Etching metasurfaces on bluff bodies for vortex-induced vibration energy harvesting

Abstract

Bluff bodies play crucial roles in affecting the functionality of wind energy harvesting systems. Inspired by the versatility and wide application of metasurfaces in many fields, we propose to etch several metasurface patterns on a cylinder bluff body and investigate their effects on vortex-induced vibration (VIV). A general lumped parameter model is developed for VIV piezoelectric energy harvesters (VIVPEHs). Three-dimensional CFD simulation models are built to obtain the lift and drag coefficients. Wind tunnel tests are conducted to experimentally study the dynamics and evaluate the voltage output. The theoretical results matched well with the experimental ones. It is unveiled that etching the concave metasurface patterns on the bluff bodies has a significant influence on the dynamic behavior of the bluff body, thus enhancing or suppressing VIV. Beside, we demonstrate the influences of the etched metasurface patterns on the generated vortex street behind the bluff bodies through CFD simulations. It is shown that different concave metasurface patterns could significantly affect the wake pressure, thus influencing the aerodynamics. Furthermore, the effects of the electrical parameters, including the load resistance and electromechanical coupling strength, on energy harvesting performance are investigated based on the theoretical model.