Numerical simulation of energy harvesting eel in a viscous flow

Abstract

Inspired by the energy harvesting eel, a flexible flag behind a D-shape half cylinder in a uniform viscous flow was simulated by using the immersed boundary method. The downstream flag was strongly influenced by the vortices shed from the upstream cylinder in vortex-vortex and vortex-body interactions. The flexible flag was subjected to passive flapping to optimize the geometric and the flow parameters, which were subsequently used in the actively flapping flag. In this study the dependence of the bending energy of the passively flapping flexible flag was examined in detail for multiple parameters, these optimized parameters were used in the active flapping motion to investigate the effect of the phase difference, the amplitude of the pitching and heaving motion. The maximum bending energy was observed for the range of the phase difference and the amplitudes. Constructive and destructive vortex interaction modes, unidirectional and bidirectional bending and the different flapping frequency were found which explained the variations in the bending energy on the downstream flag.