ABSTRACT

The nonlinear dynamic behaviour of steep wave riser (SWR) subjected to the top harmonic motions considering the effect of the internal flow is numerically investigated using a three-dimensional (3D) time-domain finite element method (FEM) based on the slender flexible rod theory. In this numerical model, the riser which satisfies geometric nonlinearity is divided into three segments: decline segment, buoyancy segment and hang-off segment and the effect of the internal flow is also incorporated into motion equation using plug flow. A Newmark-β integral method is applied to update the dynamic responses at each time step. The published results for the static/dynamic performance of the steel flexible riser are used to validate the present numerical method. Numerical simulations are conducted to investigate the dependence of the tension, displacement and bending moment on the design parameters. The top motion amplitude/period, buoyancy length and internal flow density/velocity/top pressure are discussed respectively.

摘要

采用基于细长柔性杆的三维（3D）时域有限元法（FEM）数值研究考虑内部流动影响的陡波立管（SWR）的非线性动力行为。理论。在该数值模型中，满足几何非线性的立管分为下降段、浮力段和悬垂段三段，并利用塞流将内部流动的影响纳入运动方程。应用 Newmark-β 积分方法更新每个时间步的动态响应。已发表的钢制柔性立管的静态/动态性能结果用于验证目前的数值方法。进行数值模拟以研究张力的依赖性，位移和弯矩的设计参数。分别讨论了顶部运动幅度/周期、浮力长度和内部流动密度/速度/顶部压力。