On the onset of bifurcation and nonlinear characterization of vortex-induced vibrations under varying initial conditions

Abstract

We perform numerical simulations to investigate the hysteresis phenomenon near the bifurcation points of the synchronization region leading to vortex-induced vibrations. We characterize the response using nonlinear dynamics tools. We find an unstable region at both ends of the synchronization regime where the response depends on initial conditions. Unlike previous studies, the focus of the current research is to analyze the effect of the structure’s initial condition on the VIV response. We vary the initial velocity of the cylinder and observe the response of transverse displacement and lift coefficient as a function of Reynolds number. We observe that in the pre-synchronous and synchronous regimes, the cylinder response is always period-1 at cylinder’s natural frequency. However, in the post-synchronous regime, the response is period-n where $$n > 1$$. Thus, bifurcation diagrams depicts the variation of the onset of synchronization and its spectrum over the range of Reynolds number.