologists.org/cgi/content/full/211/16/2669/DC1.Attached Files
Published - PENjeb08b.pdf
Supplemental Material - PENjeb08bmovie1.mpg
Supplemental Material - PENjeb08bmovie2.mpg
Supplemental Material - PENjeb08bmovie3.mpg
Supplemental Material - PENjeb08bmovie4.mpg
Supplemental Material - PENjeb08bmovie5.mpg
Supplemental Material - PENjeb08bmovie6.mpg
Supplemental Material - PENjeb08bmovie7.mpg
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Additional details
- Eprint ID
- 12142
- Resolver ID
- CaltechAUTHORS:PENjeb08b
- OCE-0623475
- NSF
- OCE-0727825
- NSF
- CBET-0725164
- NSF
- Office of Naval Research (ONR)
- Created
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2008-10-24Created from EPrint's datestamp field
- Updated
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2021-11-08Created from EPrint's last_modified field