Élisabeth guazzelli (IUSTI, Marseille). Rheology of dense suspensions of non colloidal particles.

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 (e.g. yield-stress fluids) that we will also address.

This work has been done in collaboration with F. Boyer, J. E. Butler, E. Couturier, S. Dagois-Bohy, L. M. Davidson, S. Hormozi, O. Pouliquen, P. R. Nott, S. Shaikh, B. Snook, S. Strednak, F. Tapia.

Related references:

Nott P., Guazzelli E, and Pouliquen O. 2011 The suspension balance model revisited, Phys. Fluids 23, 043304.

Boyer F., Pouliquen O., and Guazzelli E. 2011 Dense suspensions in rotating-rod flows: normal stresses and particle migration, J. Fluid Mech. 686, 5-25 (Focus on Fluid: Hinch E. J. 2011 The measurement of suspension rheology, J. Fluid Mech. 686, 1-4).