Size Effect on Nano-Droplet Spreading on Solid Surface

MD simulations have been performed to study the behavior of nano-sized droplets impacting on a solid surface. Three droplet sizes of 6, 9 and 12 nm have been examined. The dynamic contact angle and the droplet maximum spreading rate were analyzed according to the droplet size and the nature of the substrate. The surface properties were varied from wettable to partially wet and non-wettable surfaces. It is found the dynamic contact angle changes significantly as the droplet size changed. While the equilibrium contact angle is less affected by change in the drop size. The wetting radius is increased by increasing the drop diameter for all kind of surfaces. We have observed the wetting radius varys with drop size according to a power law, with the power of nearly 0.5. The dynamic contact angle is affected by size with the same power of 0.5. For partially wet and non-wettable surfaces, there was observed a shift in time that delays the process of wetting with the power of 2/3 with drop size.