Fluid excitation of an oscillating circular cylinder in cross-flow

This paper presents an experimental technique developed to identify the fluid excitation force of a circular cylinder during Vortex-Induced Vibrations (VIV). To this end, an actuator is used to provide controlled damping and a Van der Pol model is proposed to describe the fluid excitation force, where the associated parameters are identified from experiments by a least square fitting. The Reynolds number was in the range 1650-4950, and the technique is validated with experimental free vibration data of an elastically supported circular cylinder. Also, comparison with free vibration measurements from other experiments carried out with similar Reynolds numbers is presented.