Regensburg 2022 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 23: Complex Fluids and Soft Matter 1 (joint session DY/CPP)

DY 23.5: Vortrag

Mittwoch, 7. September 2022, 10:30–10:45, H18

Repulsion of topological defects in quasi-2D liquid crystal films — •Kirsten Harth1,2 and Ralf Stannarius31Fachbereich Technik, TH Brandenburg, Brandenburg an der Havel, Deutschland — 2MARS und MRTM, Otto von Guericke Universität Magdeburg, Deutschland — 3Institut für Physik und MARS, Otto von Guericke Universität Magdeburg, Deutschland

The dynamics of topological defects is of interest, e.g., in phase transitions, cosmology or structural organization of colloids and active matter. Liquid crystals are a straightforward system allowing optical characterization of defect motion. As anisotropic fluids, they are characterized by orientational order, introducing long-range elastic forces, in addition to liquid-like fluidity with viscosity coefficients related to, e.g., the local shear flow directions respective to the local orientational field. This causes intriguing effects and must not be neglected.

The comparison of recent exeriments [1,2] in free-standing smectic C films to theoretical and numerical predictions [2,3] leaves a number of questions unanswered. A proper consideration of flow coupling and / or of an anistropy of the elastic constants in a simulation with realistic boundary conditions may solve the issues. We explain why elastic anisotropy is particularly important here. Experimental and numerical data are compared to elucidate the effect of elastic constants and flow on the repeulsion dynamics.

[1] A. Missaoui, et al., PR Research 2 013080 (2020). [2] R. Stannarius, K. Harth, PRL 117 157801 (2016). [3] e.g. X. Tang, J. V. Selinger, Soft Matter 13 5481 (2017) ; Soft Matter, 15 587 (2019)

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