Dresden 2026 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 54: Statistical Physics: General II
DY 54.3: Talk
Thursday, March 12, 2026, 15:30–15:45, ZEU/0114
Geometry-induced timescales in viscoelastic fluids — •Rupayan Saha1, Niloyendu Roy2, Debankur Das1, Clemens Bechinger2, and Matthias Krüger1 — 1Institute for Theoretical Physics, Georg-August-Universität Göttingen, Göttingen 37073, Germany — 2Fachbereich Physik, Universität Konstanz, Konstanz 78457, Germany
Recoil experiments provide a powerful window into the non-Markovian properties of complex fluids, revealing memory effects that are usually obscured in conventional rheological measurements. While translational recoil of colloidal probes in viscoelastic media has been successfully modelled with few distinct timescales, orientational recoil exhibits an unbounded relaxation spectrum, manifested in the divergence of the recoil amplitude with increasing shear-time (tsh) or system size (L). To resolve its physical origin, we design a first-principles theoretical framework rooted in the geometric constraints of torsional flow. Our model, based on concentric spherical shells, demonstrates that the orthogonality between angular momentum propagation and torsional stress storage generates a radial scaling law for relaxation modes. The theory thus establishes geometry—not material-complexity—as the primary candidate for engineering complex memory in soft matter. We finally elucidate why such long relaxation times have not been previously discovered through conventional rheology.
Keywords: Non-equilibrium Statistical Physics; Transient Dynamics; Non-Markovian Bath; Fluctuation and Response; Microrheology