Numerical Simulation Of Dynamic Behavior Of Offshore Mussel Raft Under Wave And Current Action

Marine aquaculture is the main part of Chinese fisheries economics. The main modes of production of the marine aquaculture are coastal land-based aquaculture, tidal flats aquaculture and inner bay aquaculture. Nowadays the marine aquaculture is deeply affected by coastal water environment. Due to the serious damage to the marine environment and the worse aquaculture condition, the quality of aquaculture declined and the mortality increased. The quality and safety problems have become more severe, at the same time the emission problems are also criticized. Therefore, the raft aquaculture should be moved from coastal waters to the deep sea and open ocean to develop, which has become an inevitable choice. The raft aquaculture has a long history in China, however, the basic research in the open sea is not adequate in the face of extreme condition such as high waves and strong currents. Thus, this research analyzed the hydrodynamic behavior of offshore raft aquaculture facilities, with the support of Nature Science Foundation of China.In this dissertation, a numerical model of raft aquaculture facilities is developed, based on lumped mass method, rigid body kinematics and improved Morison equation. The numerical solution can be carried out using the fourth-order Runge-Kutta method and the hydrodynamic behavior of raft aquaculture facilities in wave force can be obtained. The results of the numerical simulation were compared with the results in physical experiment. The comparison is used to verify the validity of the numerical simulated mode. Based on numerical simulation method, the hydrodynamic behaviors of raft aquaculture facilities are investigated in the influences of wave, current and the combination of wave and current. Also the hydrodynamic behaviors of raft aquaculture facilities in irregular wave force and the hydrodynamic behaviors of the submerged submersible raft are investigated.The contents of the dissertation are mainly composed of five parts. In the first chapter, the back ground and the significance of this dissertation are introduced, and the relative researches and the advance are also presented. The content and target of this research are given based on the previous researches. In the second chapter, the basic numerical mode and theory are introduced. The numerical simulation methods of the main components of raft aquaculture facilities are analyzed. In the third chapter, the hydrodynamic behaviors of raft aquaculture facilities are investigated in the influences of wave, current and the combination of wave and current. The results in physical experiment are used to verify the validity of the numerical simulation results. At the same time, the influences of wave height and periodic variation on the movement and force of raft aquaculture facilities are compared. In the fourth chapter, the spectrum analysis method for the random data is introduced. The hydrodynamic behaviors of raft aquaculture facilities in irregular wave force are investigated and the hydrodynamic behaviors of the submerged submersible raft are compared. In the fifths chapter, the hydrodynamic behaviors of submersible raft are investigated and the influences of depth on the motion amplitude and mooring force are analyzed. At the end of the dissertation, the achievements of this study are summarized, and the further study and prospects are given.