Influence of Liquid Viscosity on Droplet Impingement on Superhydrophobic Surfaces

TL;DR

This study investigates how varying liquid viscosity affects droplet impact behavior on superhydrophobic surfaces, revealing changes in jet formation and splashing phenomena across different Weber numbers.

Contribution

It provides new insights into the influence of liquid viscosity on droplet impingement dynamics on superhydrophobic surfaces, including jet suppression and splash delay.

Findings

Thin coherent jets occur at Weber numbers 5-15 for water.

Peripheral splashing happens above Weber number 200 for water.

Increased viscosity suppresses jets and delays splashing, with two-pronged jets observed in glycerol-water droplets.

Abstract

This fluid dynamics video describes droplet impingement experiments performed on superhydrophobic surfaces. When droplets of pure water are impinged upon superhydrophobic surfaces, a region of thin coherent jets are observed for Weber numbers between 5 and 15. Also, peripheral splashing is observed for Weber numbers above about 200. When the viscosity of the droplet is increased by mixing glycerol with the water, the thin jets are not observed and peripheral splashing is delayed somewhat. In the Weber number range where pure water droplets are observed to splash peripherally, the water/glycerol droplets are observed to have two-pronged jets.