Effect of Manta Ray's Flexible Hydrofoil Kinematic Parameters on Autonomous Propulsion Efficiency

Marine organisms have evolved various locomotion methods over millions of years to adapt to aquatic environments. Manta rays, with their pectoral fins and flexible hydrofoil propulsion, inspire advancements in underwater propulsion systems. In this study, an overlapping grid was used to create a simplified model based on the pectoral fins of a manta ray. The oscillatory traveling wave equation is programmed and loaded on the pectoral fin model to characterize the motion state of the manta ray cross-section. It explored how wavelength and frequency affect the efficiency of flexible hydrofoil swimming. Results showed that flexible hydrofoils create reverse Kármán vortex streets during autonomous swimming. The size of these vortices, along with frequency and wavelength, impacts propulsive efficiency. When frequency is fixed, increasing wavelength increases turbulence, reducing efficiency but slightly boosting speed. Conversely, fixing wavelength and increasing frequency improves stability, enhancing efficiency and speed. This research offers new insights for designing biomimetic underwater propulsion systems in marine engineering.