Dynamic behavior of water droplets impacting on the superhydrophobic surface: Both experimental study and molecular dynamics simulation study

Abstract

Dynamic behavior of water droplets is an important feature in the study of wettability of solid surfaces. Here, molecular dynamics (MD) simulation was used to fabricate a three-dimensional physical model of a nanodroplet on a superhydrophobic nano-pillared surface that has same contact angle and sliding angle as the fabricated superhydrophobic surface with dandelion-like structures. Accordingly, we fabricated the relationship between the macro-scale experimental work and the nanoscale MD simulation work according to Weber number to study dynamics of water droplets impacting on the superhydrophobic surface. Based on experimental and MD simulation results, we find that dynamics of water droplets impacting on the superhydrophobic surface can be subdivided into spreading section and retraction section. We also used experiments and MD simulations to investigate the relationship between contact time and impact velocity, and found that the impact velocity has no influence on the contact time. Furthermore, the relationship between contact time, as well as restitution coefficient, and impact velocity (or Weber number) was characterized. All the trends we see from MD simulations are consistent with experiments. Therefore, the combined experiment and simulation provide an integrated study of the dynamics of droplets impacting on solid surfaces.