Time-Domain Nonlinear Wave-Current Interaction with A Steep Wave Riser Considering Internal Flow Effect

• Published in: China ocean engineering Vol. 35; no. 3; pp. 410 - 421
• Main Authors: Tang, Lian-yang, Cheng, Yong, Ji, Chun-yan
• Format: Journal Article
• Language: English
• Published: Nanjing Chinese Ocean Engineering Society 01.07.2021; Springer Nature B.V; Nippon Kaiji Kyokai (China) Co.,Ltd,Shanghai 200336,China%School of naval architecture and ocean engineering,Jiangsu University of Science and Technology,Zhenjiang 212003,China; School of naval architecture and ocean engineering,Jiangsu University of Science and Technology,Zhenjiang 212003,China
• Subjects: Bending moments; Buoyancy; Catenary; Coastal Sciences; Configurations; Coordinate systems; Coordinates; Current velocity; Deep water; Deformation; Density; Dynamic response; Dynamical systems; Engineering; Finite element method; Fluid- and Aerodynamics; Internal flow; Iterative methods; Marine & Freshwater Sciences; Mathematical analysis; Mechanical properties; Mitigation; Nonlinear dynamics; Nonlinear response; Nonlinear waves; Numerical and Computational Physics; Oceanography; Offshore Engineering; Segments; Simulation; Steel; Tension; Time domain analysis; Wave height; Wave-current interaction; time-domain finite element method (FEM); steep wave riser (SWR); wave-current interaction; nonlinear dynamic response
• ISSN: 0890-5487; 2191-8945
• DOI: 10.1007/s13344-021-0037-9

The nonlinear dynamic response induced by the wave-current interaction on a deepwater steep wave riser (SWR) is numerically investigated based on a three-dimensional (3D) time-domain finite element method (FEM). The governing equation considering internal flow is established in the global coordinate system. The whole SWR consists of three segments: the decline segment, buoyancy segment and hang-off segment, in which the buoyancy segment is wrapped by several buoyancy modules in the middle section, leading to the arch bend and sag bend. A Newmark-β iterative scheme is adopted for the accurate analysis to solve the governing equation and update the dynamic response at each time step. The proposed method is verified through the published results for the dynamic response of steel catenary riser (SCR) and static configuration of steel lazy wave riser (SLWR). Simulations are executed to study the influence of wave height, current velocity/direction, internal flow density/velocity and top-end pressure on the tension, configuration and bending moment of the SWR. The results indicate that the influence of the current on the configuration and mechanical behavior of the SWR is greater than that of the wave, especially in the middle section. With increasing current velocity, the suspending height of the middle section drops, meanwhile, its bending moment decreases accordingly, but the tension increases significantly. For a fixed external load, the increasing internal flow density induces the amplification of the tension at the hang-off segment and the mitigation at the decline segment, while the opposite trend occurs at the bending moment.