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The Spot Model for random-packing dynamics

Journal Article · · Mechanics of Materials
 [1]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); MIT

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.

Research Organization:
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Sponsoring Organization:
USDOE Office of Science (SC)
DOE Contract Number:
FG02-02ER25530
OSTI ID:
882195
Report Number(s):
DOE/ER/25530-2
Journal Information:
Mechanics of Materials, Journal Name: Mechanics of Materials Journal Issue: 8-10 Vol. 38; ISSN 0167-6636
Publisher:
Elsevier
Country of Publication:
United States
Language:
English

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