Numerical solution of phase field models for two-phase flows

Phase-field models describe the motion of multiphase flows using smooth interfaces across which the composition changes continuously. The phase-field variable represents a measure of phase as it quantifies relative differences or fractions of the fluid s components. The Cahn-Hilliard equation was originally proposed to model spinodal decomposition and coarsening in binary alloys. To this day, it has become broad ranged in its applicability. This thesis focuses on solving the Cahn-Hilliard equation numerically. A review of the mathematical modelling is made in order to develop numerical methods. Different numerical simulations in two dimensions are implemented to study the numerical and physical properties. Two realistic physical examples are also numerically solved

A multiphase Cahn-Hilliard system with mobilities and the numerical simulation of dewetting

We propose in this paper a new multiphase Cahn-Hilliard model with doubly degenerate mobilities. We prove by a formal asymptotic analysis that it approximates with second order accuracy the multiphase surface diffusion flow with mobility coefficients and surface tensions. To illustrate that it lends itself well to numerical approximation, we propose a simple and effective numerical scheme together with a very compact Matlab implementation. We provide the results of various numerical experiments to show the influence of mobility and surface tension coefficients. Thanks to its second order accuracy and its good suitability for numerical implementation, our model is very handy for tackling notably difficult surface diffusion problems. In particular, we show that it can be used very effectively to simulate numerically the dewetting of thin liquid tubes on arbitrary solid supports without requiring nonlinear boundary conditions.Comment: 35 page