A hierarchy of granular continuum models: Why flowing grains are both simpleand complex
Author(s)
Kamrin, Kenneth N
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ranular materials have a strange propensity to behave as either a complex media or a simple media depending on the precise question being asked. This review paper offers a summary of granular flow rheologies for well-developed or steady-state motion, and seeks to explain this dichotomy through the vast range of complexity intrinsic to these models. A key observation is that to achieve accuracy in predicting flow fields in general geometries, one requires a model that accounts for a number of subtleties, most notably a nonlocal effect to account for cooperativity in the flow as induced by the finite size of grains. On the other hand, forces and tractions that develop on macro-scale, submerged boundaries appear to be minimally affected by grain size and, barring very rapid motions, are well represented by simple rate-independent frictional plasticity models. A major simplification observed in experiments of granular intrusion, which we refer to as the ‘resistive force hypothesis’ of granular Resistive Force Theory, can be shown to arise directly from rate-independent plasticity. Because such plasticity models have so few parameters, and the major rheological parameter is a dimensionless internal friction coefficient, some of these simplifications can be seen as consequences of scaling.
Date issued
2017-06Department
Massachusetts Institute of Technology. Department of Mechanical EngineeringJournal
EPJ Web of Conferences
Publisher
EDP Sciences
Citation
Kamrin, Ken. “A Hierarchy of Granular Continuum Models: Why Flowing Grains Are Both Simple and Complex.” Edited by F. Radjai, S. Nezamabadi, S. Luding, and J.Y. Delenne. EPJ Web of Conferences 140 (2017): 01007 © 2017 The Authors, published by EDP Sciences
Version: Final published version
ISSN
2100-014X