The present study proposes a time domain model for the Vortex-induced Vibration (VIV) simulation of a catenary riser under the combination of the current and oscillatory flow induced by vessel motion. In this model, the hydrodynamic force of VIV comprises excitation force, hydrodynamic damping and added mass, which are taken as functions of the non-dimensional frequency and amplitude ratio. The non-dimensional frequency is related with the response frequency, natural frequency, lock-in range and the fluid velocity. The relatively oscillatory flow induced by vessel motion is taken into account in the fluid velocity. Considering that the added mass coefficient and the non-dimensional frequency can affect each other, an iterative analysis is conducted at each time step to update the added mass coefficient and the natural frequency. This model is in detail validated against the published test models. The results show that the model can reasonably reflect the effect of the added mass coefficient on the VIV, and can well predict the riser’s VIV under stationary and oscillatory flow induced by vessel motion. Based on the model, this study carries out the VIV simulation of a catenary riser with harmonic vessel motion. By analyzing the bending moment near the touchdown point, it is found that under the combination of the ocean current and oscillatory flow the vessel motion may decrease the VIV response, while increase the excited frequencies. In addition, the decreasing rate of the VIV under vessel surge is larger than that under vessel heave at small vessel motion velocity, while the situation becomes opposite at large vessel motion velocity.

本研究提出了一种时域模型，用于在血管运动引起的电流和振荡流的共同作用下，对悬链提升管进行涡流诱发的振动（VIV）模拟。在该模型中，VIV的水动力包括激振力，水动力阻尼和附加质量，它们是无量纲频率和振幅比的函数。无量纲频率与响应频率，固有频率，锁定范围和流体速度有关。在流体速度中考虑了由血管运动引起的相对振荡的流动。考虑到增加的质量系数和无量纲频率会相互影响，因此在每个时间步进行迭代分析以更新增加的质量系数和固有频率。该模型已针对已发布的测试模型进行了详细验证。结果表明，该模型可以合理地反映附加质量系数对VIV的影响，并且可以很好地预测在船舶运动引起的平稳和振荡流动下立管的VIV。在此模型的基础上，本研究对具有谐波容器运动的悬链提升管进行了VIV仿真。通过分析着陆点附近的弯矩，发现在洋流和振荡流的共同作用下，船舶运动可能会降低VIV响应，同时增加激发频率。另外，在较小的船舶运动速度下，船舶喘振下VIV的下降率要大于在船舶升沉下的VIV下降率，而在较大的船舶运动速度下，则相反。