Many materials will not flow in hoppers with such shallow hopper chute angle. In order to avoid excessively tall structures, it is quite common to have multiple discharge ports from multiple conical sections with a much steeper chute angle. Multiple discharge ports can also be used if large ranges of flow rates are required or if the material needs to flow to different destinations.

DEM simulations have been performed for a cylindrical four-port hopper, 4 m high and 1.5 m in diameter. The four discharge ports each have a diameter of 250 mm and a conical chute angle of 60 degrees. The particles are uniformly distributed in size between 25 and 60 mm. For this case, 70,000 particles are required to fill the hopper, and particles discharge through all four ports. The figure below right shows a cutaway view of the discharge from the four-port hopper.

Cutaway view of the discharging of particles (coloured in layers) from cylindrical single-port (left) and four-port (right) hoppers.

DEM modelling can be used to assess the effect of using only some of the discharge ports and to assess the impact of various combinations of these on the forces applied by the flowing granular material to the hopper structure. The existence of stagnant regions can also be identified along with other impediments to flow, which are much more common in multiple discharge hoppers.