Fluid mechanical consideration on tunas' finlet

Abstract

In late years a function and the structure of the creature called biomimetics are applied to technical development. We focused on the tuna that could swim in the water at high speed. A saw-like fin is between the tail and fins from the 2nd dorsal fin in fish like tuna. A fin of the triangle is called finlets, and there is in the back and ventral. It is thought that the finlets brings the effect that the flow behind the fish rectifies at present. Its role was inspected experimentally by the fluid force sensing using a made model. The experimental result by the fluid force measurement was not seen in the variation of the flow with or without finlets. The one when equipping finlets more than the time of non-equipment, indicated a higher C_D.