Regensburg 2025 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 21: Granular Matter
DY 21.2: Talk
Wednesday, March 19, 2025, 09:45–10:00, H43
Decoding diffusion: insights into ferrogranulate dynamics under competing interactions — •Oksana Bilous1, Kirill Okrugin1, Pedro A. Sánchez1, Ali Lakkis2, Matthias Biersack2, Reinhard Richter2, and Sofia Kantorovich1 — 1Computational and Soft Matter Physics, University of Vienna, Vienna, Austria — 2Experimental Physics 5, University of Bayreuth, Bayreuth, Germany
Granulates with magnetic and non-magnetic particles exhibit unique diffusion behaviors, challenging conventional models. Using experiments and Langevin dynamics simulations, we studied their dynamics under varying magnetic fields and particle compositions.
In steady states, entropic, dipolar, and field-induced forces create distinct distributions: single particles, cluster-bound particles, and migrating particles transitioning between these states. Sub-diffusion occurs exclusively in magnetic particles within clusters, independent of external fields or concentrations. Glass particles remain non-aggregated.
Velocity distributions in high-shaking experiments validate the use of Langevin dynamics, revealing an effective temperature that links structural separations to thermodynamic scaling laws. These findings deepen our understanding of diffusion and force interactions in complex granular systems.
Keywords: viscoelastic phase separation; magnetized granulate; susceptible dipolar hard spheres; network formation; molecular dynamics simulation