Regensburg 2007 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 17: Micro and Nano Fluidics I: Structured Substrates

CPP 17.1: Invited Talk

Wednesday, March 28, 2007, 14:00–14:30, H37

Liquid distribution in a granular pile — Mario Scheel, Martin Brinkmann, •Stephan Herminghaus, and Ralf Seemann — MPI for Dynamics and Self-Organization

The addition of small amounts of liquid to a granulate dramatically chsnges the mechanical properties of the latter. This is due to capillary bridges forming between mutually adjacent grains in the pile, which exert an attractive force by virtue of the surface tension of the liquid. However, within a wide range of liquid content the mechanical properties of a wet granulate are surprisingly independent. This peculiar behavior is explored experimentally and theoretically by means of the liquid distribution within the granulate. The liquid distribution within a model granulate consisting of glass beads is analyzed experimentally by x-ray tomography as function of wettability and packing density. Liquid morphologies and the resulting capillary forces are calculated numerically by a minimization of the surface energy of the liquid. The constant mechanical properties of wet granulates for a large range of liquid contents is a result of one particular type of liquid morphology, which dominates over all other possible morphologies in case of a wetting liquid.