ABSTRACT
Flows composed of “massive” solid particles are ubiquitous in numerous natural settings (landslides, avalanches, ice ˜oes, planetary rings, etc.) and industries (energy, pharmaceuticals, chemicals, foodstuffs, mining, etc.). For the purposes of this work, “massive” refers to particles in which the Stokes number (St) is relatively high, where the Stokes number is de”ned as the ratio of particle inertia to ˜uid viscosity effects. Namely, St = ρpdpVrel/μ, where ρp and dp are the material density and diameter of the solid particle, Vrel is the relative approach velocity between two particles, and μ is the viscosity of the surrounding ˜uid. For large St, particle-particle collisions dominate the interactions, whereas lubrication forces dominate at small St. Note that the large St ˜ows considered here include both granular systems, in which the role of the interstitial ˜uid is essentially negligible, and gas-solid systems, in which the drag force between the two phases plays a role in addition to particle-particle contacts. Systems with lower St which are not considered here include aerosols, colloidal systems, and liquid-solid suspensions.
