Bluff body design for vortex-induced vibration energy harvesting

This research utilizes Computational Fluid Dynamics (CFD) and Finite Element Method (FEM) to investigate the Fluid-Structure Interaction (FSI) problem of a Vortex-Induced Vibration (VIV) energy harvesting device from water flow. The aim of this work is to compare various bluff body shapes and determine the shape that offers high performance for energy harvesting. The shape models are generated using SolidWorks and then simulated using Altair HyperWorks (SimLab, AcuSolve, and OptiStruct). Water flows around bluff bodies at a free stream velocity of 1 m/s, with Reynolds number 35,000, causing vortex formation and flexible beam vibration behind. A frontal or projected area of bluff body is applied to all shapes with 35 and 30 mm in height and width, respectively. The streamwise length is 30 mm, which is equivalent to the diameter of the cylinder, and the flexible beam length is 1.2 times the streamwise length. The monitoring parameters are the displacement of the beam, the drag coefficient (CD), the lift coefficient (CL), and the Strouhal number (St). Furthermore, velocity, pressure and vorticity contours are investigated. The simulation results have shown that the MGX-1 shape (magnet with sharp ends) has the highest equivalent power and beam displacement improvement, with values of 134.93% and 77.55% compared to the circular cylinder shape. The vorticity and pressure contours explain the physical phenomena, where the high vortex intensity region creates a significant pressure difference at the flexible beam, resulting in higher beam displacement.