Numerical Simulation of Gravity-Driven Droplet Displacement on an Inclined Micro-Grooved Surface

Gravity-driven displacement of droplet on an inclined micro-grooved surface is studied using Pseudo-potential model of lattice Boltzmann method. To validate the numerical method, we find good agreement of the LB simulations with the pressure difference by Laplace’s law. The equilibrium contact angle of a droplet wetting on a smooth horizontal surface is studied as a function of the wettability, finding good agreement with an empirical scheme obtained with Young’s equation. The dynamic behavior of a droplet wetting on micro-grooved horizontal surface is found to be complex and greatly affected by the fraction of the grooved area and the groove width, the results indicate that the effect of grooves on contact angle is dependent on the fraction of the grooved area and the groove width has not a consistent effect on contact angles. For an inclined nonwetting micro-grooved surface, in given range, higher fraction of the grooved area and smaller groove width lead to greater benefit for droplet sliding down. What’s more, the results indicate that higher gravity value leads to a higher decrease of movement resistance of the droplet by decreasing the contact area between the droplet and solid surface.