Effect of particle size distribution and shear rate on relative viscosity of concentrated suspensions

Suspension rheology is of widespread importance to industry and research. The rheology of spherical silica particle suspensions with different particle volume fractions and particle size distribution under different shear rates has been determined experimentally. Furthermore, the volume fraction at random close packing (φrcp) was introduced as the parameter of the initial relative viscosity model. In addition, suspension relative viscosity model including particle volume fraction, particle size distribution, and shear rate was obtained. The results showed that as the particle volume fraction increased, the shear thinning effect of the suspensions became more apparent. The relative viscosity decreased as the shear rate increased, and the decrease rate increased as the suspension particle volume fraction increased. As the range of particle size distribution increased, the relative viscosity of the suspensions decreased significantly, and the relative viscosity of the suspensions was independent of particle size in a certain range. The prediction of the suspension relative viscosity model proposed in this paper had a high degree of matching with the experimental data, effectively predicting the rheology of concentrated suspensions.