Dresden 2003 – wissenschaftliches Programm
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DY: Dynamik und Statistische Physik
DY 53: Statistical physics (general) II
DY 53.3: Vortrag
Freitag, 28. März 2003, 12:00–12:15, G\"OR/229
Equilibrium shape of liquid microstructures in electric fields — •Juergen Buehrle1, Marguerite Bienia2, Stephan Herminghaus1, and Frieder Mugele1 — 1Universitaet Ulm, Abt. Angewandte Physik, Albert-Einstein-Allee 11, 89081 Ulm — 2Laboratoire de Spectrometrie, Physique, BP 87, 38402 Saint Martin d’Heres, Cedex, France
We studied surface profiles close to the edge of a partially wetting conductive liquid in presence of electric fields. The grounded liquid rests on a dielectric layer on top of an electrode. If a voltage is applied between liquid and electrode, the electric field diverges at the edge. This induces a distortion of the liquid-gas interface, which we investigated numerically and experimentally. We obtained the equilibrium profile iteratively by calculating the electrostatic potential for a given surface profile and subsequently readjusting the latter by balancing the electrically induced pressure on the surface and the capillary pressure. The asymptotic contact angle far away from the contact line depends on the voltage in agreement with Lippmann’s equation. Closer to the contact line, the profile assumes a curvature, which diverges algebraically as the contact line is approached. The surface profile and the substrate intersect with a finite angle close to Young’s contact angle. An asymptotic model shows that this is in accordance with the infinite electrostatic pressure at the substrate. Theory shows that the electric pressure for a wedge with Young’s angle as opening angle diverges algebraically with an exponent close to the one found numerically. Moreover, we verified experimentally that the curvature of the surface profile increases in quantitative agreement with the simulations.