Two-degree-of-freedom flow-induced vibration of a rotating circular cylinder

Abstract The flow-induced vibration (FIV) of a rotating circular cylinder in reduced velocity range of 3.0 ≤ U*≤14 is investigated numerically. The forced rotating cylinder can freely vibrate in flow and cross flow directions. The amplitude and frequency are analyzed to understand the effect of rotation on FIV. The oscillation of cylinder is enhanced significantly by rotation in flow direction, but the opposite phenomenon is observed in cross flow direction. The maximum amplitudes of 0.363D in flow direction and 0.611D in cross flow direction are obtained. The skewing of vibration in cross flow direction is observed due to Magnus effect and the time-averaged displacement of rotating cylinder in cross flow direction increases monotonously with the rotation rate α. Meanwhile, same frequencies in two directions are observed for rotating cylinder, which leads to closed-loop trajectories that are quite different from the situations of non-rotating cylinder. For different α, the frequency ratios in cross flow direction stay around 1.1 when U*≥6.0 except for α ≥ 1.0. The trajectories also reflect the instability of vibration for high reduced velocity. Due to the asymmetry generated by the rotation, large lift and drag force coefficients are obtained. The 2S and U vortex patterns are observed for the FIV of rotating circular cylinder.