Abstract: In the framework of diffuse interface method (DIM), an efficient hybrid method for muhiphase flows with large density ratios is proposed. Lattice Boltzmann method is employed to obtain information of flow field. Cahn-Hilliard (C-H) equation is directly solved to identify the interface. In order to maintain stabihty of calculation at large density ratios, convection term of C-H equation is discretized by using second order unwind scheme. Numerical simulations of Rayleigb-Taylor (R-T) instability, bubble rising in liquid and droplet impact on a dry surface are implemented. The results agree well with data in literature.

Key words: diffuse interface method, lattice Boltzmann equation, Cahn-Hilliard, large density ratio