Inertial shear thickening in non-Brownian suspensions

In shear thickening suspensions, viscosity appears to increase when the shear rate increases. In non-Brownian suspensions, different modes of shear thickening behavior have been identified. These modes are attributed to different physical mechanisms such as hydrodynamic interactions among particles, transition from frictionless to frictional rheology, transition from a viscous to an inertial regime, microstructural effects, etc. We have designed a model non-Brownian suspension to study experimentally the viscous to inertial mode of shear thickening behavior. We discuss the inertial shear thickening mode in detail and show that transition from the viscous to the inertial regime may occur at particle Reynolds number smaller than 1 in the limit of jamming volume fraction. In addition, we provide a closure for shear stresses in inertial suspensions.