Berlin 2012 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 21: Poster: Wetting, Micro and nanofluidics
CPP 21.13: Poster
Mittwoch, 28. März 2012, 11:00–13:00, Poster A
Measuring Flow Properties in Porous Media With Micron-sized Colloidal Tracers — •Christian Scholz1, Frank Wirner1,2, and Clemens Bechinger1,2 — 12.Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany — 2Max-Planck-Institut für Intelligente Systeme, Heisenbergstraße 3, 70569 Stuttgart, Germany
The understanding of transport and flow phenomena in porous media is important for many problems which arise in various fields of science and engineering, ranging from agricultural, biomedical, chemical and petroleum engineering to soil sciences. Although the literature on porous media has been growing rapidly over the last decades it is still unclear, how transport properties of liquids through porous materials can be related to their structure. We use finite-sized colloidal tracers to study flow and transport properties in random quasi-2D microfluidic porous media and study the effects of the tracer size on the mean and local tracer velocity within such structures. Significant differences in the mean velocities of different-sized tracers are found even for very low Stokes numbers, due to differing particle height distributions. We discuss the implications of these deviations for permeability measurements from particle tracking velocimetry. By applying an exponentially decreasing pressure drop we overcome the size dependence and measure the permeability of porous structures independently of tracer-size effects in the structure.