Linear analysis of the dynamic response of a riser subject to internal solitary waves

• Published in: Applied mathematics and mechanics Vol. 44; no. 6; pp. 1023 - 1034
• Main Authors: Tan, Dalin, Wang, Xu, Duan, Jinlong, Zhou, Jifu
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.06.2023; Springer Nature B.V; School of Engineering Sciences,University of Chinese Academy of Sciences,Beijing 100049,China; Beijing Electro-Mechanical Engineering Institute,Beijing 100074,China%Key laboratory for Mechanics in Fluid Solid Coupling Systems,Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190,China%Key laboratory for Mechanics in Fluid Solid Coupling Systems,Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190,China; Key laboratory for Mechanics in Fluid Solid Coupling Systems,Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190,China
• Edition: English ed.
• Subjects: Applications of Mathematics; Classical Mechanics; Dynamic response; Dynamical systems; Fluid- and Aerodynamics; Linear analysis; Mathematical Modeling and Industrial Mathematics; Mathematics; Mathematics and Statistics; Mode superposition method; Nonlinear dynamics; Nonlinear response; Partial Differential Equations; Risers; Solitary waves; Water depth; linear analysis; dynamic response; O352; internal solitary wave (ISW); riser; 74F10; internal solitary wave(ISW)
• ISSN: 0253-4827; 1573-2754
• DOI: 10.1007/s10483-023-3006-9

The flow field induced by internal solitary waves (ISWs) is peculiar wherein water motion occurs in the whole water depth, and the strong shear near the pycnocline can be generated due to the opposite flow direction between the upper and lower layers, which is a potential threat to marine risers. In this paper, the flow field of ISWs is obtained with the Korteweg-de Vries (KdV) equation for a two-layer fluid system. Then, a linear analysis is performed for the dynamic response of a riser with its two ends simply supported under the action of ISWs. The explicit expressions of the deflection and the moment of the riser are deduced based on the modal superposition method. The applicable conditions of the theoretical expressions are discussed. Through comparisons with the finite element simulations for nonlinear dynamic responses, it is proved that the theoretical expressions can roughly reveal the nonlinear dynamic response of risers under ISWs when the approximation for the linear analysis is relaxed to some extent.