Hostname: page-component-78c5997874-t5tsf Total loading time: 0 Render date: 2024-11-06T05:19:39.121Z Has data issue: false hasContentIssue false

On the thickness of soap films: an alternative to Frankel's law

Published online by Cambridge University Press:  25 April 2008

ERNST A. VAN NIEROP
Affiliation:
School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
BENOIT SCHEID
Affiliation:
School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
HOWARD A. STONE
Affiliation:
School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA

Abstract

The formation of soap films by vertical withdrawal from a bath is typically described by Frankel's law, which assumes rigid film ‘walls’ and shear-like dynamics. Since most soap films have interfaces that are not rigid, and as the flow in the withdrawal of thin free films is typically extensional, we reconsider the theory of soap film formation. By assuming extensional flow dominated by surface viscous stresses we find that the film thickness scales as the two-thirds power of the withdrawal speed U. This speed dependence is also predicted by Frankel's law; the difference lies in the origin of the viscous resistance which sets the pre-factor. When bulk viscous stresses are important the speed dependence can vary between U2/3 and U2.

Type
Papers
Copyright
Copyright © Cambridge University Press 2008

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Adelizzi, E. A. & Troian, S. M. 2004 Interfacial slip in entrained soap films containing associating hydrosoluble polymer. Langmuir 20, 74827492.CrossRefGoogle ScholarPubMed
Berg, S., Adelizzi, E. A. & Troian, S. M. 2005 Experimental study of entrainment and drainage flows in microscale soap films. Langmuir 21, 38673876.CrossRefGoogle ScholarPubMed
Braun, R. J. & King-Smith, P. E. 2007 Model problems for the tear film in a blink cycle: single-equation models. J. Fluid Mech. 586, 465490.CrossRefGoogle Scholar
Breward, C. J. W. 1999 The mathematics of foam. PhD thesis, Oxford University.Google Scholar
Breward, C. J. W. & Howell, P. D. 2002 The drainage of a foam lamella. J. Fluid Mech. 458, 379406.CrossRefGoogle Scholar
Bruinsma, R., di Meglio, J. M., Quéré, D. & Cohen-Addad, S. 1992 Formation of soap films from polymer solutions. Langmuir 8, 31613167.CrossRefGoogle Scholar
Cohen-Addad, S. & di Meglio, J.-M. 1994 Stabilization of aqueous foam by hydrosoluble polymers 2. Role of polymer/surfactant interactions. Langmuir 10, 773778.CrossRefGoogle Scholar
Durand, M. & Stone, H. A. 2006 Relaxation time of the topological T1 process in a two-dimensional foam. Phys. Rev. Lett. 97, 226101.CrossRefGoogle Scholar
Edwards, D. A., Brenner, H. & Wasan, D. T. 1991 Interfacial Transport Processes and Rheology. Butterworth-Heinemann.Google Scholar
Fruhner, H., Wantke, K.-D. & Lunkenheimer, K. 1999 Relationship between surface dilational properties and foam stability. Colloids Surfaces A 162, 193202.CrossRefGoogle Scholar
de Gennes, P. G., Brochard-Wyart, F. & Quéré, D. 2004 Capillarity and Wetting Phenomena: Drops, Bubbles, Pearls, Waves. Springer.CrossRefGoogle Scholar
Lal, J. & di Meglio, J.-M. 1994 Formation of soap films from insoluble surfactants. J. Colloid Interface Sci. 164, 506509.CrossRefGoogle Scholar
Lionti-Addad, S. & di Meglio, J.-M. 1992 Stabilization of aqueous foam by hydrosoluble polymers 1. Sodium dodecyl sulfate–poly(ethylene oxide) system. Langmuir 8, 324327.CrossRefGoogle Scholar
Liu, X. & Duncan, J. H. 2006 An experimental study of surfactant effects on spilling breakers. J. Fluid Mech. 567, 433455.CrossRefGoogle Scholar
Martin, B. & Wu, X.-I. 1995 Shear flow in a two-dimensional Couette cell: A technique for measuring the viscosity of free-standing liquid films. Rev. Sci. Instrum. 66, 56035608.CrossRefGoogle Scholar
Mysels, K. J. & Cox, M. C. 1962 An experimental test of Frankel's law of film thickness. J. Colloid Sci. 17, 136145.CrossRefGoogle Scholar
Mysels, K. J., Shinoda, K. & Frankel, S. 1959 Soap Films: Studies of Their Thinning. Pergamon.Google Scholar
Naire, S., Braun, R. J. & Snow, S. A. 2001 An insoluble surfactant model for a vertical draining free film with variable surface viscosity. Phys. Fluids 13, 24922502.CrossRefGoogle Scholar
Schwartz, L. W. & Roy, R. V. 1999 Modeling draining flow in mobile and immobile soap films. J. Colloid Interface Sci. 218, 309323.CrossRefGoogle ScholarPubMed
Scriven, L. E. 1960 Dynamics of a fluid interface: Equation of motion for Newtonian surface fluids. Chem. Engng Sci. 12, 98108.CrossRefGoogle Scholar
Shen, A. Q., Gleason, B., McKinley, G. H. & Stone, H. A. 2002 Fiber coating with surfactant solutions. Phys. Fluids 14, 4055.CrossRefGoogle Scholar