Lattice Boltzmann Method For The Simulation Of Two-phase Flow

Two-phase flow is a kind of widespread physical problem. If it’s flow pattern and flow behavior can be predicted accurately, it will be of great value to the work and life. But compared with the single phase flow, the force and motion in two-phase flow is quite complex, and affected by many factors, so the traditional method of using numerical simulation can’t handle it. The lattice Boltzmann method witch is a kind of mesoscopic method based on the theory of molecular motion is an effective new method for physical problems, In this paper, the research content derived from the national natural science fund project named "the numerical simulation research of viscoelastic fluid extrusion swelling and multiphase flow based on the lattice Boltzmann method " is raising a lattice Boltzmann model to simulate the two-phase fluid flow.In this paper, we study the effects of different parameters on the relaxation process and the fusion of the different parameters based on the lattice Boltzmann color model. Finding that the bigger Ak and γ and the smaller vr, the liquid drops are prone to shock, in the process of relaxation, and that Ak had the most significant effect on the evolution of equilibrium.And then on the basis of this model, the influence of gravity is added. The effects of different parameters on the motion and shape change, the influence of the movement of the droplet on the flow field, the relationship between the steady velocity and the initial radius of the droplet were numerically simulated. Finding that vr almost has no influence on the shape changes of droplet in floating process, but has great influence in sinking process. Different Ak and ρr not only has a great influence on the shape change of droplets in the floating the process, but also have a great impact on the speed. While in the sinking process, ρr has almost no influence on the shape change of droplets. In the process of the horizontal flow field Ak has a great influence on the shape change of the droplets.Owning to the conventional color model is not accurate in the simulation of a large density ration, this paper introduces two order, four order and six order isotropic color gradient, so the large density ratio of two-phase flow problem can be accurately simulated.On the different density ratio (γ=1,100,1000), the interfacial tension is simulated with four different color gradient under different Ak, and the error and causes is analyzed. On this basis, the different color gradient’s best applicable scope and appropriate parameter selection are given. All this can laid a certain foundation for further theoretical study.