Regensburg 2007 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 24: Poster I

DY 24.51: Poster

Wednesday, March 28, 2007, 16:00–18:00, Poster D

Shear fluidisation of wet granulates — •Seyed Habibollah Ebrahimnazhad Rahbari, Martin Brinkmann, and Stephan Herminghaus — Dynamics of Complex Fluids, Max- Planck Institute for Dynamics and Self- Organization, Bunsenstr. 10, 37073 Göttingen, Germany

The fluidization of dense wet granular matter in the presence of externally applied shear forces is examined by molecular dynamics-type simulations in two and three dimensions. The granulate is modeled as an assembly of frictionless soft discs, respectively, spheres with a bidisperse size distribution. A short ranged constant attractive force accounts for liquid bridges between adjacent spheres, including the hysteretic nature of capillary interaction [1]. As reported in earlier works on similar models of wet granulates by Schultz [2] and Goll [3], a critical transition between a quiescent and a fluidized state is observed as the amplitude of the shear forces is increased. Since it has been suggested that Lennard-Jones potentials may be too soft to account for the jamming effects at high density [3], we alternatively examined interactions via Hertzian forces. Different dynamic regimes are identified and characterized by the magnitude of drift motion, particle diffusion and the spatial distribution of stresses. In our simulations, shear forces are generated either through a spatially varying force field or by sliding side walls being decorated with a immobilized monolayer of particles.

[1] S Herminghaus, Adv. Phys. 54: 221, (2005)

[2] M Schulz et al., Phys. Rev. E 67: 052301 (2003)

[3 ] C M Goll and K Mecke, private communication