CiteULike: dchen's library [662 articles] http://www.citeulike.org/user/dchen/article/2582922 CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dchen/article/2582922 <i>Mechanics of Materials, Vol. 38, No. 8-10. ( 2006), pp. 717-731.</i><br /><br />The diffusion and flow of amorphous materials, such as glasses and granular materials, has resisted a simple microscopic description, analogous to defect theories for crystals. Early models were based on either gas-like inelastic collisions or crystal-like vacancy diffusion, but here we propose a cooperative mechanism for dense random-packing dynamics, based on diffusing "spots" of interstitial free volume. Simulations with the Spot Model can efficiently generate realistic flowing packings, and yet the model is simple enough for mathematical analysis. Starting from a non-local stochastic differential equation, we derive continuum equations for tracer diffusion, given the dynamics of free volume (spots). Throughout the paper, we apply the model to granular drainage in a silo, and we also briefly discuss glassy relaxation. We conclude by discussing the prospects of spot-based multiscale modeling and simulation of amorphous materials. The Spot Model for random-packing dynamics Martin Bazant doi:10.1016/j.mechmat.2005.06.016 Mechanics of Materials, Vol. 38, No. 8-10. ( 2006), pp. 717-731. 2008-03-24T22:29:29-00:00 Mechanics of Materials 38 8-10 717 731 grain model qualifier