Dynamics of sliding drops on superhydrophobic surfaces

TL;DR

This study uses a lattice Boltzmann simulation to explore how drops slide on superhydrophobic surfaces with regular post arrays, revealing how post density and contact angle influence drop velocity.

Contribution

It introduces a numerical approach to analyze drop dynamics on patterned superhydrophobic surfaces, highlighting the effects of post density and contact angle on sliding behavior.

Findings

Drop velocity increases as post density decreases for suspended drops.

Contact angle depends on the area covered by posts.

Collapsed drops exhibit decreased velocity with increased post density.

Abstract

We use a free energy lattice Boltzmann approach to investigate numerically the dynamics of drops moving across superhydrophobic surfaces. The surfaces comprise a regular array of posts small compared to the drop size. For drops suspended on the posts the velocity increases as the number of posts decreases. We show that this is because the velocity is primarily determined by the contact angle which, in turn, depends on the area covered by posts. Collapsed drops, which fill the interstices between the posts, behave in a very different way. The posts now impede the drop behaviour and the velocity falls as their density increases.