Although flowing granular materials have been formally studied for over two hundred years, their behavior is still poorly understood relative to fluids, solids, and gases. Sheared granular materials with differing particle properties (e.g., size, density, shape) segregate (de-mix) due to percolation (small particles fall between large ones) and buoyancy (light...
Nonlinear systems with many interacting components often exhibit behaviors that cannot be anticipated, even in principle, by only knowing the properties of the constituent parts and thereby emerge as a result of interactions between the parts. Examples of such systems range from power grids and financial markets to food networks...