Wake-induced response of vibro-impacting systems

This study investigates the bifurcation behaviour of wake-induced vibro-impacting systems considering fluid-structure interaction (FSI). The primary structure and the near wake dynamics are modelled as a harmonic oscillator a Van der Pol oscillator, respectively, and are weakly coupled to each other. A non-deformable barrier obstructing the motion of the oscillator gives rise to the impacting dynamics. Instantaneous velocity reversal occurs when the structure impacts with this barrier. Qualitative changes in the dynamical behaviour of this system are investigated in the context of discontinuity-induced bifurcations (DIBs) resulting from the interaction of fluid flow and non-smoothness from the primary structure. Phenomenological behaviour like co-existence of attractors and period-adding cascades of limit cycles leading to chaos are examined. Existence of these phenomena are demonstrated via stability analysis using Floquet theory and associated Lyapunov spectra. A new approach to capture the impact dynamics of the hybrid system through a transverse discontinuity map is proposed. Orbits obtained using this new algorithm is demonstrated to accurately predict both stable and chaotic regimes as observed from the corresponding bifurcation diagrams. The effect of the presence of non-smoothness on the lock-in phenomenon in systems that involve fluid-structure interaction is studied for the first time