A Continuous Interface Model for the Direct Numerical Simulation of Phase-Change in Two-Component Liquid-Vapor Flows

This paper presents a model dedicated to the numerical simulation of two-component liquid-vapor flows with phase-change. This model is an extension to binary mixtures of the second gradient method, initially dedicated to pure fluids. It is a diffuse interface method: by assuming that the free energy of the mixture depends on its density gradient, liquid-vapor interfaces are described as volumetric transition regions across which physical properties vary continuously. The corresponding governing equations of the mixture are derived and the thermodynamic closure relation is established in order to recover the equilibrium properties of a mixture. As a first validation of this model, it is applied to study a one-dimensional isothermal phase-change problem. When the system reaches a stationary state, an asymptotic analysis shows that this model is in good agreement with sharp interface models, as well as numerical calculations.