Issue 37, 2018

The air entrapment under a drop impacting on a nano-rough surface

Abstract

We study the impact of drops onto a flat surface with a nano-particle-based superhydrophobic coating, focusing on the earliest contact using 200 ns time-resolution. A central air-disc is entrapped when the drop impacts the surface, and when the roughness is appropriately accounted for, the height and radial extent of the air-disc follow the scaling laws established for impacts onto smooth surfaces. The roughness also modifies the first contact of the drop around the central air-disc, producing a thick band of micro-bubbles. The initial bubbles within this band coalesce and grow in size. We also infer the presence of an air-film residing inside the microstructure, at radial distances outside the central air-disc. This is manifest by the sudden appearance of microbubbles within a few microseconds after impact. The central air-disc remains pinned on the roughness, unless it is chemically altered to make it superhydrophilic.

Graphical abstract: The air entrapment under a drop impacting on a nano-rough surface

Supplementary files

Article information

Article type
Paper
Submitted
24 May 2018
Accepted
22 Jul 2018
First published
02 Aug 2018
This article is Open Access
Creative Commons BY license

Soft Matter, 2018,14, 7586-7596

The air entrapment under a drop impacting on a nano-rough surface

K. R. Langley, E. Q. Li, I. U. Vakarelski and S. T. Thoroddsen, Soft Matter, 2018, 14, 7586 DOI: 10.1039/C8SM01070F

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements