Control of vortex-induced vibration of an elastically mounted cylinder with a pair of porous rods

Abstract

In this work, the control of vortex-induced vibration (VIV) of an elastically mounted cylinder with a pair of porous rods is numerically investigated at a Reynolds number of 150. To calculate the forces on the moving porous media, an efficient formula based on the momentum theorem is proposed. The porous rods are placed behind the cylinder at an angle of 25°, and the effects of the gap ratio (G) and permeability of the porous rods (Da) on the VIV are studied in detail. Based on the results obtained, it is found that at small G, the VIV is suppressed mainly through the action of shear-layer separation and reattachment. In addition, better performance of VIV control can be achieved by using porous rods with lower Da. As G increases, the porous rods maintain good performance, while solid rods enhance the vibration, the latter being caused by the interaction between the vortices shed from the main cylinder and the rods. The best control effect is achieved by using porous rods at Da = 0.0001 and G = 0.7. The corresponding reductions of vibration amplitude, drag force, and lift force are 85%, 33%, and 84%, respectively.