Surface flows of granular materials find several important applications in both nature as well as industry. The effect of sidewalls on such flows is known to be large. Here, we study the rheology of such flows on a quasi two-dimensional heap without sidewalls, at different mass flow rates. It is seen that the surface angle of the heap, for all the mass flow rates, is the same and corresponds to the neutral angle. System variables such as the velocity, volume fraction and stresses are reported as a function of depth from the free surface of the heap. The friction coefficient and volume fraction are also studied as a function of the scaled local shear rate and these are also found to be independent of the mass flow rate. The behaviour observed in the present work is different from that reported in previous studies of surface flows with side walls.

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