Vortex- and wake-induced vibrations of a tandem arrangement of two flexible circular cylinders with far wake interference

The dynamic response of two flexible cylinders in tandem arrangement partially immersed in a uniform flow is analysed. The centre-to-centre separations, larger than 4 and up to 8 diameters, were chosen to fall in the regime in which two separate wakes exist behind each one of the models. For the cases presented here, it has been confirmed that the main excitation mechanism is wake-induced vibration (WIV). The rear cylinder shows large amplitudes of response, at reduced velocities over the expected ones at lock-in when a cylinder is undergoing VIV being isolated. This type of response has been also observed by other researchers in experiments with flexibly mounted cylinders in the wake of stationary ones, we also provide data here, for cases with the front cylinder being stationary. (C) 2011 Elsevier Ltd. All rights reserved.