Berlin 2015 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 12: Granular Matter / Contact Dynamics Part II

DY 12.1: Talk

Monday, March 16, 2015, 15:30–15:45, BH-N 128

Dissipation in quasistatically sheared wet and dry sand under confinement — •Maryam Pakpour¹, Jorge E. Fiscina^1,2, Abdoulaye Fall³, Nicolas Vandewalle¹, Christian Wagner², and Daniel Bonn^4,5 — ¹GRASP, Physics Department B5, University of Lièege, B-4000 Lièege, Belgium — ²Experimental Physics, Saarland University, Saarbrücken Germany — ³Laboratoire Navier (UMR CNRS 8205), Universitè Paris Est, Champs-sur-Marne, France — ⁴Van der waals-Zeeman Istitute, University of Amsterdam, Amsterdam, the Netherlands — ⁵Laboratoire de Physique Statistique de l’ENS, 75231 Paris Cedex 05, France

We investigated the stress-strain behavior of granular materials with and without small amounts of liquid near the jamming transition under steady and oscillatory shear. Partially saturated sand has a much higher yield stress and should therefore have a much higher apparent viscosity for slow flows. For this reason, it is commonly believed that dry sand should deform more easily and wet sand shows a larger resistance to flow, i.e., more viscous than dry sand. In this study, using a new technique to quasistatically push the sand through a tube with an enforced parabolic (Poiseuille-like) profile, we minimize the effect of avalanches and shear localization. We observe that the resistance against deformation of the wet (partially saturated) sand is much smaller than that of the dry sand, and that the latter dissipates more energy under flow. This is also observed in large-amplitude oscillatory shear measurements using a rotational rheometer, showing that the effect is robust and holds for different types of flow.