title: Apparent wall slip in non-Brownian hard-sphere suspensions.
abstract: We analyze apparent wall slip, the reduction of particle concentration near the wall, in hard-sphere suspensions at concentrations well below the jamming limit utilizing a continuum level diffusion model. The approach extends a constitutive equation proposed earlier with two additional potentials describing the effects of gravitation and wall-particle repulsion. We find that although both mechanisms are shear independent by nature, due to the shear-rate-dependent counter-balancing particle migration fluxes, the resulting net effect is non-linearly shear dependent, causing larger slip at small shear rates. In effect, this shows up in the classically measured flow curves as a mild shear thickening regime at the transition from small to intermediate shear rates.
authors.affiliation: Department of Applied Physics, School of Science, Aalto University, P.O. Box 11100, FI-00076, Aalto, Finland.
authors.forename: Marko
authors.initials: M
authors.lastname: Korhonen
authors.forename: Mikael
authors.initials: M
authors.lastname: Mohtaschemi
authors.forename: Antti
authors.initials: A
authors.lastname: Puisto
authors.forename: Xavier
authors.initials: X
authors.lastname: Illa
authors.forename: Mikko J
authors.initials: MJ
authors.lastname: Alava