The Powder Flow Working Group was charged by IFPRI to produce a review of research challenges on the flow of powders. It includes academics (Robert Behringer, Michel Louge, James McElwaine, Robert Pfeffer, Sankaran Sundaresan, and Jeorg Schwedes), industrial advisors (Karl Jacob, Thomas Halsey, James Michaels, and Paul Mort), and IFPRI officials (Nikolaas de Jaeger, Roger Place). The group held a meeting on October 21 and 22, 2004 in Newark, NJ to kick-off the activity. Triantafillos (Lakis) Mountziaris represented the NSF.
The group produced two principal deliverables. First, it wrote a series of short articles that are collected in this report. Second, for the NSF's benefit, it outlined broad research directions that the agency should consider to advance knowledge on powder flow that is relevant to industrial problems.
This report is organized from the small scale to the flow scale. Its articles summarize a state of understanding and recommend further work. We begin with considerations of interparticle forces; we then discuss the role of compressibility and cohesion in setting bulk properties; we focus on stresses; we explore similarity and scaling; we sketch numerical techniques; and we delineate regimes of granular flows. We close by discussing chute flows and by considering effects of the interstitial fluid.