Interdisciplinary Seminar in Nonlinear Science

Title: How fishes swim: experimental hydrodynamics and the mechanics of flexible propulsors
Speaker: George Lauder
Speaker Info: Harvard University
Brief Description:
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There are 25,000 species of fishes, and a key feature of this remarkable evolutionary diversity is a great variety of propulsive systems used by fishes for maneuvering in the aquatic environment. Fishes have numerous control surfaces (fins) which act to transfer momentum to the surrounding fluid. Fishes are unstable and use several control surfaces simultaneously for propulsion and to maintain body position. In this presentation I will discuss the results of recent experimental kinematic and hydrodynamic studies of fish fin function. Recent high- resolution video analyses of fish fin movements during locomotion show that fins undergo much greater deformations than previously suspected. Experimental work on fin mechanics shows that fishes possess a mechanism for actively adjusting fin surface curvature to modulate locomotor force. Fish fin motion results in the formation of vortex rings of various conformations, and quantification of vortex rings shed into the wake by freely-swimming fishes has proven to be useful for understanding the mechanisms of propulsion. Experimental study of fish propulsion in combination with computational fluid dynamic analysis is providing the basis for the design of biomimetic robotic fin-thrusters for use in low- speed maneuvering underwater vehicles.
Date: Friday, November 04, 2005
Time: 2:00PM
Where: Tech M416
Contact Person: Malcolm MacIver
Contact email: maciver@northwestern.edu
Contact Phone: 847-491-3540
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