Hydrodynamic characterization of manta rays in bowed gliding state

To investigate the hydrodynamic performance of manta rays under bowed gliding conditions, a computational model of manta rays under different bowed angles was first established based on biological observations, and manta ray gliding propulsion under different combinations of bowed angles and angles of attack was numerically simulated based on the immersed boundary method. The results showed that upward deformation of the pectoral fins helped to improve the lateral change in pectoral fin posterior streamlines, thus effectively reducing the gliding drag. The larger the deformation was, the greater the drag reduction, with a maximum drag reduction of 24.71%. Slight upward deformation increased the lift, but this caused increased upward deformation and decreased lift, while bowed gliding provided manta rays with a higher lift-to-drag ratio.