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. (C) 2019 Published by Elsevier B.V.