JZUS - Journal of Zhejiang University SCIENCE

Journal of Zhejiang University SCIENCE A 2008 Vol.9 No.5 P.654-663

http://doi.org/10.1631/jzus.A0720016

Hydrodynamic coefficients of a simplified floating system of gravity cage in waves

Author(s): Chang-wen WU, Fu-kun GUI, Yu-cheng LI, Wei-huan FANG
Affiliation(s): Marine Science School, Zhejiang Ocean University, Zhoushan 316000, China; more
Corresponding email(s): gui2237@163.com
Key Words: Gravity cage, Floating system, Hydrodynamic coefficients, Waves

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Abstract: Numerical simulation and experimental tests were carried out to examine the hydrodynamic behaviors of a double-column floating system of gravity cage under wave conditions. A floating system of gravity cage can be treated as a small-sized floating structure when compared with the wavelengths. The main problem in calculating the wave loads on the small-sized floating structure is to obtain the reasonable force coefficients, which may differ from a submerged structure. In this paper, the floating system of gravity cage is simplified to a 2D problem, where the floating system is set symmetrically under wave conditions. The motion equations were deduced under wave conditions and a specific method was proposed to resolve the problem of wave forces acting on a small-sized floating system of gravity cage at water surface. Results of the numerical method were compared with those from model tests and the hydrodynamic coefficients C_n and C_ were studied. It is found that C_n ranges from 0.6 to 1.0 while C_ is between 0.4 and 0.6 in this study. The results are useful for research on the hydrodynamic behavior of the deep-water gravity sea cages.

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