Analysis of flow induced by fins oscillating near the water surface

Aquatic organisms that swim at high speeds, such as dolphins and tuna, use a propulsion method called lift propulsion, the mechanism of which has been the subject of much research. The propulsive force generated by the tail fins of aquatic organisms is extremely strong and has attracted much attention in biomimetic technology, especially in the study of fish-shaped robots. However, even though aquatic organisms swim near the water surface when feeding, few studies have focused on swimming near the water surface. We found that propulsive force increases when the frequency of water surface waves and fins are synchronized, and that turbulence of water surface waves attenuates propulsive force.