Research on the Hydrodynamic Performance of Manta Rays Using a 2D CFD Model

Currently, the most commonly used method to study the hydrodynamic performance of manta rays is computational fluid dynamics (CFD) simulation. In this research, we investigated the effects of kinematic parameters—specifically wave number, amplitude, and frequency—on the hydrodynamic performance of manta rays during the swimming process by constructing a 2D CFD model. First, we verified the reasonableness of the 2D simulation. Subsequently, a 2D simulation was used to study the hydrodynamic performance of manta ray pectoral fins, and it was concluded that using low-amplitude, high-frequency propulsion with an optimal wave number has better energy utilization. Finally, we conducted orthogonal experiments, which revealed that the thrust reaches a maximum value of 8.55 N at a frequency of 1 Hz, amplitude of 0.3 c, and wave number of 0.4, and the quasi-propulsive efficiency reaches a maximum value of 82.4% at a frequency of 0.8 Hz, amplitude of 0.3 c, and wave number of 0.4. In general, we can regulate the wave number to a range of 0.35 to 0.4, the frequency to between 0.7 and 0.9 Hz, and the amplitude to between 0.3 c and 0.325 c. This configuration yields a thrust exceeding 3.04 N and a quasi-propulsive efficiency surpassing 70.4%.