Fluid Engineering Laboratory
Department of Mechanical Engineering
Meiji University



Stereo PIV study of flow around a live swimming fish

Sakakibara, J., Nakagawa, M., Yoshida, M., 2004, "Stereo-PIV study of flow around a maneuvering fish", Experiments in Fluids, Vol.36, pp.282-293. (PDF)

Flow around a live fish in turning motion has been experimentally investigated using stereo-PIV. A gold fish, 90mm in length, was released in a rectangular Plexiglas tank (200mm x 800mm) in horizontal cross-section, 200mm depth of water) with tracer particles ( 50 micron in diameter), and a laser light sheet illuminating vertical (horizontal) plane visualized a flow behind (around) the fish. Two of CCD cameras captured the particle images, and the other two of CCD cameras captured the fish's body to reconstruct quasi 3D volumetric shape of the fish. The fish, in turning motion, bends its body quickly to change the direction of the head, and then sweeps the tail. Two jets were formed near the tail; one is perpendicular to the body axis which produces thrust to rotate the body, and the other is for backward to swim straight forward after the turn. The vertical slice of the velocity field shows those jets having approximately same length scale as height of the tail.



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Three-components velocity in a vertical plane behind a fish in turning motion measured by stereo-PIV; vectors:in-plane, color contours:out of plane component. Three-dimensional fish shape, represented by green surface, was measured at same time.



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Three-components velocity in a horizontal plane around a fish in turning motion measured by stereo-PIV; vectors:in-plane, color contours:out of plane component. Three-dimensional fish shape, represented by green surface, was measured at same time.



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Three-components velocity in a horizontal plane around a fish in rising motion measured by stereo-PIV; vectors:in-plane, color contours:out of plane component. Three-dimensional fish shape, represented by green surface, was measured at same time.



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Two-dimensional velocity around a fish in turning motion measured by PIV.

Schematic of three-component velocity and shape measurement around a fish. CCD1 and CCD2 capture PIV images in the light sheet plane. CCD3 and CCD4 capture the shadows of the fish, then common volume of those projections are identified as the fish body.



A snap shot of an experiments on measureing flow behind a fish by stereo-PIV