Regensburg 2013 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 20: Poster: Colloids and Complex Liquids
CPP 20.32: Poster
Dienstag, 12. März 2013, 18:15–20:15, Poster C
Hydrodynamic dispersion of micron-sized colloids in micro structured porous media — •Frank Wirner1, Christian Scholz1, and Clemens Bechinger1,2 — 12. Physikalisches Institut, Universität Stuttgart, Germany — 2Max-Planck-Institut für Intelligente Systeme, Stuttgart, Germany
Hydrodynamic dispersion of solutes and colloids in porous media occurs under the combined actions of a spatially varying velocity field that is caused by the morphology of the porous matrix and molecular diffusion. This spreading apart of initially adjacent colloids is important to a wide variety of processes such as secondary oil recovery, groundwater pollution or blood perfusion inside the body.
We study the dispersion of diluted suspensions of micron-sized colloids in quasi-2D microporous structures, created using soft lithography, over a wide range of Péclet numbers and porosities. A camera system is used to track individual particles and analyze their trajectories. From the obtained trajectories we calculate the velocity field of the particles and determine the first-passage-time distributions that in turn are related to the dispersion coefficients. The porous structures are artificially designed and therefore the structural parameters like Minkowski functionals and pore size distributions are fully known and can be related to the first-passage-time distributions. We discuss the effects that lead to long-tailed distributions.