I. Rheology of Weakly Flocculated Suspensions of Rigid Particles

P. Snabre , P. Mills

A rheological law for hard spheres in purely hydrodynamic interaction is used to describe the steady state viscosity of weakly aggregated suspensions of rigid particles. The shear viscosity only involves the volume fraction and the maximum packing concentration of particles. Particle aggregation influences the parameters of the reference viscosity law. Within the framework of fractal aggregation, we introduce the volume fraction of aggregates and we derive the equilibrium mean radius of clusters from an effective medium approximation. The proposed rheological equation is close to the phenomenological Casson equation for soft clusters of fractal dimensionality D=2. In a second part, we present rheo-optical experiments for studying the break-up of red cell aggregates in a shear flow and for determining the critical disaggregation shear stress of the flowing suspension mainly representative of the surface adhesive energy between particles. The proposed microrheological model well describes viscometric data in the low shear regime and allows information about the shear induced restructuration and the lifetime of clusters.

Domaines: Articles anciens

P. Snabre, P. Mills. I. Rheology of Weakly Flocculated Suspensions of Rigid Particles. Journal de Physique III, 1996, 6 (12), pp.1811-1834. ⟨10.1051/jp3:1996215⟩. ⟨jpa-00249559⟩