Vortex-Induced Vibrations Based Energy Harvester: Reduced-Order Modeling, System Dynamics, and Performance

Oscillations of a bluff body comprised of a cylinder attached with a piezoelastic cantilever are considered in this work. An extended reduced-order model is presented for studying the dynamics and energy harvesting performance of the piezoelastic cantilever excited by vortex-induced vibrations shed from a circular cylinder at the cantilever's free end. The overall system model is constructed by integrating a classical wake oscillator model for the vortex-induced vibrations with a finite-element formulation for the piezoelastic cantilever. Apart from the reduced-order model's use for analysis of system dynamics and stability, this model is intended for predicting the electrical output resulting from the piezoelectric transduction. For different bluff-body parameters, model predictions are made and compared with previously published experimental data obtained independently in three different studies. Furthermore, system instabilities and bifurcations with respect to control parameters such as the mass ratio have been examined. From the comparisons of the obtained model predictions with published experimental data, it is inferred that the reduced-order model can be used to capture the key aspects of the vortex-induced vibrations, such as the lock-in region, oscillation frequency inside and outside this region, and maximum response amplitude inside the lock-in region. In addition, the model can also be used to determine the harvested electrical power, suggesting the use of the model for performance analysis of bluff-body energy harvesters.