Vortex-induced vibrations of two degrees-of-freedom sprung cylinder with a rotational nonlinear energy sink: A numerical investigation

Vortex-induced vibration (VIV) is a common fluid-structure interaction phenomenon in the field of wind engineering and marine engineering. The large-amplitude VIV has a marked impact on the slender structure in fluids, at times even destructive. To study how the VIV can be controlled, the dynamics of a rigid cylinder attached to a rotational nonlinear energy sink (R-NES) is investigated in this paper. This is done using a two degrees-of-freedom (2DOF) Van der Pol wake oscillator model adapted to consider a coupled vibration in cross-flow and streamwise directions. The governing equation of R-NES is coupled to the wake oscillator model; hence, a flow-cylinder-NES coupled system is established. While exploring the dynamics of the cylinders with different mass ratios under the action of R-NES, it was found that the R-NES delivers better performance in suppressing the VIV of a cylinder with high mass ratios than that of a low mass ratios cylinder. The effect of the distinct parameters of R-NES on VIV response was also systematically investigated in this study. The results indicate that higher mass parameter β and rotation radius r can lead to improved performance, while the effect of the damping parameter ξ is complex and appears to be linked to the mass ratio of the column structure.