A numerical study of droplet impact on solid spheres: The effect of surface wettability, sphere size, and initial impact velocity

Abstract

The present work numerically studies the dynamics of a droplet impact on solid spheres with different sizes and surface wettability. Different initial impact velocities are also set to the droplet to consider the velocity effect. A particle-based numerical method, many-body dissipative particle dynamics (MDPD), is employed to perform the simulations. The simulation results show that the post-impact droplet morphology highly depends on the impact velocity, size and surface wettability of solid spheres. At lower impact velocities, the droplet can sit on the top of the solid surfaces and keep a semi-sphere shape; while at higher impact velocities, for smaller solid spheres, the droplet can fully wrap the spheres and even drip off. For impact on larger spheres, on the hydrophilic surfaces, the final stable liquid film thickness is highly velocity-dependent, while on the hydrophobic surfaces, the droplet always sits on top of the sphere with the same liquid thickness.