Vortex-induced vibration of a flexible pipe under oscillatory sheared flow

An experimental apparatus for studying vortex-induced vibration (VIV) of a flexible pipe was designed and constructed in an ocean basin. A VIV test of a tensioned flexible pipe in oscillatory sheared flow (OSF) was performed based on this rotation rig. One end of the test pipe is fixed, and one end is forced to oscillate harmonically with various amplitudes and periods. The results show that VIV under OSF exhibits amplitude modulation and hysteresis phenomena. A critical Keulegan-Carpenter (KC) number is proposed to describe the occurrence of modulated VIV under OSF. The experimental results provide benchmark data for future VIV prediction research.