Thin film modelling of magnetic soap films
File(s)
Published version
Author(s)
Lalli, Navraj S
Giusti, Andrea
Type
Journal Article
Abstract
Magnetic soap films under the forcing of an inhomogeneous magnetic field are governed by a wide range of interconnected physics. The study of magnetic soap films requires the development of comprehensive models to support experimental observations. In this study, the thin film approximation is applied to the Navier–Stokes equations to derive a model for the film thickness of magnetic soap films that incorporates the effects of interfacial mobility, surfactant transport and magnetite nanoparticle (NP) transport. This derived model consists of a coupled system of equations for the film thickness, interfacial velocity, interfacial surfactant concentration and magnetite NP concentration. Simulations are performed for both soap films and magnetic soap films by solving the system of equations using the Galerkin finite element method, and results are compared with experiments. Simulation results highlight that interfacial flows can dominate the rate of film thinning and that accounting for the dependence of the magnetisation on the local magnetite NP concentration can influence the predicted speed of magnetically driven flows. Furthermore, simulation results demonstrate that the model is able to predict marginal regeneration in qualitative agreement with the experiments for soap films; the model also predicts the same flow pattern as seen in the experiments for magnetic soap films. Overall, this study advances the state of soap film and magnetic soap film modelling and will contribute to acquiring control over the drainage and stability of magnetic soap films in the long term.
Date Issued
2024-05-10
Date Acceptance
2024-03-29
Citation
Journal of Fluid Mechanics, 2024, 986
ISSN
0022-1120
Publisher
Cambridge University Press (CUP)
Journal / Book Title
Journal of Fluid Mechanics
Volume
986
Copyright Statement
© The Author(s), 2024. Published by Cambridge University Press. This is an Open Access article,
distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/
licenses/by/4.0), which permits unrestricted re-use, distribution and reproduction, provided the original
article is properly cited.
distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/
licenses/by/4.0), which permits unrestricted re-use, distribution and reproduction, provided the original
article is properly cited.
License URL
Identifier
http://dx.doi.org/10.1017/jfm.2024.335
Publication Status
Published
Article Number
A7
Date Publish Online
2024-04-30