Plastic flow in amorphous solids: from particle-scale to meso-scale.

Amorphous solids flow plastically when driven at sufficiently large stress. Examples include: metallic and polymeric glasses; soft glassy materials such as dense suspensions, pastes, emulsions, and foams; granular materials, etc. During flow, particles rearrange in so-called shear transformation zones (STZs) to accommodate the deformation and relieve the imposed stress. Models can describe the kinematics and dynamics of these rearrangements either explicitly at the particle-scale or, more schematically, at a coarse-grained scale where particle-level details are abstracted away. We will discuss how the results from coarse-grained simulations agree with or differ from particle-based simulations and how this depends on: the way disorder is introduced, the precise way the STZs are coupled to each other elastically, the way finite rate driving is modeled, etc. In particular, we will discuss: the spectrum of dissipative stress relaxation events; the local-strain and particle displacement statistics; emergent spatial structures; and the dependence of these on driving rate or stress.