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Surfactant effects on the dynamics of a thin liquid sheet

Published online by Cambridge University Press:  26 April 2006

Luigi De Luca  and
Carosena Meola
Luigi De Luca
Affiliation:
Politecnico di Torino, Department of Aerospace Engineering, Corso Duca degli Abruzzi, 24, 10129 Turin, Italy Present address: Università di Napoli, DETEC P.le Tecchio, 80, 80125 Naples, Italy.
Carosena Meola
Affiliation:
Politecnico di Torino, Department of Aerospace Engineering, Corso Duca degli Abruzzi, 24, 10129 Turin, Italy
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Abstract

The dynamics of a free-surface slender two-dimensional stream (liquid sheet) issuing from a nozzle in the gravitational field in still air, under the effect of surface-active agents, are analysed experimentally. The particular test section geometry (the liquid is forced to assume a bidimensional form between two vertical guides and a horizontal plate placed at a certain variable distance from the nozzle exit section) employed in this study gives rise to various flow regimes depending on the governing parameters: liquid flow rate, sheet height, surface pressure, gravity. Two basic phenomena are observed: thinning of the sheet (with recirculating motion inside it) and sheet-threadlines transition. For a certain surfactant (bulk) concentration, there exists a minimum critical flow rate value for which the sheet is seen to thin starting at both of the sheet bottom corners. A ridge, usually referred to as a Reynolds ridge in the literature, separates the sheet from the thin-film regions. The thin films exhibit recirculating flows (caused by the onset of surfactant-induced surface-pressure-driven convection in the gravitational field) and extend to the entire rectangular interface as the flow rate is reduced. At zero flow rate the thinned sheet resembles a plane vertical soap film showing a recirculating cellular structure. These phenomena are linked to the presence of surface-active material adsorbed at the liquid-air interface and occur when the sheet height exceeds a critical value. Otherwise, at a critical flow rate value the liquid sheet breaks up into an array of (more or less regularly distributed) discrete threadlines (vertical jets), whose spacing depends on the surface tension of the test liquid.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 300 , 10 October 1995 , pp. 71 - 85
Copyright
© 1995 Cambridge University Press

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References

Brown, D. R. 1961 A study of the behaviour of a thin sheet of moving liquid. J. Fluid Mech. 10, 297–305.Google Scholar
Carlomagno, G. M. 1974 Moto di un film liquido su un cilindro orizzontale posto in aria calma. Proc. II Congr. Naz. AIMETA, pp. 253–262.
Carlomagno, G. M. & luca, L. De 1987 Instability of a thin liquid sheet in the gravitational field. Proc. Intl Conf. Fluid Mech., Beijing, pp. 213–218. Peking University Press.
luca, L. De & Costa, M. 1995 Two-dimensional flow of a liquid sheet under gravity. Computers Fluids 24, 401–414.Google Scholar
Halpern, D. & Grotberg, J. B. 1992 Dynamics and transport of a localized soluble surfactant on a thin film. J. Fluid Mech. 237, 1–11.Google Scholar
Harper, J. F. 1992 The leading edge of an oil slick, soap film, or bubble stagnant cap in Stokes flow. J. Fluid Mech. 237, 23–32.Google Scholar
Ji, W. & Setterwall, F. 1994 On the instabilities of vertical falling liquid films in the presence of surface-active solute. J. Fluid Mech. 278, 297–323.Google Scholar
Koschmieder, E. L. & Prahl, S. A. 1990 Surface-tension-driven Bénard convection in small containers. J. Fluid Mech. 215, 571–583.Google Scholar
Lee, S. L. 1963 Taylor instability of a liquid film around a long, horizontal, circular cylindrical body in still air. Trans. ASME E: J. Appl. Mech. 85, 443–447.Google Scholar
Lerner, L. & Harper, J. F. 1991 Stokes flow past a pair of stagnant-cap bubbles. J. Fluid Mech. 232, 167–190.Google Scholar
Levich, V. G. 1962 Physicochemical Hydrodynamics Prentice Hall.
Limat, L., Jenffer, P., Dagens, B., Touron, E., Fermigier, M. & Wesfreid, J. E. 1992 Gravitational instabilities of thin liquid layers: dynamics of pattern selection. Physica D 61, 166–182.Google Scholar
Lin, S. P. 1981 Stability of a viscous liquid curtain. J. Fluid Mech. 104, 111–118.Google Scholar
Lin, S. P., Lian, Z. W. & Creighton, B. J. 1990 Absolute and convective instability of a liquid sheet. J. Fluid Mech. 220, 673–689.Google Scholar
Lin, S. P. & Roberts, G. 1981 Waves in a viscous liquid curtain. J. Fluid Mech. 112, 443–458.Google Scholar
Mctaggart, C. L. 1983 Convection driven by concentration- and temperature-dependent surface tension. J. Fluid Mech. 134, 301–310.Google Scholar
Pearson, J. R. A. 1958 On convection cells induced by surface tension. J. Fluid Mech. 4, 489–500.Google Scholar
Pritchard, W. G. 1986 Instability and chaotic behaviour in a free-surface flow. J. Fluid Mech. 165, 1–60.Google Scholar
Rosen, M. J. 1989 Surfactants and Interfacial Phenomena John Wiley & Sons.
Scott, J. C. 1982 Flow beneath a stagnant film on water: the Reynolds ridge. J. Fluid Mech. 116, 283–296.Google Scholar
Squire, H. B. 1953 Investigation of the instability of a moving liquid film. Brit. J. Appl. Phys. 4, 167–169.Google Scholar
Taylor, G. I. 1959 The dynamics of thin sheets of fluid - III. Disintegration of fluid sheets. Proc. R. Soc. Lond. A 253, 313–321.Google Scholar
Yih, C.-S. 1968 Fluid motion induced by surface-tension variation. Phys. Fluids 11, 477–480.Google Scholar