Berkeley Fluids Seminar

December 4, 2013

Prof. Peichun Amy Tsai (University of Twente, The Netherlands)

Controlling Splashing and Slippage on Superhydrophobic Surfaces

In this talk, I will demonstrate how to modify surfaces to alter bulk flow using hydrophobic micro-structures. The wax-like micro-textures display superhydrophobicity, yielding a large static contact angle of water droplet with a low contact angle hysteresis. Two dynamical scenarios: drop impact and laminar flow on superhydrophobic surface, will be presented. At a high impact velocity splashing of water droplet can occur, emitting secondary droplets. Moreover, the splashing dynamics is strongly influenced by the micro-patterns of the substrate. In microfluidic laminar flow, the geometry of the liquid-gas interface affects slippage, i.e. drag reduction, using hydrophobic micro-structures. We found that air and air flow play an important role in these two scenarios, revealing the importance of developing an active control of the gas-liquid interface at the flow boundary.

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Acknowledgments

Prof. Graham Fleming (Vice Chancellor for Research, UC Berkeley)

Prof. Eliot Quataert on behalf of The Theoretical Astrophysics Center and the Astronomy Department (UC Berkeley)

Prof. Philip S. Marcus on behalf of the Mechanical Engineering Department (UC Berkeley)

Prof. Michael Manga (Earth and Planetary Science, UC Berkeley)

Prof. Evan Variano (Civil and Environmental Engineering, UC Berkeley)