Prediction of granular mass discharge-rate and velocity of particles at the outlet of hoppers and silos is critical in industry which are handling and processing granular material. This work is focused on prediction of gravity driven granular mass discharge-rate through different orifice shapes (circular, square and triangular) with same opening area at discharge of a flat-bottomed cylindrical silo using DEM-based open-source software: LIGGGHTS. The basic idea behind this work was to use three orifice shapes and compare the steady-state (mean) mass discharge-rate (Q) for spherical glass beads, and calculation of Beverloo equation constants (k & C) and their dependence on orifice shape. Velocity contours along radial direction were plotted at different bed-heights showing the velocity distribution and dependence of velocity on orifice shape for funnel flows. (C) 2019 Elsevier B.V. All rights reserved.