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http://dx.doi.org/10.26748/KSOE.2018.2.32.1.001

Study on Optimal Damping Model of Very Large Offshore Semi-submersible Structure  

Lee, Hyebin (Multidisciplinary Graduate School Program for Wind Energy, Jeju National University)
Bae, Yoon Hyeok (Deptartment of Ocean System Engineering, Jeju National University)
Kim, Dongeun (Faculty of Wind Energy Engineering Graduate School, Jeju National University)
Park, Sewan (Korea Research Institute of Ships and Ocean Engineering)
Kim, Kyong-Hwan (Korea Research Institute of Ships and Ocean Engineering)
Hong, Keyyong (Korea Research Institute of Ships and Ocean Engineering)
Publication Information
Journal of Ocean Engineering and Technology / v.32, no.1, 2018 , pp. 1-8 More about this Journal
Abstract
In order to analyze the response of the offshore structure numerically, the linear potential theory is generally applied for simplicity, and only the radiation damping is considered among various damping forces. Therefore, the results of a numerical simulation can be different from the motion of the structure in a real environment. To reduce the differences between the simulation results and experimental results, the viscous damping, which affects the motion of the structure, is also taken into account. The appropriate damping model is essential for the numerical simulation in order to obtain precise responses of the offshore structure. In this study, various damping models such as linear or quadratic damping and the nonlinear drag force from numerous slender bodies were used to simulate the free decay motion of the platform, and its characteristics were confirmed. The optimized damping model was found by comparing the simulation results to the experimental results. The hydrodynamic forces and wave exciting forces of the structure were obtained using WAMIT, and the free decay test was simulated using OrcaFlex. A free decay test of the scale model was performed by KRISO.
Keywords
Linear damping; Quadratic damping; Nonlinear drag; Semi-submersible; Coupled analysis;
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