Flow regimes of a fluid driven granular suspension

We discuss molecular dynamics simulations of a granular suspension driven in a channel by an embedding fluid. The flow has three different regimes: it is disordered at small packing fractions, ; above a transition point, TeX , flows becomes ordered in layers, but only in a fraction of samples; at higher TeX , if ordering is avoided, jamming is also encountered. In the disordered flow regime the velocity profile is power law, consistent with an Ostwald-de Waele constitutive relation. In the ordered regime, flow is concentrated in the bulk in a nearly solid plug having a flat velocity profile, with narrow shear regions at the boundaries. Interestingly, velocity fluctuations are approximately linear in the velocity in all regimes.