Résumé
We analyze the shear flow of dense granular materials composed of circular particles andimmersed in a viscous fluid by means of molecular dynamics simulations interfaced with theLattice Boltzmann Method. A homogeneous flow of the suspension is obtained through periodicboundary conditions andby directly applying a confining pressure on the granular phase and shearing the fluid phase.The stead-state rheology may be described in terms of effective friction coefficient and packingfraction of the suspension as a function of the ratio of viscous shear stress to confining pressure(frictional description), on one hand, and in terms of normal and shear viscosities of thesuspension as a function of the packing fraction (viscous description), on the other hand. Weshow that the simulation data are consistent with both descriptions and in close agreement withthe corresponding scaling laws observed in recent experiments. This dual description impliesthat the friction coefficient is a function only of the packing fraction. Indeed, we find that all ourfriction data versus packing fraction for different values of fluid viscosity collapse on the samecurve.