QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Figures Only Full Text Full Text (PDF) Movies Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Liao, J. C. Articles by Triantafyllou, M. S. Search for Related Content PubMed PubMed Citation Articles by Liao, J. C. Articles by Triantafyllou, M. S. Social Bookmarking                         What's this?

The Journal of Experimental Biology 206, 1059-1073 (2003)
doi: 10.1242/jeb.00209

The Kármán gait: novel body kinematics of rainbow trout swimming in a vortex street

James C. Liao^1,*, David N. Beal², George V. Lauder³ and Michael S. Triantafyllou⁴

¹ Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
² Department of Ocean Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
³ Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
⁴ Department of Ocean Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA

^* Author for correspondence (e-mail: jliao{at}oeb.harvard.edu)

Accepted 23 December 2002

Most fishes commonly experience unsteady flows and hydrodynamic perturbations during their lifetime. In this study, we provide evidence that rainbow trout Oncorhynchus mykiss voluntarily alter their body kinematics when interacting with vortices present in the environment that are not self-generated. To demonstrate this, we measured axial swimming kinematics in response to changes in known hydrodynamic wake characteristics. We compared trout swimming in the Kármán street behind different diameter cylinders (2.5 and 5 cm) at two flow speeds (2.5 and 4.5 L s^-1, where L is total body length) to trout swimming in the free stream and in the cylinder bow wake. Trout swimming behind cylinders adopt a distinctive, previously undescribed pattern of movement in order to hold station, which we term the Kármán gait. During this gait, body amplitudes and curvatures are much larger than those of trout swimming at an equivalent flow velocity in the absence of a cylinder. Tail-beat frequency is not only lower than might be expected for a trout swimming in the reduced flow behind a cylinder, but also matches the vortex shedding frequency of the cylinder. Therefore, in addition to choosing to be in the slower flow velocity offered behind a cylinder (drafting), trout are also altering their body kinematics to synchronize with the shed vortices (tuning), using a mechanism that may not involve propulsive locomotion. This behavior is most distinctive when cylinder diameter is large relative to fish length. While tuning, trout have a longer body wavelength than the prescribed wake wavelength, indicating that only certain regions of the body may need to be oriented in a consistent manner to the oncoming vortices. Our results suggest that fish can capture energy from vortices generated by the environment to maintain station in downstream flow. Interestingly, trout swimming in front of a cylinder display lower tail-beat amplitudes and body wave speeds than trout subjected to any of the other treatments, implying that the bow wake may be the most energetically favorable region for a fish to hold station near a cylinder.

Key words: Kármán street, vortex street, drag wake, vortex, cylinder, hydrodynamic perturbation, swimming kinematics, rainbow trout, Oncorhynchus mykiss, Kármán gait, drafting, tuning, tacking, entraining

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				S. M. Swartz, K. S. Breuer, and D. J. Willis Aeromechanics in aeroecology: flight biology in the aerosphere Integr. Comp. Biol., July 1, 2008; 48(1): 85 - 98. [Abstract] [Full Text] [PDF]

				U. K. Muller, J. G. M. van den Boogaart, and J. L. van Leeuwen Flow patterns of larval fish: undulatory swimming in the intermediate flow regime J. Exp. Biol., January 15, 2008; 211(2): 196 - 205. [Abstract] [Full Text] [PDF]

				J. Peng and J. O. Dabiri An overview of a Lagrangian method for analysis of animal wake dynamics J. Exp. Biol., January 15, 2008; 211(2): 280 - 287. [Abstract] [Full Text] [PDF]

				J. C Liao A review of fish swimming mechanics and behaviour in altered flows Phil Trans R Soc B, November 29, 2007; 362(1487): 1973 - 1993. [Abstract] [Full Text] [PDF]

				J. C. Liao The role of the lateral line and vision on body kinematics and hydrodynamic preference of rainbow trout in turbulent flow J. Exp. Biol., October 15, 2006; 209(20): 4077 - 4090. [Abstract] [Full Text] [PDF]

				E. G. Drucker and G. V. Lauder Locomotor function of the dorsal fin in rainbow trout: kinematic patterns and hydrodynamic forces J. Exp. Biol., December 1, 2005; 208(23): 4479 - 4494. [Abstract] [Full Text] [PDF]

				J. C. Liao Neuromuscular control of trout swimming in a vortex street: implications for energy economy during the Karman gait J. Exp. Biol., September 15, 2004; 207(20): 3495 - 3506. [Abstract] [Full Text] [PDF]

				J. C. Liao, D. N. Beal, G. V. Lauder, and M. S. Triantafyllou Fish Exploiting Vortices Decrease Muscle Activity Science, November 28, 2003; 302(5650): 1566 - 1569. [Abstract] [Full Text] [PDF]