Granular Materials near Jamming

This talk focuses on materials near the jamming transition. A key aspect of jamming is the system density. If the density is low, then the granular material will flow; if it is high, then the system will be mechanically stable, and hence unable to flow. This suggests a transitional density, below which flow will always occur, and above which no flow will occur, until the system is sheared strongly enough. For frictional grains, reality is more complex and more interesting. There exists a range of densities for which either flowing or jammed states are possible, depending on the shear stress. For instance, if a system is prepared in this 'shear jamming' density range in a stress-free state, the application of shear strain leads to a jammed (shear jammed) state. This talk will explore the shear jamming process, the dynamics that can occur near shear jamming, and how this kind of state is manifested in flows of particle interest.