  Granulates are ubiquitous in nature and technology, but despite their great
importance, their dynamics are by far less well understood than those of
liquids. We demonstrate in an almost compactly filled flat (Hele-Shaw) cell,
where slow horizontal rotation simulates a variable gravitational force, that
unexpected dynamic structures may arise under geometrical restrictions. The
cell motion drives regular flow in the compact interior, and convection rolls
combine with segregation. The container fill level is crucial for the dynamic
regime. A transition from chute flow at lower fill levels to convection in
densely packed containers is found. These observations suggest the existence of
comparable phenomena in situations where so far no systematic search for
dynamic patterns has been performed.
