ABSTRACT
The behavior of flowing powders is very different from that of fluids. Flowing powders do not exhibit fluid viscosity; rather, energy dissipation in flowing powders is due to frictional and collisional interactions between particles. In contrast to the increasing amount of work in the physics literature on the collisional flow of large grains, the focus of the present work is on smaller-sized bulk powders that are industrially more relevant and where a continuum approach may be more advantageous. Further, the focus of this chapter is on the incipient and relatively slow frictional-flow regimes, in which frictional effects are dominant. The details of the chapter include flow in hoppers (Section 9.2), slow-frictional flows (Section 9.3) and characterization of bulk powders (Section 9.4).
