DPIV in the wake of a tandem arrangement of two flexible circular cylinders

Visualization of the wake of a system of two circular cylinders in tandem is presented through Digital Particle Image Velocimetry results in a plane perpendicular to the models' axes. Both cylinder models have an aspect ratio (length over diameter) of almost 100, a mass ratio (mass divided by mass of displaced fluid) under 2, and they are flexible and free to move in the in-line and cross-flow directions. A supporting structure provided attachment of both models through universal joints at each end and the cylinders were exposed to a uniform flow profile over the lower 45% of their lengths, producing vortex-induced vibrations with wake interactions. The centre to centre separation between the models could be varied and data is shown here for three separations of 2, 3 and 4 diameters.