A Biologically Inspired Computational Study of Flow Past Tandem Flapping Foils

Numerical simulations have been used to analyze the effect that vortices, shed from one flapping foil, have on the thrust of another flapping foil placed directly downstream. The simulations attempt to model the dorsal-tail fin interaction observed in a live bluegill sunfish by Drucker & Lauder using Particle Image Velocimetry (PIV). The simulations have been carried out using a Cartesian grid method that allows us to simulate flows with complex moving boundaries on stationary Cartesian grids. The simulations indicate that vortex shedding from the upstream dorsal fin is indeed capable of increasing the thrust of the tail fin significantly. However, this thrust augmentation is found to be quite sensitive to the phase relationship between the two flapping fins. The numerical simulations allows us to examine the underlying physical mechanism for this thrust augmentation.