Surge motion of top-end platform induced by periodic wave makes marine flexible riser encounter equivalent sheared-oscillatory flow, under which the Vortex-induced Vibration (VIV) response will be more complicated than pure sheared flow or oscillatory flow cases. Based on a time domain force-decomposition model, the VIV response characteristics under sheared-oscillatory flows are investigated numerically in this paper. Firstly, the adopted numerical model is validated well against laboratory experiments under sheared flow and oscillatory flow. Then, 20 sheared-oscillatory flow cases with different oscillation periods and top maximum current velocities are designed and simulated. Under long and short oscillation period cases, the structural response presents several similar features owing to the instantaneous sheared flow profile at each moment, but it also has some different patterns because of the differently varying flow field. Finally, the effects and essential mechanism of oscillation period and top maximum current velocity on VIV response are discussed systematically.

周期波引起的高端平台的激增运动使海洋柔性立管遇到等效的剪切振荡流，在这种情况下，涡激振动（VIV）的响应将比纯剪切流或振荡流情况更为复杂。本文基于时域力分解模型，对剪切振荡流下的VIV响应特性进行了数值研究。首先，在剪切流和振荡流下，采用的数值模型在实验室实验中得到了很好的验证。然后，设计并模拟了20个具有不同振荡周期和最大最大流速的剪切振荡流工况。在长短振荡周期的情况下，由于每个时刻的瞬时剪切流动剖面，结构响应呈现出几个相似的特征，但是由于流场的变化，它也有一些不同的模式。最后，系统地讨论了振荡周期和最大最大速度对VIV响应的影响和基本机理。