Thrust production and wake structure of a batoid-inspired oscillating fin
Experiments are reported on the hydrodynamic performance of a flexible fin. The fin replicates some features of the pectoral fin of a batoid fish (such as a ray or skate) in that it is actuated in a travelling wave motion, with the amplitude of the motion increasing linearly along the span from root to tip. Thrust is found to increase with non-dimensional frequency, and an optimal oscillatory gait is identified. Power consumption measurements lead to the computation of propulsive efficiency, and an optimal efficiency condition is evaluated. Wake visualizations are presented, and a vortex model of the wake near zero net thrust is suggested. Strouhal number effects on the wake topology are also illustrated.(Published Online August 14 2006)
(Received August 19 2005)
(Revised February 13 2006)
p1 Present address: Lockheed Martin Maritime Systems and Sensors, 17th St East Riviera Beach, FL 33404, USA.