Anomalous diffusion of wall-bounded non-colloidal suspensions in a steady shear flow

We investigate the shear-induced diffusion of concentrated non-colloidal suspensions in a Couette flow. The channel is divided into four zones based on the suspension microstructure and variances of the wall-normal and spanwise displacements for the particles in each zone. Due to the strong spatial coherency induced by the density fluctuations, the suspended particles exhibit anomalous diffusion. The diffusion in the wall-normal direction changes from superdiffusion for the particles next to the wall to subdiffusion for the particles near the core of the channel. It seems that the intermittent jumps and particle entrapment in particle layers are responsible for the anomalous diffusion near the wall, while the subdiffusion in the core is related to the overall confinement by the channel walls. Copyright (C) EPLA, 2010