Regensburg 2022 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 38: Complex Fluids and Soft Matter 2 (joint session DY/CPP)
DY 38.2: Vortrag
Donnerstag, 8. September 2022, 10:15–10:30, H18
Reciprocal and nonreciprocal eigenmodes of viscoelastic fluids — •Juliana Caspers1, Clemens Bechinger2, Nikolas Ditz2, Matthias Fuchs2, Felix Ginot2, Karthika Krishna Kumar2, Luis Frieder Reinalter2, and Matthias Krüger1 — 1Institute for Theoretical Physics, Georg-August Universität Göttingen, 37073 Göttingen, Germany — 2Fachbereich Physik, Universität Konstanz, 78457 Konstanz, Germany
Complex fluids such as wormlike micellar solutions are in general non-Markovian. In equilibrium, their behavior is often well approximated by a simple Maxwell model with one characteristic timescale [1]. Recoil experiments, after a colloidal probe has been sheared through the solvent, however, displayed a double-exponential relaxation [2]. We found excellent agreement of our measurements with a linear two-bath particle model. Depending on whether the optical trap which confines the probe is turned on or off, we find two sets of eigenmodes in our model, corresponding to either nonreciprocal (trap on) or reciprocal (trap off) forces. Using different recoil protocols as well as equilibrium mean square displacement measurements we confirmed the existence of these two different sets of timescales with experiments. Finally, for linear systems, we find a Volterra relation between two memory kernels, characterizing reciprocal and nonreciprocal forcing.
[1] F. Ginot, J. Caspers, M. Krüger, C. Bechinger. Phys. Rev. Lett. 128, 028001 (2022)
[2] F. Ginot, J. Caspers, L. F. Reinalter, K. Krishna Kumar, M. Krüger, C. Bechinger. arXiv:2204.02369 (2022)