Effects of a square bump on hydroenergy harvesting of a cylinder undergoing flow-induced vibrations

In this study, 2-dimensional (2D) numerical simulations in two-degree-of-freedom are performed to explore the vibration response and available power characteristics of an elastically-supported circular cylinder with a single square bump on its surface as the passive turbulence control (PTC) method. The bump is mounted at 5 different angles (alpha = 0 degrees, 45 degrees, 90 degrees, 135 degrees, 180 degrees) from the leading edge on the cylinder surface. As compared to the bare cylinder, the dynamic response and output power of the bumped cylinder are enhanced evidently, especially for alpha = 45 degrees, 90 degrees and 135 degrees due to the asymmetric structure leading to the coupling between vortex-induced vibration (VIV) and galloping. For alpha = 90 degrees, the bumped cylinder could achieve a maximum harnessed power of 2.76 mW, representing a remarkable improvement of 393% than the bare cylinder. The vortex-shedding patterns are described in detail to reveal the underlying fluid-structure interaction mechanism.