Finding Minimal Energy Paths for Droplets on Superhydrophobic Surfaces: A Phase Field Approach

Interest in superhydrophobic surfaces has recently increased due to a number of interesting advances in science and engineering. Here we use a diffuse interface model for droplets on topographically and chemically patterned surfaces in the regime where gravity is negligible. We then examine the transition of droplets between different metastable/stable states by finding the minimal energy paths (MEPs) which correspond to the most probable transition pathways in the configuration space.

In the case of a hydrophobic surface with posts of variable height and separation, we determine the MEPs corresponding to the transition between the Cassie-Baxter and Wenzel states. Additionally, we realize critical droplet morphologies along the MEP, associated saddle points of the free-energy potential and corresponding energy barriers. We analyze and compare the MEPs and free-energy barriers for a variety of surface geometries, droplets sizes, and static contact angles ranging from partial wetting to complete wetting.

Speaker Bio: Kellen obtained his undergraduate degrees in Mathematics and Physics from the University of Utah and Master's degree in Mathematics from the Courant Institute (NYU). He is currently a doctoral student at the Courant Institute expecting to graduate in the Spring of 2013. He is interested in wetting and spreading, physical applications of diffuse interface theory, and complex fluids.

Presentation Slides: PDF

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