In order to solve the problem of excessive calculation of mesh deformation and mesh tension in numerical simulation, an improved mesh group method based on centralized mass method is proposed in this paper. The improved method keeps the volume and mass of the mesh before and after the mesh group, and the deformation of the mesh after the improved method is similar to that before the mesh group by adjusting the hydrodynamic coefficient and axial stiffness. Based on the potential flow theory, the numerical model of "Shenlan No.1" was established to analyze the strain and deformation of the mesh under different flow velocity, wave steepness and compactness. The results show that the mesh tension and deformation increase with the increase of flow rate and compactness, but the tension uniformity decreases with the increase of flow rate and compactness. The maximum tensile value of the mesh appears in the middle area of the top tie point, and the maximum deformation value appears in the middle and upper area of the mesh. The top tie point breakage and bottom tie point breakage have the greatest influence on the mesh. The improved mesh clustering method is accurate and effective, and has good reference value for improving the simulation efficiency and calculation accuracy of the cage hydrodynamics. The results can provide some theoretical support for far-reaching Marine aquaculture.

This paper mainly studies the transformation technology, kinematics and dynamics characteristics of a new offshore wind turbine installation ship. The transformation process is mainly for the semi-submersible barge, through the installation of "lap joint device" and jacket platform on the bow, and the deployment of anchor, ballast water and mooring cable on the stern, to ensure that the installation of offshore wind turbines meet the requirements of the specification. Research on kinematics and dynamics based on potential flow theory and establish frequency domain-time domain model of wind power installation ship by using hydrodynamic analysis software AQWA to verify the numerical model and provide test data for real sea state operation through peak response; finally, further analyze different influencing factors under the working sea area with AQWA, including exploring the kinematic and dynamic response of wind speed, wind wave current angle, wave period and other parameters to the working conditions. The results show that the lapping installation method is suitable for the installation of wind turbines due to its small amplitude of motion and dynamic response of the hull under the environmental conditions in the offshore waters of China. It also shows that this reform method has engineering application value. The response amplitude of the hull is less affected by the wind speed; the angle of wind, wave and current will have a greater impact on the response amplitude of the installation vessel, the amplitude in the direction of facing wave is smaller, while the amplitude in the direction of beam wave and following wave is larger; as the peak period of wave spectrum increases from 6 s to 10 s, the response amplitude becomes larger and larger. Beam waves and sea conditions with large periods shall be avoided as far as possible during engineering operations.