Flow-induced vibrations of a pair of rigidly linked circular cylinders in cross-flow*

Vortex-induced vibration (VIV) experiments with an elastically mounted low mass-damping system of two cylinders have been conducted. The system consists of a pair rigidly linked circular cylinders with the same mass m, length L and diameter D, that are submerged in a uniform flow with velocity U, generated by the free surface channel at the Laboratory for Fluid-Structure Interaction (LIFE) of the Universitat Rovira i Virgili. The cylinders are separated a distance S_x in the flow direction and S_y in the perpendicular to the flow or transverse direction. The set-up hangs from an air bearing system to minimise friction when oscillating. Restoring forces are provided by a set of springs with stiffness constant k.

In one of the con configurations studied, different S_x and S_y were used, ranging from the tandem or in-line positioning to the side-by side configuration. The dynamic response was fully characterized, including measurements of amplitude and frequency of oscillation, as well as fluid excitation. The experiments covered a large parametric space, consisting of variations in the separations and the free stream velocity, leading to a wide range of reduced velocities and Reynolds numbers. The rich fluid-structure interaction phenomena observed in the experiments will be discussed and analyzed in detail.