SKM 2023 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 32: Focus Session: Physics of Fluctuating Paths (joint session DY/CPP)

DY 32.4: Vortrag

Mittwoch, 29. März 2023, 15:45–16:00, ZEU 160

How Stickiness Can Speed Up Diffusion in Confined SystemsArthur Alexandre1, Matthieu Mangeat2, •Thomas Guérin1, and David Dean11Laboratoire Ondes et matière d'Aquitaine, CNRS/University of Bordeaux, F-33400 Talence, France — 2Center for Biophysics and Department for Theoretical Physics, Saarland University, D-66123 Saarbrücken, Germany

The paradigmatic model for heterogeneous media used in diffusion studies is built from reflecting obstacles and surfaces. It is well known that the crowding effect produced by these reflecting surfaces slows the dispersion of Brownian tracers. In this talk, using a general adsorption desorption model with surface diffusion, we present an analytical theory showing that making surfaces or obstacles attractive can accelerate dispersion. In particular, we show that this enhancement of diffusion can exist even when the surface diffusion constant is smaller than that in the bulk. Even more remarkably, this enhancement effect occurs when the effective diffusion constant, when restricted to surfaces only, is lower than the effective diffusivity with purely reflecting boundaries. We give analytical formulas for this intriguing effect in periodic arrays of spheres as well as undulating microchannels. Our results are confirmed by numerical calculations and Monte Carlo simulations. [Ref: How Stickiness Can Speed Up Diffusion in Confined Systems, Phys Rev Lett 128 210601 (2022)]

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