Meeting Abstract
Flexion in flapping fins is a hallmark of fish swimming. It’s widely thought that this flexion may be the source of fish’s efficient swimming. However, there is a lack of literatures on studying the fin flexion and its hydrodynamic role of swimming rays. In this work, a combined experimental and computational study of a swimming manta ray is being conducted. High resolution videos of forward swimming manta rays are obtained and used as a basis for developing high fidelity geometrical models of the ray body and fins. A 3D image-based surface reconstruction method is then used to obtain the kinematics and flexibility of ray fins. The observed fin flexion is highly complex and a number of different strategies including singular vector decomposition (SVD) of the fin kinematics are used to examine the various kinematical features and their impact on the fin performance. Immersed boundary method based CFD simulations are carried out to examine the hydrodynamic performance of fin flexion involving different kinematical features and understand the corresponding wake structures. A cownose ray is also used to compare the variety of the fin flexion in a similar swimming motion. Results have shown that the bending angle and bending rate of the fin tip play important roles in rays’ fin propulsion.
