Numerical Simulation Of The Hydrodynamic Behaviour Of The Square Net Cage For Flatfish

At present, the flatfish with special quality such as fast growth, high protein and low calories, etc has become a very important mariculture species in China, and an industry of mariculture has developed in the north coastal regions. However, the traditional land-based flatfish aquaculture in China caused high energy consumption and damaged groundwater resource seriously. Consequently, it is imperative to develop offshore flatfish aquaculture. As we all known, the net cages exposed to open ocean area have to suffer much more complicated sea conditions. In order to withstand the new challenge, the performance of cages need to be improved, and the study of the dynamic characteristics of the net cage system is around the corner, which is one of most important security factors for flatfish aquaculture. In this dissertation, a numerical model of the square gravity cage for flatfish culture is developed to replace the traditional methods of actual observation and model test in some extent, which is helpful to save time and reduce costs.This paper is sponsored by the National Natural Science Foundation Project, the National863High Technology Project, the Specialized Research Fund for the Doctoral Program of Higher Education of China, the Innovative Research Groups of the National Natural Science Foundation of China, the Earmarked Fund for Modern Agro-industry Technology Research System and the Shandong Foundation for Development of Science and Technology, China. In the dissertation, a numerical model based on rigid body kinematics and lumped mass method is built to simulate the hydrodynamic behavior of the float collar, the sinker system and the mooring system, which are the main parts to withstand the forces acting on the net cage structure.The contents of the thesis are mainly composed of five parts. The first part is about the general introduction of the background, development, prospects and purpose of the research of net cages for flatfish. In the second part, the basic numerical method and theory of net cage system is given, which will be applied in the following sections. In the third part, after the validity of the simulated results is verified, the numerical simulations of the square gravity cage for flatfish exposed to waves are carried out and comparison is made with the round gravity cage. In the fourth part, the hydrodynamic properties of the square gravity cage for flatfish are investigated in current by numerical model, and the research content are as the same as the third part. At the end of the dissertation, the conclusion is given.