Study On The Multiphase Flow Interface Simulation Based On SPH Method

As an important branch of computer graphics,fluid simulation has been widely used in such as film and television special effects,video games,animation and medical imaging,and multiphase flow simulation is an important research direction of fluid simulation.In multiphase flow simulation,it is important and difficult to solve the problem of interface stability,the surface tension of two-phase flow(such as gas-liquid two-phase flow)interface with large density ratio,and how to improve the efficiency of the search method.The related research not only has some theoretical significance,but also has strong practical application value.This thesis first introduces the background,significance,history and research status at home and abroad on the interface pressure treatment of immiscible two-phase flow,the surface tension of two-phase flow with high density ratio and adjacent particle search,and then does the following three aspects of work according to the above three problems.1.The traditional SPH method is used to simulate the immiscible two-phase flow(such as water and oil).Due to the severe numerical oscillation at the interface of two-phase flow,the interface is rough,unsmooth and heterogeneous particles are trapped.To solve this problem,this paper proposes an improved pressure gradient formula and artificial repulsion formula;through the dam break simulation experiment,Rayleigh Taylor interface instability simulation experiment and non Boussinesq lock-in exchange simulation experiment,the simulation results verify the effectiveness of the new pressure gradient formula and artificial repulsion formula.2.The traditional SPH method is used to simulate the interface surface tension of two-phase flow with large density ratio(such as gas-liquid two-phase flow)and large curvature.Due to the color gradient jump in the calculation of color function,the interface details are missing and the interface is rough.In order to solve this problem,a color function calculation formula based on density weight is proposed in this paper The results show that the proposed method is effective.3.In multiphase flow simulation,neighbor particle search is time-consuming,and how to improve the efficiency of neighbor particle search in multiphase flow simulation is less studied.This paper makes a preliminary exploration in this aspect: firstly,the direct search method,tree search method and strip PIB search method are comprehensively sorted out,and the time-consuming and accuracy of the above three algorithms are compared through the two-dimensional dam break experiment of single-phase flow;then the multiphase flow collision experiment is carried out to find the most efficient multiphase flow The simulated neighbor particle search algorithm lays a foundation for further optimization of multiphase flow simulation neighbor particle search in the future.