Different shear regimes in the dense granular flow in a vertical channel

The steady dense granular flow in a vertical channel bounded by flat frictional walls one horizontal direction and with periodic boundary conditions the other directions is studied using discrete element method. shape of scaled velocity profile characterized quantitatively universal exponential function, ratio maximum slip velocities independent average volume fraction $\bar {\phi }$ width $W$ . For sufficiently wide channels, increase proportional to $\sqrt {W}$ , thickness shearing zones increases There are four flow, each distinct dynamical properties. no shear plug zone at centre, but there particle agitation, $\phi$ lower than random close packing $\phi _{rcp}$ In adjoining zone, greater for arrested dynamics _{ad} = 0.587$ temperature rate depend on stiffness. Adjacent loose where < \phi _{ad}$ Here, properties do not stiffness, constitutive relations well described hard-particle models. rheology similar down an inclined plane. high sharp decrease wall about two diameters, angular different from material rotation due presence wall.