| Nowadays the abyssal aquaculture cages are developing rapidly and they are playing an increasingly important role in the sea farming industry in China. This paper describes the wave forces on columniform-lift offshore cages and gives the kinetic simulation of this kind of cages on the basis of summarizing the actuality of abyssal aquaculture cages in China. Using a series of equations in mechanics such as Newton Law and Momentum Rule, the kinetic geometrical model is gained and the dynamic equations of the columniform-lift offshore cage are presented, in addition, the numerical solution is obtained. Calculating method of nonlinear wave forces on bigger scale structure and Morison equation are used in the analysis of wave forces. With the variation of wave -length, wave height and wave period, the hydrodynamic forces change according the regulation that the horizontal wave force is much larger than the vertical wave force, and the wave force changes remarkably with the variation of wave height. This paper also describes the variation rules of the submergence depth. With the variation of wave -length, wave- height and wave-period, the submergence depth of the columniform-lift offshore cage varies regularly. The conclusion is that the wave forces vary rapidly in shallower sinkage and vary slowly in deep-seated submergence depth. The best submergence depth is about 6 to 8 meter of the instances in the paper. It will be different with the different fabric cages. The reference point should be adopted is the mild point in the submergence depth -wave force curve. This paper gives one emluator according to the kinetic geometrical model of the columniform-lift offshore cage. By analyzing the emluator, the conclusion is that the displacement of the cage change rapidly and in the end it will sway periodically at a relative immobile position, meanwhile, there is a obliquity of the cage because of the action of wave forces and the obliquity will sway periodically at a relative steady angle, too. |
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