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Instability of a non-wetting film with interfacial viscous stress

Published online by Cambridge University Press:  26 April 2006

David A. Edwards
Affiliation:
Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA Present address: David A. Edwards, Department of Chemical Engineering, 204 Fenske Laboratory, Penn State University, University Park, PA 16802, USA.
Alexander Oron
Affiliation:
Faculty of Mechanical Engineering and Center for Research in Nonlinear Phenomena, Technion-Israel Institute of Technology, Haifa, 32000 Israel

Abstract

The destabilization of a thin three-dimensional non-wetting film above a solid wall is examined for the special case in which surfactant is adsorbed onto the free surface of the film. Attention is restricted to the case of a Newtonian surface, with surfactant displaying rapid surface diffusion or exhibiting small Marangoni number, such that the dominant intrinsic interfacial stress is of a purely viscous origin. A surface-excess force approach is adopted for the purpose of incorporating into the analysis the attractive/repulsive dispersive forces acting between the solid wall and the film. Three coupled nonlinear partial differential equations are obtained that describe the ‘large-wavelength’ spatio-temporal evolution of the free film surface following a small initial disturbance. These equations are shown to reduce to results in the literature in the limit of zero interfacial viscosities. Employing linear stability analysis, an explicit dispersion equation is obtained relating the growth coefficient to interfacial viscosities. It is found, at least in the linear regime, that the sum of interfacial shear and dilatational viscosities – and not each separately – imparts a damping effect that in the most extreme case is four-fold relative to the case of no interfacial viscosities. Nonlinear stability analysis in the limiting case of a two-dimensional film indicates that interfacial viscosities may strongly hinder the onset of instability through large interfacial stresses that arise in the vicinity of trough and crest regions of the film.

Type
Research Article
Copyright
© 1995 Cambridge University Press

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References

Aris, R. 1962 Vectors, Tensors and the Basic Equations of Fluid Mechanics. Prentice Hall.
Boussinesq, M. J. 1913 Sur lcarexistance ď viscosité superficielle dans la mince couche de transition séparant un liquide ď autre fluide contigu. Ann. Chem. Phys. 29, 349357.Google Scholar
Burelbach, J. P., Bankoff, S. G. & Davis, S. H. 1988 Nonlinear stability of evaporating/condensing liquid films. J. Fluid Mech. 195, 463472.Google Scholar
Deryaguin, B. V. 1955 Definition of the concept of and magnitude of the disjoining pressure and its role in the statics and kinetics of thin layers of liquids. Colloid J. USSR 17, 191197.Google Scholar
Deryaguin, B. V. & Kusakov, M. M. 1937 Experimental study of solvation of surfaces as applied to the mathematical theory of the stability of lyophilic colloids. Akad. Nauk. SSSR, Khim. 6, 11191152.Google Scholar
Deryaguin, B. V. & Landau, L. 1941 Theory of the stability of strongly charged lyophobic sols and of the adhesion of strongly charged particles in solutions of electrolytes. Acta Physicochim. (USSR) 14, 633662Google Scholar
Edwards, D. A., Brenner, H. & Wasan, D. T. 1991 Interfacial Transport Processes and Rheology. Butterworth-Heineman.
Felderhof, B. U. 1968 Dynamics of free liquid films. J. Chem. Phys. 49, 4468.Google Scholar
Gennes, P. G. Hua, L. De & Levinson, P. 1990 Dynamics of wetting: local contact angles. J. Fluid Mech. 212, 5563.Google Scholar
Jain, R. K. & Ruckenstein, E. 1976 Stability of stagnant viscous films on a solid surface. J. Colloid Interface Sci. 54, 108116.Google Scholar
Jensen, O. E. & Grotberg, J. B. 1992 Insoluble surfactant spreading on a thin viscous film: shock evolution and rupture. J. Fluid Mech. 240, 259288.Google Scholar
Lucassen, J. & Hansen, R. S. 1966 Damping of waves on monolayer covered surfaces. I. Systems with negligible surface dilatational viscosity. J. Colloid Interface Sci. 22, 3244.Google Scholar
Maldarelli, C. & Jain, R. K. 1982 The linear, hydrodynamic stability of an interfacially perturbed, transversely isotropic, thin, planar viscoelastic film. I. General formulation and a derivation of the dispersion equation. J. Colloid Interface Sci. 90, 233261.Google Scholar
Maldarelli, C., Jain, R. K., Ivanov, I. & Ruckenstein, E. 1980 Stability of symmetric and unsymmetric thin liquid films to short and long wavelength perturbations. J. Colloid Interface Sci. 78, 118143.Google Scholar
Oron, A. & Edwards, D. A. 1993 Stability of a falling film in the presence of interfacial viscous stress. Phys. Fluids A 5, 506508.Google Scholar
Prieve, D. C. & Russel, W. B. 1988 Simplified predictions of Hamaker constants from Lifshitz theory. J. Colloid Interface Sci. 125, 113.Google Scholar
Ruckenstein, E. & Jain, R. K. 1974 Spontaneous rupture of thin liquid films. Chem. Soc. Faraday Trans. 270, 132137.Google Scholar
Salamon, T. R., Armstrong, R. C. & Brown, R. A. 1994 Traveling waves on vertical films: Numerical analysis using the finite element method. Phys. Fluids A 6, 22022220.Google Scholar
Sche, S. & Fijnaut, H. M. 1978 Dynamics of thin free liquid films stabilized with ionic surfactants. Surface Sci. 76, 186202.Google Scholar
Sharma, A. & Ruckenstein, E. 1986 An analytical nonlinear theory of thin film rupture and its application to wetting films. J. Colloid Interface Sci. 113, 456479.Google Scholar
Shaw, D. J. 19980 Introduction to Colloid and Surface Chemistry. Butterworths.
Silvey, A. 1916 The fall of mercury droplets in a viscous medium. Phys. Rev. 7, 106111.Google Scholar
Tan, M. J., Bankoff, S. G. & Davis, S. H. 1990 Steady thermocapillary flows of thin liquid layers. I. Theory. Phys. Fluids A 2, 313320.Google Scholar
Ting, L., Wasan, D. T. & Miyano, K. 1985 Longitudinal surface waves for the study of dynamic properties of surfactant systems II. Liquid-liquid interface. J. Colloid Interface Sci. 107, 345354.Google Scholar
Ting, L., Wasan, D. T., Miyano, K. & Xu, S. Q. 1984 Longitudinal surface waves for the study of dynamic properties of surfactant systems I. Gas-liquid interface. J. Colloid Interface Sci. 102, 248253.Google Scholar
Verwey, E. J. W. & Overbeek, J. T. G. 1948 Theory of the Stability ofLyophobic Colloids. Elsevier.
Whitaker, S. 1964 Effect of surface active agents on the stability of falling liquid films. Indust. Engng Chem. Fundam. 3, 132142.Google Scholar
Williams, M. B. & Davis, S. H. 1982 Nonlinear theory of film rupture. J. Colloid Interface Sci. 90, 220232.Google Scholar