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DY: Fachverband Dynamik und Statistische Physik

DY 35: Complex Fluids and Soft Matter 2 - organized by Uwe Thiele (Münster) (joint session DY/CPP)

DY 35.4: Invited Talk

Wednesday, March 24, 2021, 10:00–10:30, DYa

When surface viscosities rule: Bubble relaxation and thin film wrinkling — •Kirsten Harth — Institut für Physik, Otto von Guericke Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg

The dynamics of liquid drops and gas bubbles in a surrounding fluid is a classic field of fluid mechanics, studied for over a century. The mathematical problem can be complex already for the case of clean fluid-fluid interfaces, characterized solely by a constant surface tension. However, applications such as ink-jet printing, emulsion characterization or typical biologically inspired systems usually deal with more complex interfacial properties, e.g., adsorbed fluid or contaminant films. Those can completely dominate the overall shape dynamics.

Merged centimeter-sized soap bubbles or rupturing micrometer-thick soap films are a simple yet ideal model system for surface-tension based relaxation. Replacing the soap film by a more complex membrane, nanometer-thin liquid crystalline films in our case, introduces qualitatively new effects due to reorganization of the membrane upon surface area reduction. The talk highlights two aspects: First, the consequences of an effective interfacial viscosity for the relaxation dynamics, known also from interfacial fluid films or adsorbed surfactant layers. Second, out-of-plane bulging and dynamic wrinkling of the interfacial membrane in response to external stress. Experiments will be accompanied by a theoretical / numerical analysis.