Title: Regimes Transition Behavior in Wide Inclined Granular Flows

Author (Talk): Pouria Hajizadeh, UNIVERSITY OF ROCHESTER

Abstract:

Granular flows down a wide incline can exhibit distinct flow behavior, ranging from a solid-like plug zone to a fluid-like shear zone. In this work, we investigate the effect of different granular system parameters on gravity-driven granular flows in wide inclines using discrete element method simulations. We observe that a shear layer consistently develops near the bottom boundary, with a characteristic length of approximately 6 particle diameters (6d), while the upper region behaves as plug flow. We estimate the shear layer length using the critical microscopic non-dimensional granular temperature, \Delta_c. This behavior remains robust across different granular system sizes, including pile height (H) and mean particle diameter (d), and over a small range of inclination angles close to the repose angle. Moreover, the 6d shear layer is consistent with the length scale associated with the Beverloo law's prediction for the minimum effective orifice length in funnel flow. On the other hand, variation in particle-particle and particle-base friction coefficients is found to disrupt the coexistence of flow regimes. We find that nonlocal \mu(I, \Delta) rheology better captures the plug flow, whereas local \mu(I) rheology better describes the shear flow near the base. Overall, this study clarifies the coexistence of plug and shear regimes in wide-incline granular flows with a slip base and highlights the rheological models that most effectively capture the corresponding flow structure and transition behavior.