Structures formation in
shear flow of mixtures of rough particles and Newtonian fluids
S. Vahid
and M.A. Koenders
The interaction in a fluid of two rough particles is analysed in the lubrication limit. Because particles have asperities they may collide and exert a rebound force on one another. The insight obtained from the analysis is deployed in a numerical simulation of many particles in a fluid. This is done by shearing two rough walls in a discrete element method. The resulting flow patterns are reported and analysed. One feature that comes to the fore is the formation of ephemeral structures, consisting of alignments of particles in the direction of the compressive quadrant of the shear.
These structures are quantified by means of a spatial-temporal spectral analysis of the particle concentrations. These are reported for various microscopic and macroscopic parameters: surface asperity size, channel width and particle concentration. The work will contribute to the phrasing of overall constitutive laws for this type of slurry.