Levich Institute Seminar Announcement, 02/05/2013
Steinman Hall, Room #312
(Chemical Engineering Conference Room)
Dr. Ryohei Seto
City College of CUNY
"Compressive Consolidation of Particulate Gels"
Compressive consolidation of particulate gels has been studied using a cohesive contact model with the discrete-element method in the quasi-static limit. The 2D simulation of uniaxial compression was applied to fractal networks, and the required compressive stresses Py were evaluated for a wide range of packing fractions ∅ that approached close packing. The compression acts to reduce the length scale of the structures that contribute to the network strength. We observed three stages of compression: (I) elastic deformations of percolation chains are dominant; (II) mesh-like domains, whose strengths are determined by a rolling mode, span from the top to the bottom; and (III) smaller meshes, or lamps, which can be destroyed not only by rolling moments but also by pull-off and sliding forces, span from the top to the bottom. The transitions are characterized by different power laws in the Py - ∅ constitutive relation. We also directly examined how the compression changes the fractal dimension Df and the correlation length ξ. It turns out that both fractal characteristics start to change from the early stage of compression, which is different from the usual assumption in theoretical models.
- Robert Botet (Laboratoire de Physique des Solides, Orsay, France)
- Martine Meireles (Laboratoire de Gnie Chimique, Toulouse, France)
- Gunter K. Auernhammer (Max Planck Institute for Polymer Research, Mainz, Germany)
- Bernard Cabane (ESPCI, Paris, France)
Rheology of particulate suspensions and gels, especially the interplay between hydrodynamic forces and contact forces in sheared suspensions.