Numerical investigation of wake and flow-induced vibrations of a rotating cylinder in flow

Abstract

The flow-induced vibrations of a two-degrees-of-freedom rotating cylinder with rotation rates between 0 and 3, reduced velocities from 1 to 12, a Reynolds number of 200 and a mass ratio of 2.6 are investigated by numerical simulations. Seven wake patterns (2S, P + S, T + S, P + T, 2P, 2T, and U) are captured, and relevant regions are confirmed. With the increase in the rotation rate and the reduced velocity, the vortex structure varies from the 2S pattern to the P + S, T + S, P + T and 2P patterns and, finally, to the 2T pattern. The cross-flow amplitude is weakened for 0≤α≤1 and shows multiple jumps for 2≤α≤3, and the amplitude reaches a higher peak in every jump. With the increase in the rotation rate, the cylindrical trajectory varies from narrow elliptical-like to circular-like and finally to flat elliptical-like. The wake transition from the 2S pattern to the multiple-vortex pattern undergoes four phases (U/2S--P + S--T + S/P + T/2P--2T), and every wake pattern transition is accompanied by a jump in hydrodynamics and amplitudes.