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DY: Fachverband Dynamik und Statistische Physik

DY 40: Complex Fluids and Soft Matter 3 - organized by Uwe Thiele (Münster) (joint session DY/CPP)

DY 40.1: Talk

Wednesday, March 24, 2021, 11:00–11:20, DYa

Thermally driven material transport in thin freestanding films — •Torsten Trittel, Kirsten Harth, Christoph Klopp, and Ralf Stannarius — Otto-von-Guericke Universität, 39106 Magdeburg, Germany

In addition to their important role in display applications, liquid crystals are attractive in the field of fundamental physics. Smectics can form thin free-standing films with aspect ratios exceeding one million to one (width/thickness). These homogeneously thin films serve as an ideal model system for the study of two-dimensional hydrodynamics. We investigate thermally driven material transport within the film plane under microgravity conditions. Temperature differences in the film lead to thermocapillary (Marangoni) flow. In materials with a normal (negative) temperature coefficient of the surface tension dσ/dT<0, temperature inhomogeneities lead to material transport from the warm to the cold film edge. In materials with dσ/dT>0, flow is reversed. We present a quantitative model, which predicts that the temperature difference between the hot and cold film edge is the relevant parameter, not the gradient as in conventional thermoconvection.