Fluid-Solid-Electric Lock-In of Energy-Harvesting Piezoelectric Flags

Sustainable energy sources surround us, but we must harness them. The periodic, self-sustained deformation of a piezoelectric flag as it flaps in a fluid flow, for example, could be used to convert mechanical energy from wind, or a river or ocean current, into electrical power. The authors show that the interaction between fluid forcing, flapping dynamics, and the resonant properties of the output circuit can lead to a lock-in mechanism that significantly enhances flapping, energy transfer, and efficiency.