The region of flow when discharging granular materials from bin-hopper systems

Abstract A theory is developed, equally applicable to cohesive and non-cohesive materials, which gives the shape of the boundary of the flow region in the transition from a bin section with vertical parallel walls to a hopper with converging plane walls. The theory was tested for an angular non-cohesive granular material with an angle of internal friction of 35·5°. Good agreement between experiment and theory was obtained but small consistent differences were noted. An experimental method was also devised to define the boundary of the region of fast moving material.