Berlin 2005 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 1: SYMPOSIUM: Dynamics of multi-component fluids I

CPP 1.3: Talk

Friday, March 4, 2005, 10:45–11:00, TU C243

Non Brownian suspensions: pattern formation and rheology — •Anke Lindner, Christophe Chevalier, and Eric Clement — PMMH, Ecole Supérieure de Physique et de Chimie Industrielles, 10, rue Vauquelin, 75231 Paris Cedex 05, France

We study the injection of a simple fluid into a non Brownian suspension. To do so we use a specific model system: a so called iso-dense suspension, where particles and solvent have the same density. For these mixtures gravity does not play a role and thus no sedimentation occurs allowing to adjust the volume fraction of particles over a wide range. When studying pattern formation in a linear Hele-Saw cell filled with the above mentioned suspension two limiting cases are found: for low volume fractions one observes the classical Saffman -Taylor instability. For high volume fractions the granular system is jammed corresponding to a porous media invaded by a viscous fluid. In-between one observes a crossover from a complex fluid like behaviour to a weak porous media with flow induced rearrangements of the pores. The observed patterns, caused by the injection of the simple fluid, are discussed as a function of the rheological properties of the suspension