Head-on Collision of Two Nanodroplets on a Solid Surface: A Molecular Dynamics Simulation Study

Area of Science:

• Fluid Dynamics
• Surface Science
• Nanotechnology

Background:

• Most research examines single droplet impacts.
• Real-world scenarios involve multiple droplet collisions.
• Understanding nanodroplet interactions on surfaces is crucial.

Purpose of the Study:

• Investigate the head-on collision of two nanodroplets on a solid surface.
• Analyze the influence of impact velocity, surface interaction intensity, and surface solid fraction.
• Develop a theoretical model for predicting droplet spreading.

Main Methods:

• Molecular dynamics simulations were employed.
• Independent simulation cases were run to isolate variables.
• Key metrics like maximum spreading factor and dimensionless spreading time were quantified.

Main Results:

• Maximum spreading factor is more sensitive to surface solid fraction than interaction intensity.
• Dimensionless spreading time exhibits a complex dependency on interaction intensity, decreasing then increasing.
• Higher impact velocity and increasing solid fraction enhance spreading.
• Wetting states (Wenzel to Cassie) influence spreading dynamics.

Conclusions:

• Surface properties, including initial and final wetting states, critically affect nanodroplet collision outcomes.
• A validated theoretical model for maximum spreading factor on smooth surfaces was developed.
• This research enhances the understanding of multi-nanodroplet collisions on solid surfaces.