Numerical and experimental analysis for influence of the caudal fin shape on the propulsion performance

This paper presents a comprehensive study on the effects of the caudal fin shape on the propulsion performance of a harmonically heaving and pitching caudal fin. A simulation program based on an unsteady panel method was developed to analysis the hydrodynamic performance of a flapping caudal fin for three shapes (the whale caudal fin, the dolphin caudal fin, and the tuna caudal fin). Then, a series of hydrodynamic experiments for three caudal fin shapes were performed. Both computational and experimental results indicate that the tuna caudal fin produces the highest efficiency. However the mean thrust coefficient of the tuna caudal fin is the smallest. It is found that although the mean thrust coefficient for the tuna caudal fin is not large, input power of the tuna caudal fin is also quite small. So the tuna caudal fin achieves a high efficiency.