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The influence of surface forces on thin film drainage between a fluid drop and a flat solid

journal contribution
posted on 06.12.2017, 00:00 by Jason Connor, R Horn
An experiment is described in which a mica surface is driven towards a mercury drop immersed in aqueous electrolyte. Under appropriate conditions, hydrodynamic pressure in the aqueous film creates a classical dimple in the mercury drop. The use of optical interferometry and video recording to monitor the shape of the drop and the thickness of the aqueous film with sub-nanometre resolution yields a high density of precise data showing the formation and evolution of the dimple as the film drains. Variation of electrical potential applied to the mercury phase allows control of the surface forces acting between the drop and the mica surface, so that the effect of surface forces on the film drainage process is highlighted. It is found that the film thickness at the centre of the dimple and the lateral extent of the dimple are not significantly affected by surface forces. On the other hand, the minimum film thickness at the edge of the dimple is sensitive even to weak surface forces. Since this minimum film thickness is a major determinant of the film drainage rate, it is shown that surface forces have an important effect on the overall drainage process.

Funding

Category 1 - Australian Competitive Grants (this includes ARC, NHMRC)

History

Volume

123

Start Page

193

End Page

206

Number of Pages

14

ISSN

1359-6640

Location

United Kingdom

Publisher

RSC Publishing

Language

en-aus

Peer Reviewed

Yes

Open Access

No

External Author Affiliations

University of South Australia;

Era Eligible

Yes

Journal

Faraday discussions.

Exports

CQUniversity

Exports