Experimental study of the distribution of drag coefficients in water generated by streamlined bodies*

Fish have a mechanism for gaining momentum through various motions to move underwater. Tail movements with more than 3 Hz are necessary for rapid propulsion. However, other methods of reducing drag are also required. In this study, we investigated the drag coefficient of a fish's body. The study used a reduced scale model with dimensionless coefficients at a maximum flow velocity of 1.0 m/s or less using a circulating water channel. The distribution of the drag coefficient was determined as a function of the scale model's yaw angle and periodic rotational motion. In the future, we plan to utilize these results to design self-powered unmanned underwater robots.