Study of Boxfish Propulsion with Rigid Caudal Fins

The ostraciiform swimming mode is a simple propulsion mechanism for underwater vehicles. Both the swimming velocity and turning rate can be controlled by the flapping of caudal fin. In this research, the thrusting characteristics of an ostraciiform robotic fish were studied with some experiments. The drag coefficient and added mass of the boxfish were also determined experimentally. Both the flapping frequency and amplitude were varied to explore their effects on the terminal velocity. The experimental data were compared with some theoretical calculations.