Numerical Simulation of Larger Bubble Rising Process Based on Diffusion Interface Method

Based on the diffusion interface method and the finite element method, the shape and velocity of the larger bubble during the rising process were simulated. The results agree well with the experiments of the references. It is indicated that the diffusion interface method can correctly simulate the motion characteristics of the bubble. By using this model, the shape, velocity and oscillation of bubbles with different initial diameters were analyzed during the rising process. Moreover, the variations of shape and velocity of the bubble with diameter of 14 mm in rising process with different sizes of channel were also studied. The results show that with the increase of the initial diameter it takes more time to get the stable shape of the bubble from the ellipsoid to the spherical cap type. The larger the initial diameter bubble is, the greater the top velocity of the bubble is. The bottom velocity of the bubble increases rapidly at very beginning so that the bottom of the bubble is inward depression, then the bottom velocity falls back and shocks around the top velocity of the bubble. As the bubble rises in a smaller size channel, the top velocity of the bubble decreases, the height/width ratio increases and longer time is needed to get the stable shape.