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DY: Dynamik und Statistische Physik

DY 34: Poster

DY 34.92: Poster

Montag, 7. März 2005, 15:30–18:00, Poster TU D

Distribution of Liquid in Wet Granular Matter — •Mario Scheel¹, Klaus Mecke², Stephan Herminghaus¹, Marco DiMichiel³, and Ralf Seemann¹ — ¹MPI for Dynamics and Self-Organization, D-37073 Göttingen — ²University of Erlangen, D-91058 Erlangen — ³ESRF, F-38043 Grenoble Cedex 9,

When wetted with moderate amounts of liquid, granular materials change their mechanical properties dramatically. This is most prominently observed comparing dry sand, as found in the desert, to the shapeable solid of which sand castles are made. The reason for this effect are the microscopic capillary bridges forming between adjacent grains, which by virtue of surface tension make a soft solid out of what was a heavy dissipative gas. The morphology of this complex network of liquid bridges is directly connected to the mechanical properties of the wet granulate. We have studied this network by using X-ray tomography, which we applied to random packings of small (few 100 microns diameter) glass spheres, wetted by a contrasting liquid. Upon increasing the liquid content, we find a crossover from individual bridges to random clusters of liquid. Geometrical quantities are compared to what has been obtained earlier with optical immersion techniques. A particular advantage of our setup is the possibility to study dynamical phenomena, which allowed us to investigate the imbibition of a front of liquid into the granular pile.