“…The basic action taken to improve the flow and unloading is to properly design the geometry of the tank [26], e.g., wedge [27], conical [28], angled [29], hour-glass, clepsydra [30], pyramidal [31] tilted [32], curved shaped [33] and its outlet [34]. The hopper should be adequately matched, taking into account the type of material, the nature of its flow and its properties [35] like grain size [36] and shape [37], vertical pressures and compressive friction force [38] or flow properties [39].…”