Vortex-induced vibration of a linearly sprung cylinder with an internal rotational nonlinear energy sink in turbulent flow

We computationally investigate flow past a three-dimensional linearly sprung cylinder undergoing vortex-induced vibration (VIV) transverse to the free stream and equipped with an internal dissipative rotational nonlinear energy sink (NES). The rotational NES consists of a line mass allowed to rotate at constant radius about the cylinder axis, with linearly damped rotational motion. We consider a value of the Reynolds number (Re = 10,000, based on the cylinder diameter and free-stream velocity) at which flow past a linearly sprung cylinder with no NES is three-dimensional and fully turbulent. For this Re value, we show that the rotational NES is capable of passively harnessing a substantial amount of kinetic energy from the rectilinear motion of the cylinder, leading to a significant suppression of cylinder oscillation and a nearly twofold reduction in drag. The results presented herein are of practical significance since they demonstrate a novel passive mechanism for VIV suppression and drag reduction in a high-Re bluff body flow, and lay down the ground-work for designing nonlinear energy sinks with a view to enhancing the performance of VIV-induced power generation in marine currents.