Droplets sliding on soft solids shed elastocapillary rails

Fuente: arXiv
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Autores principales: Xue, Nan, Wilen, Lawrence A., Style, Robert W., Dufresne, Eric R.
Formato: Preprint
Publicado: 2024
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author Xue, Nan
Wilen, Lawrence A.
Style, Robert W.
Dufresne, Eric R.
author_facet Xue, Nan
Wilen, Lawrence A.
Style, Robert W.
Dufresne, Eric R.
contents The surface tension of partially wetting droplets deforms soft substrates. These deformations are usually localized to a narrow region near the contact line, forming a so-called `elastocapillary ridge.' When a droplet slides along a substrate, the movement of the elastocapillary ridge dissipates energy in the substrate and slows the droplet down. Previous studies have analyzed isotropically spreading droplets and found that the advancing contact line `surfs' the elastocapillary ridge, with a velocity determined by a local balance of capillary forces and bulk rheology. Here, we experimentally explore the dynamics of a droplet sliding across soft substrates. At low velocities, the contact line is nearly circular, and dissipation increases logarithmically with speed. At higher droplet velocities, the contact line adopts a bullet-like shape, and the dissipation levels off. At the same time, droplets shed a pair of `elastocapillary rails' that fade away slowly behind it. These results suggest that droplets favor sliding along a stationary ridge over surfing atop a translating one.
format Preprint
id arxiv_https___arxiv_org_abs_2409_00280
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Droplets sliding on soft solids shed elastocapillary rails
Xue, Nan
Wilen, Lawrence A.
Style, Robert W.
Dufresne, Eric R.
Soft Condensed Matter
The surface tension of partially wetting droplets deforms soft substrates. These deformations are usually localized to a narrow region near the contact line, forming a so-called `elastocapillary ridge.' When a droplet slides along a substrate, the movement of the elastocapillary ridge dissipates energy in the substrate and slows the droplet down. Previous studies have analyzed isotropically spreading droplets and found that the advancing contact line `surfs' the elastocapillary ridge, with a velocity determined by a local balance of capillary forces and bulk rheology. Here, we experimentally explore the dynamics of a droplet sliding across soft substrates. At low velocities, the contact line is nearly circular, and dissipation increases logarithmically with speed. At higher droplet velocities, the contact line adopts a bullet-like shape, and the dissipation levels off. At the same time, droplets shed a pair of `elastocapillary rails' that fade away slowly behind it. These results suggest that droplets favor sliding along a stationary ridge over surfing atop a translating one.
title Droplets sliding on soft solids shed elastocapillary rails
topic Soft Condensed Matter
url https://arxiv.org/abs/2409.00280