(40b) Discrete and Continuum Modeling of Granular Flow in Silo Discharge

The discharging of granular materials from a flat-bottomed silo is simulated by using continuum modeling and 3D discrete element method (DEM). The predictive abilities of three commonly used frictional viscosity models (Schaeffer, S-S and μ(I)) are evaluated by comparing with DEM data. Both the funnel flow pattern (type C) and the semi-mass flow pattern (type B) predicted by DEM simulations can be successfully represented when Schaeffer or μ(I) model is adopted, whereas S-S model gives a consistent type B flow pattern. Moreover, all the three models over-estimate the discharge rate when compared to DEM result. By checking the profiles of solids volume fraction and vertical velocity right above the outlet, it is found that the larger discharge rates given by Schaeffer and μ(I) model is due to the over-estimation of volume fraction, while the deviation appeared in S-S model stems from the failure in predicting both solid vertical velocity and volume fraction