Liquid film rupture beyond the thin-film equation: a multi-component lattice Boltzmann study

Fuente: arXiv
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Autori principali: Pelusi, Francesca, Sega, Marcello, Harting, Jens
Natura: Preprint
Pubblicazione: 2022
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author Pelusi, Francesca
Sega, Marcello
Harting, Jens
author_facet Pelusi, Francesca
Sega, Marcello
Harting, Jens
contents Under the condition of partial surface wettability, thin liquid films can be destabilized by small perturbations and rupture into droplets. As successfully predicted by the thin film equation (TFE), the rupture dynamics are dictated by the liquid-solid interaction. The theory describes the latter using the disjoining pressure or, equivalently, the contact angle. The introduction of a secondary fluid can lead to a richer phenomenology thanks to the presence of different fluid/surface interaction energies but has so far not been investigated. In this work, we study the rupture of liquid films with different heights immersed in a secondary fluid using a multi-component lattice Boltzmann (LB) approach. We investigate a wide range of surface interaction energies, equilibrium contact angles, and film thicknesses. We found that the rupture time can differ by about one order of magnitude for identical equilibrium contact angles but different surface free energies. Interestingly, the TFE describes the observed breakup dynamics qualitatively well, up to equilibrium contact angles as large as 130$^\circ$. A small film thickness is a much stricter requirement for the validity of the TFE, and agreement with LB results is found only for ratios $ε=h/L$ of the film height $h$ and lateral system size $L$ such as $ε\lesssim\times10^{-3}$.
format Preprint
id arxiv_https___arxiv_org_abs_2203_13717
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Liquid film rupture beyond the thin-film equation: a multi-component lattice Boltzmann study
Pelusi, Francesca
Sega, Marcello
Harting, Jens
Fluid Dynamics
Under the condition of partial surface wettability, thin liquid films can be destabilized by small perturbations and rupture into droplets. As successfully predicted by the thin film equation (TFE), the rupture dynamics are dictated by the liquid-solid interaction. The theory describes the latter using the disjoining pressure or, equivalently, the contact angle. The introduction of a secondary fluid can lead to a richer phenomenology thanks to the presence of different fluid/surface interaction energies but has so far not been investigated. In this work, we study the rupture of liquid films with different heights immersed in a secondary fluid using a multi-component lattice Boltzmann (LB) approach. We investigate a wide range of surface interaction energies, equilibrium contact angles, and film thicknesses. We found that the rupture time can differ by about one order of magnitude for identical equilibrium contact angles but different surface free energies. Interestingly, the TFE describes the observed breakup dynamics qualitatively well, up to equilibrium contact angles as large as 130$^\circ$. A small film thickness is a much stricter requirement for the validity of the TFE, and agreement with LB results is found only for ratios $ε=h/L$ of the film height $h$ and lateral system size $L$ such as $ε\lesssim\times10^{-3}$.
title Liquid film rupture beyond the thin-film equation: a multi-component lattice Boltzmann study
topic Fluid Dynamics
url https://arxiv.org/abs/2203.13717