Spatiotemporal dynamics of a vortex induced vibration system in the presence of stochastic inflow fluctuations

In this study, influence of stochastic parametric inflow on the spatiotemporal dynamics of a vortex induced vibration system has been examined. The study has been carried out using an incompressible Navier–Stokes based flow solver at a Reynolds number of 100, and it highlights the role of stochastic fluctuations/noise in triggering complex spatiotemporal dynamics in the laminar vortex shedding regime. Wavelets and space–time plots were used to analyse the spatiotemporal data. Noise has been seen to advance the instability regime and alter the frequency characteristics of the response by exciting additional system frequencies, which in turn affects the phase dynamics as well. The study has also revealed that the time scale of the input is an important factor in deciding the dynamics. A short time-scaled noise can trigger aperiodic dynamics, whereas, a long time-scaled input invokes switch states or intermittent states. Noise affects the separation behaviour of the near-field vortices by delaying or advancing it, depending on the regime of operation. For the long time-scaled case, the flow-field becomes a combination of strong or weak von Kárman streets and transitionally disordered wakes. With the short time-scaled noise, the flow-field is predominantly disordered and characterised by phenomena such as vortex pairing and deflected wakes.