Suppression of the Vortex-Induced Vibration of a Circular Cylinder with Low Mass Damping

Numerical simulations are carried out to investigate the aerodynamic coefficients of a stationary circular cylinder with bypass channels and its vortex-induced vibration (VIV) under low mass-damping conditions. A progressive increase in the bypass channel thickness (T) from 0.05D to 0.40D (where D is the cylinder diameter) leads to a notable reduction in both the root-mean-square lift (Clrms) and mean drag (Cdmean) coefficients. The optimal suppression occurs at T=0.4D in our simulations, where Clrms is reduced by 99.5% and Cdmean by 60.7% compared to that of the bare cylinder. Proper orthogonal decomposition of the fluctuating velocity field reveals that the bypass channels transform the antisymmetric alternating vortex shedding in the wake into the symmetric patterns, which is responsible for the alleviation of Clrms. Simultaneously, the flow blowing from the bypass channels inhibits the formation of strong large-scale vortices in the wake. As a result, the energy dissipation in the wake is reduced, contributing to increased base pressure and a consequent attenuation of Cdmean. Finally, the two-degree-of-freedom vibration simulations of a spring-mounted cylinder confirm that the bypass channels nearly eliminate the VIV of the cylinder in low mass-damping configurations.