Non-local effects in intermediate granular avalanching flows

In this work we showed that photoelastic analysis allows the quantification of rheologies in an intermediate chute flow. We characterize stresses and velocities in a flow layer with regions below and above the yield ratio mu_s. We compare our experimental results with a nonlocal rheology. Preliminary results show that the timescale over which the force chains decorrelate is strongly associated with the inverse of the fluidity, a viscosity-like quantity. This provides a physical interpretation of its particle-scale origins.