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The electrohydrodynamic deformation of drops suspended in liquids in steady and oscillatory electric fields

Published online by Cambridge University Press:  26 April 2006

O. Vizika  and
D. A. Saville
O. Vizika
Affiliation:
Department of Chemical Engineering, Princeton University, Princeton, NJ 08544, USA
D. A. Saville
Affiliation:
Department of Chemical Engineering, Princeton University, Princeton, NJ 08544, USA
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Abstract

When an electric field is applied to a drop suspended in another liquid the drop deforms. The relation between the applied field and the mode and magnitude of the deformation have been studied extensively. Nevertheless, Torza, Cox & Mason (1971) found that quantitative agreement between the leaky dielectric theory (Taylor 1966) and experiment is quite poor. Here we describe results from a new series of experiments. Drops suspended in weakly conducting liquids were deformed into spheroids with both steady and oscillatory fields. Drop deformation, interfacial tension, and the electrical properties of the fluids were measured for each system to provide a definitive test of the theory. The agreement between the leaky dielectric model and our results for drop deformations in steady fields is much improved over previous results, although discrepancies remain for some systems. Drop deformations in oscillatory fields consist of steady and oscillatory parts because of the quadratic dependence on the field strength. Measurements of the steady part at 60 Hz, where the oscillatory deformation is negligible, are in excellent agreement with the theory. The effects of frequency on the steady deformation were studied by measuring oblate deformations at a series of frequencies and field strengths; the agreement with theory is good. Finally, the time-dependent total deformation was measured under conditions where both parts of the deformation are commensurate. Good agreement was found between the measured and predicted maximum and minimum deformations. Nevertheless, only a small range of fluid properties could be studied owing to the need to avoid droplet sedimentation.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 239 , June 1992 , pp. 1 - 21
Copyright
© 1992 Cambridge University Press

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References

Adamson, A. W.: 1967 Physical Chemistry of Surfaces, 2nd edn, Interscience.
Ajayi, O. O.: 1978 A note on Taylor's electrodynamic theory. Proc. R. Soc. Lond. A 364, 499–507.Google Scholar
Allan, R. S. & Mason, S. G., 1962 Particle behaviour in shear and electric fields. I. Deformation and burst of fluid drops. Proc. R. Soc. Lond. A 267, 45–61.Google Scholar
AMERICAN INSTITUTE OF PHYSICS 1972 American Institute of Physics Handbook, vol. 5, pp. 123, 133. McGraw-Hill.
Arp, P. A., Foister, R. T. & Mason, S. G., 1980 Some electrohydrodynamic effects in fluid dispersions. Adv. Colloid Interface Sci. 12, 295–356.Google Scholar
ASTM 1987 Annual Book ASTM Standards D 924–82b A-C loss characteristics and relative permittivity (dielectric constant) of electrical insulating liquids. pp. 147–156.
Basaran, O. A. & Scriven, L. E., 1988 The Taylor pump: viscous free surface flow driven by electric shear stress. Chem. Engng Commun. 67, 259–273.Google Scholar
Baygents, J. C. & Saville, D. A., 1989 The circulation produced in a drop by an electric field: A high field strength electrokinetic model. In Drops & Bubbles: Third Intl Colloq. (ed. T. Wang), pp. 7–17, American Institute of Physics.
Davies, J. T. & Rideal, E. K., 1963 Interfacial phenomena, 2nd edn. Academic.
Flumerfelt, R. W.: 1980 Effects of Dynamic Interfacial Properties on Drop Deformation and Orientation in Shear and Extensional Flow Fields. J. Colloid Interface Sci. 76, 330–349.Google Scholar
Garton, C. G. & Krasucki, Z., 1964 Bubbles in insulating liquids: stability in an electric field. Proc. R. Soc. Lond. A 280, 211–226.Google Scholar
Hartshorn, L., Parry, J. V. L. & Essen, L. 1955 The measurement of the dielectric constant of standard liquids. Proc. Phys. Soc. Lond. B 68, 422–446.Google Scholar
Larrendo, L. & St. John Manley, R. 1981 Electrostatic fiber spinning from melts: I. Experimental observations on fiber formation and properties, II. Examination of the flow field in an electrically driven jet, III. Electrostatic deformation of a pendant drop of polymer melt. J. Polymer Sci. Polymer Phys 19, 909–940.Google Scholar
Maryott, A. A. & Smith, E. R., 1951 Table of Dielectric Constants of Pure Liquids. National Bureau of Standards Circular 514, US Government Printing Office.
Melcher, J. R.: 1976 Electric fields and forces in semi-insulating liquids. J. Electrostat. 2, 121.Google Scholar
Melcher, J. R.: 1981 Continuum Electromechanics. MIT Press.
Melcher, J. R. & Taylor, G. I., 1969 Electrohydrodynamics: a review of the role of interfacial shear stresses. Ann. Rev. Fluid Mech. 1, 111–146.Google Scholar
Miller, B., Penn, L. S. & Hedvat, S., 1983 Wetting force measurements on fibers. Colloids Surfaces 6, 49–61.Google Scholar
Moriya, S., Adachi, K. & Kotaka, T., 1985 Effect of electric field on the morphology of a poly(ethylene oxide) polystyrene blend. Polymer Commun. 26, 235–237.Google Scholar
Moriya, S., Adachi, K. & Kotaka, T., 1986 Deformation of droplets suspended in viscous media in an electric field: I. Rate of deformation, II. Burst behaviour. Langmuir 2, 155–165.Google Scholar
Nishiwaki, T., Adachi, K. & Kotaka, T., 1988 Deformation of viscous droplets in an electric field: poly(propylene oxide)/poly(dimethylsiloxane) systems. Langmuir 4, 170–175.Google Scholar
Oguz, H. N. & Sadhal, S. A., 1989 Fluid dynamics and stability analysis of a compound drop in an electric field. Q. J. Mech. Appl. Maths 42, 65–83.Google Scholar
O'Konski, C. T. & Thacher, H. C. 1953 The distortion of aerosol droplets by an electric field. J. Phys. Chem. 57, 955–958.Google Scholar
Scriven, L. E.: 1960 Dynamics of a fluid interface. Chem. Engng Sci. 12, 98–108.Google Scholar
Scott, T. C. & Wham, R. M., 1989 An electrically driven multistage countercurrent solvent extraction device: the emulsion phase contactor. Ind. Engng Chem. 28, 94.Google Scholar
Sherwood, J. D.: 1988 Break-up of fluid droplets in electric and magnetic fields. J. Fluid Mech. 188, 133–146.Google Scholar
Stone, H. A. & Leal, L. G., 1990 The effects of surfactants on drop deformation and breakup. J. Fluid Mech. 220, 161–186.Google Scholar
Taylor, G. I.: 1966 Studies in electrohydrodynamics. I. The circulation produced in a drop by an electric field. Proc. R. Soc. Lond. A 291, 159–166.Google Scholar
Torza, S., Cox, R. G. & Mason, S. G., 1971 Electrohydrodynamic deformation and burst of liquid drops. Phil. Trans. R. Soc. Lond. 269, 259–319.Google Scholar
Venugopal, G., Krause, S. & Wnek, G. E., 1989 Modification of polymer blend morphology using electric fields. J. Polymer Sci. C: Polymer Lett. 27, 497–501.Google Scholar