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The CANAsand constitutive law in conjunction with the ID technique is used to study the flow phenomenon in a cohesionless granular medium placed between two parallel, rough vertical walls. It is shown that the development of flow is influenced by the geometry of the case. However the main factor is the void ratio of the medium: i.e. arching will prevent the free flow of the material if its void is close to the compact state. The study is extended to cover the axisymmetric situation. Here the flow of bulk solids through a circular opening at the base of a cylindrical tank is examined.