The non-local repercussions of partial jamming in dense granular flows
  This paper establishes a link between the non-local behaviour of granular materials and the presence of transient clusters of jammed particles within the flow. These clusters are first evidenced in simulated dense granular flows subjected to plane shear, and are found to originate from a mechanism of multiple orthogonal shear banding. A continuum non-local model, similar in form to the non-local Cooperative model, is then derived by considering the spatial redistribution of vorticity induced by these clusters. The non-locality length scale is thus expressed in terms of the cluster size. The purely kinematic nature of this derivation indicates that non-local behaviour should be expected in all glassy materials, regardless of their local constitutive law, as long as they partially jam during flow. 
Prashidha Kharel and Pierre Rognon
cond-mat.soft