Numerical investigation of cylinder vortex-induced vibration with downstream plate for vibration suppression and energy harvesting

The effect of the downstream plate on the vortex-induced vibration (VIV) of the cylinder is numerically studied for the first time by using the fluid-structure interaction method. The influences of the plate height (H) and the gap length (G) between the plate and the cylinder on the cylinder dynamic characteristics are investigated. The main conclusions can be summarized as follows: (1) Cylinder will first be converted from VIV to galloping and then reverted to the classical VIV response with the increasing gap length and the plate height. (2) Under the plate interference, the switch of the wake vortex shedding mode from "2S" to "P + S & DPRIME;, the increase in lift odd harmonic components and amplitude, and the decrease of the phase difference between lift and displacement are the essential reasons for the enhanced vibration. (3) In the optimal galloping state (G = 0.5 D, H = 0.5 D), the cylinder amplitude and lock-in range are increased by 670.8% and 473% compared to that of the isolated cylinder system, respectively, which is beneficial to energy harvesting. (4) The reattachment flow appearance and cylinder wake vortex-shedding suppression induced by the high plate, are the deep reasons for the vibration weakening. In this case, the lift force and vortex-shedding frequency are greatly reduced, while the lock-in interval is delayed or even eliminated. (5) When H = 3.0 D and G = 0.5 D, the lock-in interval is 100% cleared, and the vibration intensity of the cylinder is reduced by 84.4%. (6) The feasibility of utilizing the square plate for flow-induced vibration control of non-cylindrical bluff bodies is verified for the first time. Overall, the above results are of great significance for optimizing structural vibration control and vortex sensing technology based on VIV suppression, as well as energy harvesting aiming at enhancing vibration.