Vortex-excited vibration of a circular cylinder in planar oscillating flow

Laboratory investigation has been made for a comprehensive study of the dynamic transverse response of a circular cylinder in planar oscillating flow. The test cylinder, 0.03 m in diameter and 0.48 m in length, is mounted horizontally at the mid-point of the water depth and is supported flexibly by a spring in the transverse direction. The variations of the transverse response of the test cylinder with frequency ratio f(d)/f(nw) (f(d): frequency of oscillatory incident flow; f(nw): natural frequency of the test cylinder in still water) and Keulegan-Carpenter number, KC, as the function of typical combined mass ratio-damping parameter, Scruton number K-xp, are obtained in the range of 4 < KC < 20 and 0.75 < K-sp < 14.5. The appearance of 2 types of peak in the amplitude of vortex-excited vibration, which occurs similarly in the vortex-excited vibration of a vertical circular cylinder in waves, is also recognized for the right value of typical Scruton number K,P.