Berlin 2018 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 39: Wetting, Microfluidics and Confined Liquids I (joint session CPP/DY)

DY 39.6: Vortrag

Mittwoch, 14. März 2018, 11:15–11:30, C 264

Efficient Condensation and Droplet Removal on Electrowetting-Functionalized Surfaces — Davood Baratian, Ranabir Dey, Harmen Hoek, Dirk van den Ende, and •Frieder Mugele — University of Twente; Physics of Complex Fluids, Enschede, The Netherlands

Efficient condensation of vapor and collection of fog from the atmosphere are important to life in arid environments. Nature has come up with various strategies to optimize the processes by a combination of both topographic and chemical functionalization of solid surfaces that are imprinted passively into the structure of the surface. One crucial aspect in this process is the removal of liquid from the solid surface once it has condensed. In here, we present a novel active approach to improve the efficiency of vapor condensation onto hydrophobic surfaces that are functionalized by electrowetting. We fabricated electrowetting-functionalized surfaces with submerged interdigitated electrodes. Upon exposure to supersaturated vapor droplets condense onto these surfaces in an initially random pattern. As the droplets grow, electrowetting mobilizes the growing drops and induces early coalescence, giving rise to alignment of drops and to early shedding. Mobilization and early shedding are controlled by the effective reduction of contact angle hysteresis in AC electrowetting. Drops are found to grow algebraically, initially with a self-similar growth law as in conventional drop condensation. At a later stage, self-similarity is broken and the statistical drop size distribution is altered. We discuss potential applications in terms of heat transfer.