Rheology of dense suspensions of non colloidal particles

Abstract

Abstract. Dense suspensions are materials with broad applications both in industrial processes (e.g. waste disposal, concrete, drilling muds, metalworking chip transport, and food processing) and in natural phenomena (e.g. flows of slurries, debris, and lava). Despite its long research history and its practical relevance, the mechanics of dense suspensions remain poorly understood. The major difficulty is that the grains interact both by hydrodynamic interactions through the liquid and by mechanical contact. These systems thus belong to an intermediate regime between pure suspensions and granular flows. We show that we can unify suspension and granular rheology under a common framework by transferring the frictional approach of dry granular media to wet suspensions of spherical particles. We also discuss non-Newtonian behavior such as normal-stress differences and shear-induced migration. Beyond the classical problem of dense suspension of hard spheres which is far from being completely resolved, there are also entirely novel avenues of study concerning more complex mixtures of particles and fluids such as those involving other types of particles (e.g. fibers) or non-Newtonian fluids that we will also address.

On the mixing enhancement in concentrated non-colloidal neutrally buoyant suspensions of rigid particles using helical coiled and chaotic twisted pipes: A numerical investigation

“…In fact, this could be explained by the fact that the suspension flow goes from diluted to concentrated regime where the particles dynamics and their interaction with the flow field becomes different. These two different regimes were manifested through previous rheological measurements of the suspension such as the particles normal stress differences (see [8,25]).…”

“…Numerically speaking, scientists have been trying to quantify the complex rheology of laminar and Stokes flows of concentrated suspensions of rigid particles [24,25]. The flows of concentrated neutrally buoyant isothermal suspensions are known to exhibit a phenomenon of SIM in addition to a non-Newtonian behavior characterized by the presence of a first, and a second NSD N 1 and N 2 , respectively [8].…”