Study Of Fluid Boundary Treatment Based On SPH Method

As an important Branch of computer graphics,fluid simulation has been widely used in many fields such as special effects,military simulation,animation and medicine.The solid boundary and the free surface of the fluid both can be regarded as the boundary of the fluid.How to deal with the solid boundary of the fluid and the surface tension of the fluid quickly and accurately is an important subject in fluid simulation.Therefore,the study of the above problems has a strong practical value.This thesis first introduces the historical background and significance of fluid simulation boundary treatment and liquid surface tension research,as well as the history and present situation of related research at home and abroad.Then the following three aspects of work were carried out in response to the above problems.Because of the irregularity of free surface of fluid,the traditional ghost method has a large amount of calculation and is difficult to generate ghost particle field dynamically.In view of the above defects,an improved ghost particle method is proposed in this thesis.On the basis of treating the free surface well,the ghost field can be generated more easily,and the calculation amount will be greatly reduced.Image particle method in smooth particle hydrodynamics is an important method to deal with solid boundary.Image particle method deals with solid boundary problems by dynamically generating corresponding mirror particles outside the boundary by fluid particles near the boundary.However,with the improvement of the complexity of the boundary,the complexity of the traditional mirror particle method to generate the mirror particles is also increased,and the simulation efficiency is reduced.In order to solve the above problem,the mirror particle method is improved in this paper by giving a new technique for calculating values of mirror particle field,which effectively reduces the complexity of the generation of traditional mirror particles with complex boundary conditions,and the field of fluid particles near the boundary is more uniform.A lot of simulation results show that this method becomes more efficient compared with the mirror particle method with the increasement of the number of particles and the complexity of the scene.The treatment of liquid free surface based on smooth particle hydrodynamics(SPH)is a challenging problem.The main reason is that the liquid free surface tension is difficult to simulate and numerical instability caused by the boundary truncation due to particle deficiency at the gas-liquid interface.In this paper,a new liquid surface tension procession algorithm is constructed based on the IIF method,the traditional method of dealing with surface tension,combining the gas pressure method.Simulation results show that this method can accurately and stably simulate the free surface tension of liquid,the simulated liquid free surface is smoother and more realistic.In addition,a new kernel function is proposed to improve the simulation efficiency.