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DY: Fachverband Dynamik und Statistische Physik

DY 24: Complex Fluids and Soft Matter (joint session DY/CPP)

DY 24.5: Vortrag

Dienstag, 17. März 2020, 10:30–10:45, ZEU 160

Thermally driven material transport in thin freestanding films — •Torsten Trittel, Christoph Klopp, Kirsten Harth, and Ralf Stannarius — Otto von Guericke University, Institute for Physics, 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.

[1] Trittel et al., Marangoni Flow in Freely Suspended Liquid Films, Phys. Rev. Lett., 122 (2019)