Hydrodynamic loads and vortex evolution from a flapping fin near a solid body

The pectoral fins of fish play an important role in the fine control of fish motion. The dynamics of a simplified fin-body configuration is examined in experiments to study the hydrodynamic loads and the vortex dynamics of fin-body interactions under selected actuation inputs. The loads show different mean values, amplitudes, and hysteresis depending on the mean fin angle and the flapping frequency. Particle image velocimetry results reveal the influence of the shear layer and the fin-tip vortex on the hydrodynamic loads. Preliminary analysis of the quantitative contributions from the vortical, viscous, and inviscid flow effects is performed using the force/moment partitioning method.