Flow and jamming of sheared granular media

Granular materials, such as athermal suspensions, can either be jammed and rigid, or yield and flow. Recent experiments on granular suspensions in a annular shear cell (vibrated and/or sheared) show a hysteretic freezing and melting transition [1, 2]: a crystallised state is found, which can be melted by sufficient shear. The question is open on what are the mechanisms underlying these phenomena and which are the control parameters. Via Molecular Dynamics simulations, we study the rheology of vibrated and sheared granular materials [3). In particular, we aim to understand the nature of a critical line separating crystallised and melted states and the "jammed" region in the phase diagram, as well as the connections with thermal glass formers and colloidal suspensions.