Two- and Three-Dimensional Flow of Grains through Apertures

Abstract

IN the course of experiments on the physics of the granular mass, the rate of discharge of three size grades of a dry, sharp sand was measured (a) from wide cylindrical vessels through circular and elliptical orifices, (b) from wide rectangular vessels through long slits. In both cases the apertures were situated on the central axis of a horizontal base. The mean particle sizes P of the size grades (18 × 36, 36 × 60, 44 × 120 British Standard mesh) were 0.053, 0.037, 0.020 cm. From the measured rate of discharge Q gm./sec., a mean linear velocity v cm./sec. was calculated as: A cm.2 being the area of the aperture and ρ the particle density in gm./cm.3. To find the true linear velocity of the particles from v it would be necessary to measure the bulk density of the flowing material at the orifice; this has not been done.