Flexible Flapping Dynamics of Parallel Elastic Plates in a Uniform Flow: Application to Energy Harvesting Devices

A new high-order finite element Coupled Field with Explicit Interface (CFEI) code has been developed for simulating flapping motion of a thin flexible body in a uniform flow with strong add-mass effects. In the first part, we study the flapping dynamics of a single cantilevered plate for wide range of mass ratios and maintaining relatively low bending rigidity through our direct fluid-structure simulations. As a function of mass-ratio, the flapping dynamics reveals three distinct regimes: (i) fixed-point stable; (ii) limit-cycle flapping; and (iii) chaotic flapping. The changes associated with regime transition with increasing mass ratio are analyzed by vortex wake patterns and tip-displacement responses. Dependencies of stability predicted by the theoretical analysis are confirmed by the nonlinear fluid-structure simulations. In the second part, two parallel cantilevered plates will be investigated as a function of spacing between the parallel plates to assess the flapping motion and the net energy transfer. The flow-induced vibrations of this kind of coupled system have a potential to extract energy from the surrounding fluid flow for generation of electric power.Copyright © 2014 by ASME