An interface-compressed diffuse interface method and its application for multiphase flows

Abstract

In this paper, an interface-compressed diffuse interface method is proposed for simulating multiphase flow with a large density ratio. In this method, an interface-compression term is introduced into the Cahn-Hilliard equation to suppress the interface dispersion caused by the numerical and modeling diffusion. The additional term only takes effect in the region of phase interface and works normal to the interface. The compression rate can be adjusted synchronously according to the local gradient of normal velocity at the interface. Numerical validations of the proposed method are implemented by simulating Rayleigh-Taylor instability, bubble deformation in shear flow, bubble merging, and bubble rising with a density ratio of 1000 and a viscosity ratio of 100. Good agreement of interface shapes and flow properties has been achieved as compared with both analytical solutions and published data in the literature. The obtained results also show that the present method makes great improvement of interface sharpness and avoids the occurrence of unphysical phenomenon. Meanwhile, the tiny interfacial structures can be captured effectively.