Study On Hydrodynamic Analysis Of Semi-submersible With Varying Water Depth

China has a vast ocean area.The reefs in the South China Sea are often surrounded by coral reef plates hundreds or even thousands of meters wide.These reefs and coral reef plates not only have abundant biological resources,tourism resources and mineral resources,but also play a key role in protecting islands and eliminating waves.In order to facilitate the development of marine resources,various structures such as semi-submersible platforms can be arranged around the reefs as floating bases.Many large semi-submersible platforms can also be connected to form a floating airport at sea,so it is of great significance to study the hydrodynamic characteristics of multi-floating bodies under wave action.Based on the analysis of wave motion on submerged reefs by using wave theory,the paper further studies hydrodynamic characteristics of floating bodies under reef terrain.The main parts are as follows:1.This paper introduces the basic flow of fluid mechanics analysis using ANSYS/Workbench,studied the use of UDF in Workbench/FLUENT,and compiled codes of forced heave motion,forced rolling motion and free motion of floating body.2 When studying the hydrodynamic characteristics of semi-submersible platform with varying water depth in wave numerical flume,ANSYS/ICEM is used for modeling and meshing.In order to improve the accuracy and convergence of the calculation,the mesh generation of the model and the application conditions of the dynamic mesh in the fluid domain are discussed.3.In the numerical wave flume model,the reef is simulated by porous medium model,the free surface is simulated by multiphase flow and VOF model,and the free motion of the object under wave action is simulated by the method of dense mesh and time step reduction.FLUENT simulation is more reasonable than the boundary element method based on the theory of diffraction when the floating body is located near the island reef in the flume,considering the viscous force of the fluid.4.This paper studies a special multi-floating body system consisting of a moving floating body and a fixed permeable reef.When the floating body does not move,forced heave motion,forced rolling motion and free motion,the waveform before and after the reef and the wave height variation of the free surface,as well as the velocity distribution of the floating body in the reef terrain are calculated.The effects of dynamic pressure and wave force on floating bodies with and without reefs are compared.It is found that the topography of the island reef will interfere with the diffraction and radiation of the floating body,and the wave force on the floating body will change.