Coexisting static and flowing regions in a centrifuging granular heap

We report an unexpectedly rich variety of new flow patterns on a granular heap that is centrifuged so as to simulate a reduction in gravity. These surface patterns exhibit coexisting static and flowing regions that depend strongly on centrifugal stress, but surprisingly not on mass flow rate. A discrete cellular automata model reproduces some of the patterning features and indicates that subsurface jamming may precipitate the formation of localized frozen patterns on the surface. This model provides insights into the mechanics of granular flows under controlled stress environment and jammed-to-flowing transitions in granular media.