# Impingement of deposited water nanodroplets with coming nanoparticles: A molecular dynamics study

## TL;DR

This paper uses simulations to study how nanoparticles can quickly remove water droplets from surfaces, which could help in surface hydrophobicity recovery.

## Contribution

The study introduces a molecular dynamics approach to investigate nanoparticle impact on water droplets and maps phase diagrams for different conditions.

## Key findings

- Nanoparticles can cause deposited water droplets to bounce or separate based on their velocity and size.
- Phase diagrams reveal how kinetic energy, nanoparticle size, and surface wettability influence droplet behavior.
- The mechanisms of droplet removal involve kinetic and surface energy changes captured through simulations.

## Abstract

Nowadays, the manipulation of water droplets has received growing interest in both academia and industry. In the current work, we aim to induce a quick sweep of deposited water droplets upon surfaces using impact nanoparticles. With the help of molecular dynamics (MD) simulations, we observe the dynamic evolution of targeted systems under different conditions. For a small value of particle’s size, deposition, wrapped bounce, and separated bounce take place as a progressive increase in particle’s velocity. The motion of a particle can be directly captured through obscuring water molecules. Moreover, the mechanisms underlying these different dynamic evolutions have been revealed through calculating kinetic energy, surface energy, and observing snapshots. In addition, we map two phase diagrams with respect to the dimensionless input kinetic energy (Ek, dim), the diameter of the nanoparticle to that of the water droplet (Δ), and the intrinsic wettability of the surface (θsur) to overall investigate these effects and observe all the possible outcomes. This work paves the way to understanding the progress of impingement of nanoparticles on deposited water droplets upon surfaces, which may be a good candidate for rapidly removing deposited water droplets and recovering the hydrophobicity of solid surfaces.