Flow regimes in fine cohesive powders

Granular materials exhibit several regimes of behavior: plastic, inertial, fluidized, and entrained flow, hut not all materials can pass through all o f these states. Our concern is with the criteria that determine the transit ion from one regime to another and with the boundaries to the various flow regimes that these criteria define. Experimentally we have focused on fine, cohesive powders, where the interparticle cohesive force dominates over gr avitational force and where entrained air can cause moving powder to become fluidized. [S0031-9007(98)08339-2].