Vorticity Dynamics and Control of the Three Dimensional Self-propelled Travelling Wave Wall in Ground Effect

Undulatory rays, propelled by the enlarged pectoral fin on both sides of body, swim close to the substrate. The pectoral fins undulate in the form of a three-dimensional traveling wave. However, the physical mechanisms of the 3D traveling wave in ground effect are especially unknown. The self-propelled locomotion of the 3D traveling wave wall in ground effect is investigated in this study, with a 3D computational fluid dynamics package that combines the immersed boundary method, the volume of fluid method, the adaptive multi-grid finite volume method, and the control strategy of swimming. The influences of ground effect on the locomotion of the 3D traveling wave wall are analyzed. The fluid mechanisms of swimming of the 3D traveling wave wall in ground effect are revealed using vorticity dynamics. From numerical simulations and vorticity dynamics, it is found that the 3D traveling wave wall can achieve high swimming performance on the bottom of water through flow control.