Numerical simulations of two-dimensional stationary dense granular flows are performed. We check that the system obeys the $h_{stop}$ phenomenology. Focusing on the spatial correlations of the instantaneous velocity fluctuations of the grains, we give evidence of the existence of correlated motion over several grain diameters in the bulk of the flow. Investigating the role of contact friction and restitution, we show that the associated typical length scale $\lambda$ is essentially independent of the grain properties. Moreover, we show that $\lambda$ is not controlled by the packing compacity. However, in agreement with previous experimental work, we observe that the correlation length decreases with the shear rate. Computing the flows inertia number $I$, we show a first-order dependence of $\lambda$ on $I$.

• Received 14 December 2007

DOI:https://doi.org/10.1103/PhysRevE.77.051304