Investigation of the Hydrodynamic Characteristics of Two Manta Rays Tandem Gliding

Abstract

Collective motion is a unique biological habit of manta rays. As the most basic unit, the hydrodynamic mechanism of tandem gliding deserves further study. In this paper, a numerical simulation method was used to explore the influence of the front-to-back distance and the angle of attack on the overall and individual hydrodynamic performance of a pair of manta rays gliding. Specifically, a numerical simulation of the hydrodynamic parameters and the distribution of pressure and velocity fields was carried out when the pair of manta rays were arranged at a distance of 0.25–1 times the body length and the angle of attack was −8° to 8°. The simulation results show that, when a pair of manta rays glide at close range, compared to a single manta ray gliding, the resistance of the leader is greatly reduced, and the lift changes little, while the resistance of the follower is greatly increased, and the lift is significantly reduced. For the average resistance of the system, in the specific scenario of a close range and a small negative degree angle of attack, the two manta rays’ tandem gliding system can significantly reduce the resistance and play a role in reducing resistance and saving energy. The research content of this paper provides a theoretical basis for understanding the biological habits of manta rays and designing an underwater bionic robot group system.