Numerical Research On Bubble Merging And Its Motion In Shear Flow

the dynamic performance of bubble has attracted scholars due to the widely application in the chemical industry,environment and all aspects of life.The paper reports the numerical calculation of the merging of two bubbles and the deformation of single bubble in shear flow using the LBM method based on free energy model.The main work and conclusions are as follows:(1)The equilibrium distribution functions for the lattice model of D3Q15 have been established,which are verified by the Laplace law and the analytical solution for gas-liquid interface profile.Results show that the pressure jump across the interface has linear relation with the surface tension force,as the Laplace law states.(2)The merging of two bubbles has been studied in two dimensions as well as in three dimensions.Results show that the merging of two bubbles not only depends on the initial distance,but also depends on the surface tension.The larger the surface tension is,the greater the critical distance for the mergence of bubbles is.In addition,the merging velocity has also been studied.It has been found that the velocity of bubble merging is decaying to zero with damping oscillations.Besides,results show that in the process of bubbles merging,the velocity peak and the time required to reach the peak of the velocity have the power law relations with the surface tension,respectively.(3)The bubble deformation in shear flow in three dimensions has been studied.It has been shown that the main axis of the bubble is always stretched while the mean axis and minor axis are compressed when the bubble is subjected to shear flow.Furthermore,when the Ca number or the gas-to-fluid viscosity ratio increases,the deformation and deflection of bubble are both significant.