Hydrodynamic performance of manta rays under different motion parameter

Abstract

Abstract This paper presents a numerical simulation of the steady propulsion state of manta rays and investigates the influence of single motion parameters and the addition of perturbation signals on the hydrodynamic characteristics and vortex evolution of manta rays. A numerical model and the motion equations of the manta ray were established by observing the living organisms, and then a computational method combining the immersed boundary method (IBM) and the Sphere function-based Gas Kinetic Scheme (SGKS) was used to simulate the active propulsion state of the manta ray. The results show that in a single motion parameter, as the motion frequency increases, the thrust force increases subsequently, but the propulsion efficiency decreases; with the increase of motion amplitude, the thrust also increases, and the propulsion efficiency reaches the maximum at the dimensionless amplitude of 0.35; as the wavenumber increases, the thrust reaches its maximum at wavenumber of 0.4, and the propulsion efficiency increases subsequently. When the same amplitude low-frequency sinusoidal perturbation is added, both thrust and efficiency decrease when the perturbation frequency is less than or equal to 0.4, and increase when the perturbation frequency is greater than 0.6. This work provides a new perspective to study the influence of manta ray motion parameters and perturbation parameters on its hydrodynamic characteristics.