Effect of noise on vortex-induced vibrations of circular cylinders

In this study, we examine the effect of uniformly distributed noise superimposed on a steady, incompressible mean flow, past a circular cylinder undergoing transverse oscillations. We use a Duffing–Van der pol combined system for the present investigation in order to model the associated nonlinear behavior. We observe that as we vary the mean velocity as the bifurcation parameter, noise brings in major qualitative and quantitative changes on the structural response of the system compared to the deterministic cases. Noise induces new dynamical states in this vortex-induced vibration (VIV) system. The noise, depending on its coefficient of intensity, has a role in advancing the lock-in regime. The time histories of the response prior and post lock-in show different dynamics compared to the deterministic cases. Also, depending on the intensity of the noise coefficient, the probability density functions of the response amplitude also undergo qualitative and quantitative changes. We investigate the existence of P (phenomenological)-bifurcations in the VIV system by analyzing the joint probability density functions and quantify the response using Shannon entropy.