3-D Analysis Of Diffraction-wave To Semi-submersible Platform In Time Domain

Three-dimensional boundary element method is introduced in this paper to analyse and compute the force of diffraction wave around semi-submersible platform in Time Domain.Creat model with Gambit software and export the data of mesh node,change the fomat of data in order to accord with Potential Flow Theory.The artificial boundary condition which is based on the multi-transimitting formula is applied to simulate the radiation condition.A stable Integration form of Free surface Boundary Condition is used to update velocity potention of free surface.Theoty of Mirror Phase is applied to simulate the undersde condition. The majoy work is as follows:1.A numerical model is presented to solve the problem of regular and irregular wave diffraction around a 3D vertical circular cylinder in chapter 2.The numerical results agree with the theoretical results well. Some parameters such as time step,panel size,artificial-velocity of waves,the distance and shape of the artificial boundary surface etc.are studied to get the steady results.?Since the irregular waves problems in hydrodynamics are diffieult to solve in some usual methods,this new method may help to solve these problems in an altemative way.2.Analyse and compute the problem of waves diffraction around a single vertical truncated circular cylinder in chapter 3. The numerical results agree with the experimental results and the results of high order panal method well. Another numerical model is presented to solve the problem of regular and irregular wave diffraction around four vertical truncated circular cylinders. Some parameters such as the distance between cylinders, the angle of the direction of wave and the ratio of the height of the truncated circular cylinder and the water depth etc.are studied to get their influence to the wave force.Show the pictures of regular and irregula wave shape and the spectrum pictures of wave forces.Comput the wave force of vertical rectangular cylinders in brief.3.Given the reality in project,a simplified model of semi-submersible platform is presented to compute the diffracted wave force under different wave angle and irregular waves conditions.At last show the pictures of incident,diffracted and the whole irregular wave shape and the spectrum pictures of wave forces.