Fundamental aspects of solids‐gas flow: Part VI: Multiparticle behavior in turbulent fluids

At Reynolds numbers approaching unity the particles in a solids‐gas system acquire a turbulent motion in response to the turbulence of the ambient fluid. This regime is of particular importance and a discussion of recent theoretical and experimental attempts to describe it is presented. The reaction of the fluid phase to the presence of the particles is equally important. The extent to which the mean and turbulent properties of the fluid motion are affected by the presence of the solids phase is governed by the particle concentration and the fluid and solids Reynolds numbers. The experimental evidence is as yet inconclusive owing to the difficulty of obtaining reliable data. The theoretical attack is similarly made difficult by the need to employ mixed Eulerian and Lagrangian coordinates. A discussion of electrostatic charging phenomena has also been included and it shows that in some systems it exerts an over‐riding influence on the particle motion and momentum transfer.