Response dynamics of a freely oscillating cylinder under the effect of noise

Abstract

The present work revisits free vibration of a circular cylinder undergoing Vortex Induced Vibrations situations in terms of a two dimensional CFD framework, under the effect of a random input flow. Randomness in the oncoming fluid and its effect on the overall dynamical behaviour of the system is a likely scenario that has not received its due attention in the community. The analytical models, prove to be good enough in capturing the qualitative behaviour of the responses, with appropriate tuning of parameters. The effect of stochastic fluctuations in the oncoming flow is analyzed on the structural amplitude. Noise seems to have major effects on the structural amplitude, the onset and range of lock-in. A stability analysis of the structure for both deterministic and stochastic cases is complete only when the spatial and temporal evolution of the wake pattern is also considered. In this context, a Navier Stokes high fidelity solver is used, to determine the bifurcation behavior of the system for deterministic and stochastic cases. Effects of a few relevant system parameters such as Reynolds number, structural stiffness have been studied to resolve the qualitative and quantitative changes in the response dynamics. The intensity of noise seems to have major effects in determining the quality and quantity of the response.