Dewetting versus Rayleigh Instability inside Capillaries

Abstract

We study the dewetting of liquid films deposited inside nonwettable and wettable capillaries. Two processes compete: (i) Rayleigh instability (i.e., amplification of thickness fluctuations) and (ii) dewetting by nucleation and growth of a dry zone limited by a rim collecting the liquid. At times shorter than the characteristic time τM of the growth of the Rayleigh instability, we expect two regimes: (i) annular rims and drying at constant velocities and (ii) columnar rims with drying velocities decreasing versus time. For wettable capillaries, in a certain regime of thin thicknesses, the Rayleigh instability is absent and dewetting is the only process to remove the film.

The dynamics of capillary-driven two-phase flow: The role of nanofluid structural forces

“…Callegari et al [39] developed a theoretical model describing the annular rim moving velocity inside the nonwettable capillary (liquid does not ''like'' to wet). In their paper, the rim velocity they derived is given in Eq.…”

“…Commonly, discussions in the literature concerning the stability of a film wetting a capillary consider the role of the capillary pressure that drives the film to thin [29,30,[39][40][41][42][43]. The wetting film in this study is an oil film and is in contact with an oily meniscus with a concave shape.…”

Suppression of Dewetting in Pulsed Laser Melting of Thin Metallic Films on SiO2

“…As the layer configuration is changed, longrange interactions between the layers [11] may overlap, and so the complete layer stack must be considered when determining the driving forces. These overlapping contributions diminish when the layer thickness increases above 100 nm [12].…”

A Study of Dewetting on (001) Rutile using AFM

“…[4] Films dewet to minimize the liquid/vapor interface area. [5] When a substrate coated with a surface film is at a higher temperature than the surrounding atmosphere the Rayleigh instability results. [6] The thickness variations cause the film to break apart into droplets.…”

“…[5] For thicker films on a planar substrate, dewetting via the Rayleigh instability occurs more slowly. [5] Plasma-enhanced chemical-vapor deposition (PECVD) was performed with a SiH 4 precursor pumped into the chamber at 200 standard cc/min (sccm) and N 2 O pumped at 400 sccm. Chamber pressure was 900 mTorr and 20 W of power was used to drive the deposition.…”