Morphological transitions in partially gas-fluidized granular mixtures.

Experiments were conducted to investigate pattern formation during the defluidization of a partially fluidized bimodal granular mixture. Partial fluidization occurs when the system is driven at gas velocities that are insufficient to fluidize all of the constituent particles. Over time, the granular mixture evolves into a variety of patterns depending on the concentrations of large and small particles and the gas velocity.