Three-dimensional nonlinear vortex-induced vibrations of top-tension risers considering platform motion. (1st November 2022)

• Record Type: Journal Article
• Authors: Zhang, Bin; Chai, Yuyang; Li, Fengming; Chen, Yongxin
• Is Part Of: Ocean engineering. Volume 263(2022)
• Publication Date: 2022-11-01
• Subjects: Vortex-induced vibration -- Top-tension riser -- Platform motion -- van der Pol equation -- Coupling response; Ocean engineering -- Periodicals; Ocean engineering; Periodicals; 620.4162
• DOI: 10.1016/j.oceaneng.2022.112393
• Languages: English
• ISSNs: 0029-8018

Abstract

Abstract: A novel three-dimensional (3-D) dynamic model considering nonlinearity of tension is proposed to explore in-line (IL), cross-flow (CF) and axial (AX) vortex-induced vibration (VIV) responses of riser under platform motion. The interaction between riser and external flow is simulated by the van der Pol equation, and the nonlinear equations of motion are established by Hamilton's principle and the Galerkin method, and solved by Runge-Kutta method. The influences of heave and swing motions of platform on VIV responses of the riser are investigated. It is found that for large velocity of external flow, the axial displacement of riser results in an increase in IL excitation mode and also an increase in IL oscillating displacement. When the riser is excited by swing motion of platform, with the increase of excitation amplitude, the maximum response amplitudes will also increase in all the three directions, and the amplitudes in high frequency domain increase more obviously. Combined effect of heave and swing motions of the platform results in the increase of VIV amplitudes in IL and AX directions, and combined action of forced and parametric excitations has little effect on response amplitude of riser in CF direction. Highlights: A novel 3-D nonlinear dynamic model is proposed to study VIV properties of riser. Combined effects of parametric and forced excitations on VIV properties are explored. Larger forced excitation leads to larger maximum responses in all the three directions. Axial coupling effect on the VIV responses of the riser needs to be considered.