Numerical simulation on the propulsion performance of a bioinspired swimmer with crescent-shaped caudal fin during accelerating and cruising motion

Evolutionary pressure has produced fish with excellent propulsion performance. In particular, most fish species with a high cruising speed have a crescent-shaped caudal fin. The present study focused on the role of the caudal fin shape on the swimming stability of fish models. Four fish models with different vertical and horizontal projections for the caudal fin shape were constructed, and numerical simulations were performed to investigate the hydrodynamic performance in the accelerating and cruising modes. The results indicated that different tip curvatures for the caudal fin plays a major role on the hydrodynamic performance and vortex structure of the fish model. And the propulsion performance was improved by using caudal fins with suitable thickness. Meanwhile, the lateral stability of the fish model was mainly affected by the undulating angle of caudal fin.