NUMERICAL SIMULATION OF CONTACT LINE PROBLEMS USING PHASE FIELD MODEL

Abstract

In this thesis, efficient numerical methods are developed to simulate the vapor-liquid system in a rectangle or a cube using the phase field model. When no gravity is considered and the walls are hydrophobic with no-slip boundary condition imposed on all walls, the initial random noise vapor- liquid system will evolve to a stable droplet at the center and the velocity field of the droplet will tend to zero at equilibrium. With the same boundary conditions, the initial system with water on the one side and vapor on the other side will also evolve to a stable droplet at the center. While all walls are hydrophilic, a stable bubble will be formulated at the center and the water will be attracted to the walls when no-slip boundary condition is imposed on all walls. A lot of numerical experiments are done to verify the relation between the static contact angle and the wettability of the flat solid substrate derived from the Young?s relation by Borcia. Numerical experiments are carried out to simulate the droplet sliding on the inclined substrate when microgravity is imposed. The numerical results reveal that the final stable velocity of the droplet sliding on the inclined substrate linearly depends on the microgravity imposed.