Regensburg 2010 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 7: Stochastic processes, brownian motion, and transport
DY 7.2: Talk
Tuesday, March 23, 2010, 10:00–10:15, H46
Colloidal Transport Through Micro porous Media — •Yujie Li1,2, Christian Scholz2, and Clemens Bechinger1,2 — 1Max-Planck-Institut für Metallforschung, Heisenbergstrasse 3, 70569 Stuttgart, Germany — 22. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
The transport properties of colloidal particles were studied on a single particle level in quasi two-dimensional disordered micro porous structures with a temporal resolution of 2 ms and spatial resolution of 0.3 µm. Different hydrodynamic dispersion mechanisms, such as Taylor dispersion, mechanical dispersion, and hold-up of particles in stagnant regions, were visualized in real space. In agreement with theoretical predictions, we find the mean square displacement (MSD) to increase with time t according to a power law ⟨ X2⟩ ∼ tα, where α varies for different regimes. From the crossover between ballistic (α=2) and super diffusive (α>1) transport, the characteristic length ξ of the structures was estimated and compared with the structural correlation length ξ0 defined in the flow direction. By plotting the average velocities as a function of the pressure drop, the permeabilities of different structures were derived and studied in accordance with the pore size.