An experimental investigation into the stride lengths and wakes of bio-inspired fins with parametrically varied planform geometries and oscillatory kinematics

The caudal fins and flukes of swimming animals may exhibit significant diversity among species in terms of planform, leading edge shape, and trailing edge shape. The current work uses experiments to investigate the self-propelled swimming speeds and stride lengths of bio-inspired pitching and heaving propulsors of varying planform shape in a recirculating water channel. Trailing and leading edge shape, as well as oscillatory kinematics, are varied for a series of bio-inspired panels with a nominally trapezoidal planform. Thirteen panel geometries were parametrically varied to facilitate investigations into specific geometric factors and their influence on swimming performance. Time-varying results obtained from particle image velocimetry at the midspan plan illustrate what wake features and behaviors are associated with optimal swimming performance and changes in oscillatory kinematics. The analysis of swimming performance and wake behaviors is discussed in the context of changes to planform shape, aspect ratio, and kinematics. The findings of the current work have implications on our understanding of the propulsor shapes found in swimming animals and also on the design of bio-inspired vehicles during conditions of constant velocity swimming.