The viscous deposition of a liquid film on the inside of a capillary has been experimentally investigated with a focus on the relationship between the film thickness and surface wettability. With distilled water as a working fluid tests were run in a 622 microns diameter glass tube with contact angles of 30° and 105°, respectively. In the first set of experiments the tube was uncoated while in the second set a fluoropolymer coating was applied to increase the contact angle. A film thickness dependence with the contact angle θ (surface wettability) as well as the Capillary number in the form hR ∼ Ca2/3/cosθ is inferred from scaling arguments. For partial wetting it may explain the existence of a thicker film for nonzero contact angle. It was further found that the non-wetting case of 105° contact angle deviates significantly from the existing theories, the film thickness presenting a weak dependence with the Capillary number. This deviation as well as the apparent non-uniqueness of the solution is thought to be caused by the film instability (rupture) observed during the tests. The thickness of the deposited film as a function of the Capillary number was estimated from the liquid mass exiting the capillary and the gas-liquid interface (meniscus) velocity, and compared to Bretherton’s data and a correlation proposed by Quere. The film thickness measurements as well as the meniscus velocity were determined with the aid of a Photron high speed camera with 10000 frames per second sampling capability coupled with a Nikon TE-2000 inverted microscope and a Precisa electronic balance.
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ASME 2009 7th International Conference on Nanochannels, Microchannels, and Minichannels
June 22–24, 2009
Pohang, South Korea
Conference Sponsors:
- Nanotechnology Institute
ISBN:
978-0-7918-4349-9
PROCEEDINGS PAPER
The Effect of Surface Wettability on Viscous Film Deposition
Alexandru Herescu,
Alexandru Herescu
Michigan Technological University, Houghton, MI
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Jeffrey S. Allen
Jeffrey S. Allen
Michigan Technological University, Houghton, MI
Search for other works by this author on:
Alexandru Herescu
Michigan Technological University, Houghton, MI
Jeffrey S. Allen
Michigan Technological University, Houghton, MI
Paper No:
ICNMM2009-82263, pp. 661-664; 4 pages
Published Online:
September 21, 2010
Citation
Herescu, A, & Allen, JS. "The Effect of Surface Wettability on Viscous Film Deposition." Proceedings of the ASME 2009 7th International Conference on Nanochannels, Microchannels, and Minichannels. ASME 2009 7th International Conference on Nanochannels, Microchannels and Minichannels. Pohang, South Korea. June 22–24, 2009. pp. 661-664. ASME. https://doi.org/10.1115/ICNMM2009-82263
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