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Three-dimensional flow structures and vorticity control in fish-like swimming

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Show simple item record Zhu, Q. Wolfgang, M.J. Yue, D.K.P. Triantafyllou, M.S. 2005-08-23T06:07:50Z 2005-08-23T06:07:50Z 2002
dc.description.abstract We employ a three-dimensional, nonlinear inviscid numerical method, in conjunction with experimental data from live fish and from a fish-like robotic mechanism, to establish the three-dimensional features of the flow around a fish-like body swimming in a straight line, and to identify the principal mechanisms of vorticity control employed in fish-like swimming. The computations contain no structural model for the fish and hence no recoil correction. First, we show the near-body flow structure produced by the travelling-wave undulations of the bodies of a tuna and a giant danio. As revealed in cross-sectional planes, for tuna the flow contains dominant features resembling the flow around a two-dimensional oscillating plate over most of the length of the fish body. For the giant danio, on the other hand, a mixed longitudinal-transverse structure appears along the hind part of the body. We also investigate the interaction of the body-generated vortices with the oscillating caudal fin and with tail-generated vorticity. Two distinct vorticity interaction modes are identified: the first mode results in high thrust and is generated by constructive pairing of body-generated vorticity with same-sign tail-generated vorticity, resulting in the formation of a strong thrust wake; the second corresponds to high propulsive efficiency and is generated by destructive pairing of body-generated vorticity with opposite-sign tail-generated vorticity, resulting in the formation of a weak thrust wake. en
dc.format.extent 912515 bytes
dc.format.mimetype application/pdf
dc.language.iso en_US en
dc.publisher Cambridge University Press en
dc.rights Copyright: Cambridge University Press This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.
dc.subject flow structures en
dc.subject vorticity control en
dc.subject fish-like en
dc.title Three-dimensional flow structures and vorticity control in fish-like swimming en
dc.type Article en
dc.identifier.citation Journal of Fluid Mechanics, 468, p.1-28 (2002) en

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