Flow-induced vibrations of a side-by-side arrangement of two flexible circular cylinders

Laboratory experiments with a side-by-side arrangement of two vertical, high aspect ratio (length over diameter) and low mass ratio (mass over mass of displaced fluid) cylinders, pin-jointed at the ends and vibrating at low mode number, were carried out in a free-surface water channel. The dynamic response of the models under two different wake interference situations is presented here. Initially, one of the cylinders was fixed and the other was completely free to move. In a second battery of experiments both cylinders were free to vibrate. A very large parameter space was covered by varying the free-stream flow speeds, the natural frequencies of the system and the separation between the models, allowing the identification of vortex-induced vibrations (VIV) and wake-coupled VIV (WCVIV). Amplitudes, frequencies and phase synchronisation between the models are presented.