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The Scientific World Journal
Volume 2014 (2014), Article ID 647694, 5 pages
Research Article

Theoretical Model of Droplet Wettability on a Low-Surface-Energy Solid under the Influence of Gravity

1Priority Organization for Innovation and Excellence, Kumamoto University, 2-39-1, Kurokami, Chuo-ku, Kumamoto-shi, Kumamoto 860-8555, Japan
2Department of Nuclear Engineering, Kyoto University, C3-d2S06, Kyoto Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8540, Japan

Received 12 September 2013; Accepted 24 December 2013; Published 8 January 2014

Academic Editors: S. W. Cha and S. Nardini

Copyright © 2014 Yukihiro Yonemoto and Tomoaki Kunugi. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The wettability of droplets on a low surface energy solid is evaluated experimentally and theoretically. Water-ethanol binary mixture drops of several volumes are used. In the experiment, the droplet radius, height, and contact angle are measured. Analytical equations are derived that incorporate the effect of gravity for the relationships between the droplet radius and height, radius and contact angle, and radius and liquid surface energy. All the analytical equations display good agreement with the experimental data. It is found that the fundamental wetting behavior of the droplet on the low surface energy solid can be predicted by our model which gives geometrical information of the droplet such as the contact angle, droplet radius, and height from physical values of liquid and solid.