Manifestation of additional frequencies in vortex induced vibrations in the presence of noise

In this study, we examine the effect of random input fluctuations in the mean flow to a circular cylinder undergoing transverse oscillations. A Duffng-Van der pol combined system has been used to model the structure and wake oscillators in the VIV system. We observe that the addition of noise brings in major qualitative and quantitative changes on the structural response of the system compared to the deterministic cases. It has been observed that the stochastic system is always influenced by the presence of structural frequency. In contrast, the system under mean flow condition aligns with the structural frequency, only in the lock-in range. This feature is seen as noise exciting multiple frequencies in the response of the cylinder in the pre lock-in and post lock-in regimes.