Flow-induced vibration of an inelastic cylinder in wake

Abstract: Previous studies have shown that an elastic cylinder positioned in the wake of a rigid cylinder undergoes wake-induced galloping vibration. However, there has been minimal focus on investigating the vibration of a plunging (zero-stiffness) cylinder in a similar flow configuration. A systematic study is conducted on the wake-induced vibration of a plunging or zero structural-stiffness cylinder placed behind a rigid cylinder. The mass ratio of the plunging cylinder is 11.1. The plunging cylinder in the wake becomes aerodynamically elastic due to the flow-induced stiffness generated. The concerned aeroelastic natural frequency of the cylinder is smaller than the vortex shedding frequency regardless of the Reynolds number and the spacing between the cylinders. Galloping vibrations following the desynchronization branch are thus generated in the Re range examined. The quiescent fluid added mass, damping, and flow-induced stiffness all play a role in determining the aeroelastic natural frequency of the cylinder. The flow-induced stiffness has a linear relationship with Re, differing between the reattachment and coshedding flow regimes as well as between the desynchronization and galloping branches. The flow-induced stiffness is generally higher in the reattachment regime than in the coshedding regime. The cylinder undergoes a smaller stiffness in the galloping branch than in the desynchronization branch. Keywords: Wake-induced stiffness, Flow-induced vibration, Inelastic cylinder, Tandem cylinders