Numerical study of multiphase droplet dynamics and contact angles by smoothed particle hydrodynamics

In this paper, an efficient method is developed for droplet simulation with high density ratios using smoothed particle hydrodynamics (SPH). The new approach is straightforward compared to previous studies and is applied to both static and dynamic droplet problems. Regarding the continuum surface force method which needs the normal vector and surface curvature in surface tension calculation, a color function formulation is introduced for tracking and correcting color function of boundary particles. This leads to a stable and accurate droplet simulation which reflects the reality of surface-tension force and droplet profile without the need for setting the desired unit normal vectors directly. The developed model is validated for droplet oscillation, static contact angles, liquid droplet evolution, dynamic wetting angles on inclined surfaces and droplets collision. The results demonstrates that the developed formulation can capture the equilibrium contact angle and handle droplets motion over inclined surfaces with different inclination angles and gravitational accelerations accurately.