Granular flows in split bottom geometries

There is a simple and general experimental protocol to generate slow granular flows that exhibit wide shear zones, qualitatively different from the narrow shear bands usually observed. The essence is to drive the granular medium not from the sidewalls, but to split the bottom of the container that supports the grains in two parts that slide past each other. Here we discuss main features of granular flows in so-called split bottom geometries. We focuss on reviewing the results for dry, slow granular flow. New developments, on faster flows, on flows of particles submerged in fluids, and on flows accompanied by weak vibration will be briefly outlined-these new developments will be discussed in more details in the accompanying talk at P&G 2009