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Phys. Rev. Lett. 62, 1496–1499 (1989)

Fingering instability in thin wetting films

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S. M. Troian, X. L. Wu, and S. A. Safran
Corporate Research Laboratories, Exxon Research and Engineering Co., Clinton Township Rt. 22E, Annandale, New Jersey 08801

Received 1 July 1988; published in the issue dated 27 March 1989

We report on a new hydrodynamic instability which occurs at the spreading edge of a thin wetting film. A drop of aqueous surfactant solution placed on a glass surface moistened with a thin layer of water spreads by propagating fingers, whose velocity and shape depend on the thickness of the ambient water layer and on the surfactant concentration. The two fluids are miscible and show negligible viscosity difference, ruling out a Saffman-Taylor instability. We propose that the Marangoni effect, which is fluid flow induced by gradients in surface tension, drives the instability.

© 1989 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.62.1496
DOI:
10.1103/PhysRevLett.62.1496
PACS:
47.20.Dr, 68.15.+e, 68.45.Gd