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The 'upstream wake' of swimming and flying animals and its correlation with propulsive efficiency

Peng, Jifeng and Dabiri, John O. (2008) The 'upstream wake' of swimming and flying animals and its correlation with propulsive efficiency. Journal of Experimental Biology, 211 (16). pp. 2669-2677. ISSN 0022-0949. http://resolver.caltech.edu/CaltechAUTHORS:PENjeb08b

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[img] Video (MPEG) (Movie 1. Three flapping kinematics used in the study. Red, kinematics 1 listed in Table 1; black, kinematics 2; green, kinematics 3.) - Supplemental Material
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[img] Video (MPEG) (Movie 2. The locomotion of the model swimmer and the velocity field (vector plot) and the vortex sheet (blue curve).) - Supplemental Material
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[img] Video (MPEG) (Movie 3. Temporal evolution of the FTLE fields and corresponding LCS curves. Blue, backward-time FTLE; red, forward-time FTLE.) - Supplemental Material
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[img] Video (MPEG) (Movie 4. Temporal evolution of the upstream wake. Fluid particles in each of three adjacent repelling LCS are labeled magenta or green in order to track their evolution.) - Supplemental Material
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[img] Video (MPEG) (Movie 5. Temporal evolution of upstream adjacent fluid parcels with a horizontal interface.) - Supplemental Material
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[img] Video (MPEG) (ovie 6. Temporal evolution of upstream adjacent fluid parcels with a vertical interface. After interaction with the swimmer, the particles in the adjacent parcels exhibit substantial deformation and mixing in the vicinity of the attracting LCS.) - Supplemental Material
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[img] Video (MPEG) (Movie 7. Fluid structure in the empiriemcally measured flow about a free-swimming Aurelia aurita jellyfish.) - Supplemental Material
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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.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1242/jeb.015883DOIArticle
http://jeb.biologists.org/cgi/content/abstract/211/16/2669PublisherArticle
http://jeb.biologists.org/cgi/content/full/211/16/2669/DC1PublisherSupporting Information
ORCID:
AuthorORCID
Dabiri, John O.0000-0002-6722-9008
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.
Funders:
Funding AgencyGrant Number
NSFOCE-0623475
NSFOCE-0727825
NSFCBET-0725164
Office of Naval Research (ONR)UNSPECIFIED
Subject Keywords:wake, upstream, fluid dynamics, locomotion
Issue or Number:16
Record Number:CaltechAUTHORS:PENjeb08b
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:PENjeb08b
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:12142
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:24 Oct 2008 23:32
Last Modified:23 Apr 2019 21:05

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