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We experimentally design an integrated system composed of a conveyor belt and a posts array, which can simultaneously implement the function of size separation and transportation of disk particles. Differently sized particles through the post array exhibit two types of distinct migration modes that are responsible for the size separation. Furthermore, the dividing line between the two migration modes depends on the critical radius found in experiment. The relationship between the separation efficiency and the length of the post array and the packing fraction of particles is investigated quantitatively. Finally, a simplified model is proposed to predict a critical particle radius which is verified to be in accordance with experimental measurements. This research has a potential application prospect in some fields of industry.

Horizontal flow of discrete objects through a bottleneck is prevalent and important in nature and industry. In this paper, we experimentally investigate the frictional effect of the bottom wall on the flow rate of granular particles passing through an aperture on a conveyor belt, since the bottom wall is always assumed to be trivial and the issue remains elusive. The flow rate monotonically increases with the coefficient of friction, finally approaching a saturation plateau. The bottom wall has an obvious effect on the flow rate. We show that the lateral motion of particles on both sides of the aperture, which is influenced by the coefficient of friction and can be converted into an effective aperture width, is responsible for the variation of the longitudinal flow rate. Our findings may provide a new way to manipulate the horizontal flow rate, particularly for the case where the aperture has to be fixed.

We experimentally present three methods for improving flow rate of disks driven through an aperture on a conveyor belt: modifying a flat bottom wall, tuning an initial packing configuration and the combination of both above, when the aperture and conveyor belt velocity cannot be altered. Improvements of up to 15.6% are reported. By measuring the packing density, vertical and horizontal velocity profiles in the flow of disks just before the aperture for various cases, we conclude that flow rate is mainly determined by the vertical velocity in each of these three methods. In addition, we qualitatively discuss that the horizontal velocity has two adverse effects on the vertical velocity. Potentially, this research can shed light on traffic flow or emergency evacuation of crowds.