Numerical Study on the Interaction of In-Line and Cross-Flow VIV

The fatigue damage induced by in-line vibration and cross-flow vibration was addressed in this paper using a statistical methodology and also the amplitude ratio. Traditionally, engineers have concentrated on cross-flow vibrations, assuming that in-line oscillations are less important. In-line amplitudes are generally lower, but the high-frequency nature of these oscillations can result in significant fatigue damage. The ratio between amplitude of in-line oscillation and cross-flow vibration in four different current velocity was studied, and also be analyzed by statistical method. For the fatigue analysis, the ratio between damage of in-line and cross-flow was obtained, the maximum ratio curve and the mean ratio curve were presented. The conclusions presented the fatigue damage caused by in-line vibration couldn’t be neglected, especially in low velocity.