  The properties of confined granular flows are studied through discrete
numerical simulations. Two types of flows with different boundaries are
compared: (i) gravity-driven flows topped with a free surface and over a base
where erosion balances accretion (ii) shear-driven flows with a constant
pressure applied at their top and a bumpy bottom moving at constant velocity.
In both cases we observe shear localization over or/and under a creep zone. We
show that, although the different boundaries induce different flow properties
(e.g. shear localization of transverse velocity profiles), the two types of
flow share common properties like (i) a power law relation between the granular
temperature and the shear rate (whose exponent varies from 1 for dense flows to
2 for dilute flows) and (ii) a weakening of friction at the sidewalls which
gradually decreases with the depth within the flow.
