Nonlinear time-domain dynamic analysis of three-dimensional deepwater steep wave riser subjected to top motions with internal flow effects

摘要

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-beta 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.

关键词