Journal ArticleDOI
Enhanced stability of free viscous films due to surface viscosity
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In this paper, the stability of a thin liquid film bounded by two free surfaces is examined in the presence of insoluble surface-active agents, and it is shown that rupture can be significantly delayed with high surface viscosity.Abstract:
The stability of a thin liquid film bounded by two free surfaces is examined in the presence of insoluble surface-active agents. This study is broadly aimed at understanding enhanced stability of emulsions with the increasing surface concentration of surface-active agents. Surface-active agents not only cause gradients in surface tension but could also render surface viscosity to be significant, which could vary with surface concentration. We employ two phenomenological models for surface viscosity, a linear viscosity model and a nonlinear viscosity model. In the latter, surface viscosity diverges at a critical concentration, which is termed the “jamming” limit. We show that rupture can be significantly delayed with high surface viscosity. An analysis of the “jamming” limit reveals that Γi(nl)>3D/M provides a simple criterion for enhanced stability, where Γi(nl), D, and M are the normalized initial surfactant concentration, disjoining pressure number, and Marangoni number, respectively. Nonlinear simulations suggest that high surface viscosity renders free films remarkably stable in the jamming limit, and their free surfaces behave like immobile interfaces consistent with experimental observations. Furthermore, it is shown that rupture times can be arbitrarily increased by tuning the initial surfactant concentration, offering a fluid dynamical route to stabilization of thin films.read more
Citations
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The effect of wall slip on the dewetting of ultrathin films on solid substrates: Linear instability and second-order lubrication theory
TL;DR: In this article, the influence of wall slip on the instability of a nonwetting liquid film placed on a solid substrate is analyzed in the limit of negligible inertia, and a parabolic model is developed to accurately predict the linear dynamics of the film for arbitrary slip lengths.
Journal ArticleDOI
The effect of wall slip on the dewetting of ultrathin films on solid substrates: Linear instability and second-order lubrication theory
TL;DR: In this article, the influence of wall slip on the instability of a nonwetting liquid film placed on a solid substrate is analyzed in the limit of negligible inertia, and a parabolic model is developed to accurately predict the linear dynamics of the film for arbitrary slip lengths.
Journal ArticleDOI
Effect of insoluble surfactants on a thermocapillary flow
Franco Nicolas Pinan Basualdo,Franco Nicolas Pinan Basualdo,R. Terrazas Mallea,Benoit Scheid,Aude Bolopion,Michaël Gauthier,Pierre Lambert +6 more
TL;DR: In this article, the thermocapillary flow is induced at the air-water interface by locally heating it with an infrared laser, setup that is used to manipulate floating particles through the generated flow.
Journal ArticleDOI
Axisymmetric bare freestanding films of highly viscous liquids: Preparation and real-time investigation of capillary leveling.
Vincenzo Ferraro,Massimiliano M. Villone,Volodymyr Tkachenko,Lisa Miccio,Lorenzo Lombardi,Daniele Tammaro,Ernesto Di Maio,Gaetano D'Avino,Pier Luca Maffettone +8 more
TL;DR: In this paper, the authors developed an opto-mechanical tool to perform and study the preparation and the capillary leveling flow of axisymmetric bare freestanding liquid films.
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Influence of calcium chloride in coal on guar-based foam fracturing fluid rheological property: an experimental study
TL;DR: In this article , the influence of CaCl2 in coal seams on rheological property of foam fracturing fluid, the guar powder was used as a foam stabilizer, the anionic and cationic surfactants were used as foaming agents.
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