Abstract
Although substantial progress has been made in recent years in research onsheared granular matter, relatively few studies concentrate on the behavior of materials withvery strong polydispersity. In this paper, shear deformation of a two-dimensional granularmaterial composed of frictional disk-shaped grains with power-law size distribution isanalyzed numerically with a finite-difference model. The analysis of the results concentrateson those aspects of the behavior of the modeled system that are related to its polydispersity. Itis demonstrated that many important global material properties are dependent on the behaviorof the largest grains from the tail of the size distribution. In particular, they are responsiblefor global correlation of velocity anomalies emerging at the jamming transition. They alsobuild a skeleton of the global contact and force networks in shear-jammed systems, leadingto the very open, “sparse” structure of those networks, consisting of only ~ 35% of all grains.The details of the model are formulated so that it represents fragmented sea ice moving ona two-dimensional sea surface; however, the results are relevant for other types of stronglypolydisperse granular materials, as well.
Highlights
Granular materials are an example of systems in which relatively simple interactions between similar discrete objects produce very complex emergent behavior
The results of the present study suggest that many global characteristics of granular materials with very wide grain-size distributions (GSD), including those indicative of the jamming phase transition, are determined by the behavior of and interactions between a relatively small subset of the largest grains from the tail of the GSD
The percolation of the contact networks in the analyzed system with PL GSD is associated with the following changes of the global system properties: (i) rapid increase of the entropy of grain velocity anomalies; (ii) emergence of large-scale correlation between the velocity anomalies of the largest grains; (iii) rapid increase of the mean contact number and the fraction of non-rattler grains, accompanied by a rapid decrease of the contact network anisotropy; and (iv) rapid increase of the contact lifetimes, especially between the largest grains
Summary
Granular materials are an example of systems in which relatively simple interactions between similar discrete objects (grains, or particles) produce very complex emergent behavior. The behavior of very strongly polydisperse materials in those settings remains very poorly understood Most works, including those cited above, concentrate on materials with narrow grain-size distributions (GSD). This work is a continuation of previous numerical studies on sea ice composed of disk-shaped floes with power-law size distribution [19,20,21]. It examines the behavior of a 2D polydisperse granular material composed of frictional grains under pure-shear deformation (constant packing fraction, or, in the sea-ice nomenclature, ice concentration A).
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