On the Effects of the Peduncle Depth, Caudal Fin Shape and Dorsal Fin Position on the Cruising Performance of a Free-Swimming Fish Mode

To better understand the correlation between fish morphology and its cruising performance, this study simulated swimming fish models with varying peduncle depths, caudal fin shapes and dorsal fin positions, analysed their hydrodynamics and compared their swimming performance. The results showed that varying the peduncle depths and/or the caudal fin shapes trades off between acceleration, cruising speed and efficiency, while varying the position of the dorsal fin affects the dorsal fin thrust, the interaction between the dorsal fin's wake and the caudal fin, and the augmentation of the thrust on the caudal fin from the fin-wake interaction. These observations explained the association of the morphological preference of natural fish with their required swimming performance. To complement the study, a formula that is applicable to the laminar and turbulent flow regime was derived from the Large-Amplitude Elongate-Body Theory to estimate the swimming speed of a swimmer from its kinematics.