Abstract
In this thesis, a 3D lattice Boltzmann multiphase fluid model based on D3Q19 which is capable of dealing two phase flow with large density ratio and partial wetting surface with a given contact angle is investigated. Multiphase fluid behavior can be simulated using the Navier-Stokes equation coupling with convective Cahn-Hilliard equation [35], where the latter equation is used to capture the interface of multiphase fluid in terms of chemical potential. By adopting the free-energy model and adding an additional term into the total free energy to describe surface energy, a droplet rests on a surface with given contact angle can be simulated. The capability of the present model, which is to compute two phase flow with wettability controllable surface, is validated by simulating a droplet that rests on a surface with given contact angle. The contact angles calculated from the results agree with theory. The effect of gravitational force on droplet shape is also discussed in terms of Bond number. The present model is applied to simulate liquid lens cases. The simulation result shows good compatibility with the experiment done by Hsieh et al. [70], where Bond number is about 1.3.