Complexity, segregation, and pattern formation in rotating-drum flows

Abstract

Rotating-drum flows span a variety of research areas, ranging from physics of granular matter through hydrodynamics of suspensions to pure liquid coating flows. Recent years have seen an intensified scientific activity associated with this unique geometrical configuration, which has contributed to our understanding of related subjects such as avalanches in granules and segregation in suspensions. The existing literature related to rotating-drum flows is reviewed, highlighting similarities and differences between the various flow realizations. Scaling laws expressing the importance of different mechanisms underlying the observed phenomena have been focused on. An emphasis is placed on pattern formation phenomena. Rotating-drum flows exhibit stationary patterns as well as traveling and oscillating patterns; they exhibit reversible transitions as well as hysteresis. Apart from the predominant cylindrical configuration, this review covers recent work done with tumblers having other geometries, such as the sphere and the Hele-Shaw cell

Resolving a paradox of anomalous scalings in the diffusion of granular materials

“…Particles below it (the fixed bed) are in static equilibrium and perform solid body rotation in unison with the container (41)(42)(43). This flow rapidly reaches steady state (10,42), at which point, to a good approximation, the volume fractions and macroscopic (averaged) densities of the material in the flowing layer and the bulk are constant and equal. For a monodisperse granular material, all particles are identical, and c is the concentration of the tagged particles (e.g., black in color), while 1 − c is the concentration of the nontagged particles (e.g., white in color).…”

“…In particular, granular flow in a long rotating horizontal drum has proven to be a simple but important system to understand (10). Recently, it has been suggested that axial diffusion in this system is anomalous (11).…”

Granular dynamics of cohesive powders in a rotating drum as revealed by speckle visibility spectroscopy and synchronous measurement of forces due to avalanching

“…Granular materials and powders in rotating drums are of wide interest not only because of their extensive use in the chemical, minerals, pharmacutical and food processing contexts, but also as model systems in the study of natural disasters, such as avalanches or landslides (Meier et al, 2007;Seiden and Thomas, 2011).…”

Segregation and convection rolls in two-dimensional packings

“…That is what makes granular science very exciting. If a bidisperse mixture of differently sized grains is rotated horizontally in a cylindrical drum, a complex scenario of segregation processes is found [2]. Radial segregation takes place in the first ≈5 rotations, followed by axial segregation after ≈100 rotations.…”