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DY: Fachverband Dynamik und Statistische Physik

DY 7: Stochastic processes, brownian motion, and transport

DY 7.2: Vortrag

Dienstag, 23. März 2010, 10:00–10:15, H46

Colloidal Transport Through Micro porous Media — •Yujie Li^1,2, Christian Scholz², and Clemens Bechinger^1,2 — 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⟩ ∼ t^α, 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.