Effect of stochastic parametric noise on vortex induced vibrations

Abstract

The role of parametric noise in altering the nonlinear dynamical behaviour of a circular cylinder undergoing vortex induced vibrations (VIV) is examined in this paper. Presence of parametric noise in the nonlinear VIV system is seen to bring in major qualitative and quantitative changes in response dynamics compared to its deterministic behaviour. Noise is seen to excite multiple frequencies in the response in the pre and post lock-in regimes and bring in new dynamical states. Noise intensity is seen to play a major role in dictating the qualitative nature of the new dynamical features that arise due to noise. Presence of low intensity noise gives rise to aperiodicity that resembles a quasi-periodic behaviour. Noise induced intermittency, dynamical state in which a system switches randomly between two near-by attractors is observed under the effect of high intensity noise. Nonlinear time series tools have been found effective in characterising the dynamical differences of different qualitative states for the present problem. Recurrence based time series tools have been especially insightful. Their adoption in a stochastic VIV system is also novel to the best of the authors’ knowledge and provides a fresh perspective to the problem.