DEM simulation of the pressure distribution and flow pattern in a model grain silo with an annular segment attached to the wall

Abstract

A study was conducted to simulate numerically the effects of internal inserts in the form of an annular segment attached to the wall of a cylindrical container. A series of DEM simulations were performed with an assembly of 200,000 spherical particles with a mean diameter of 3.79 mm (dp) filling a 0.16 m diameter and 0.48 m high cylindrical container. The internal insert was a full ring attached to the wall at height-to-diameter ratios (h/D) of 0.31, 0.62, and 0.95 with widths of 3, 6, 9, and 12dp. Simulations were also performed for h/D = 0.62 and width 6dp in which ring segments had partial angular extents to evaluate the load asymmetry. The commencement of discharge resulted in a sharp increase of the bending moment to a maximum value of 0.65 N m, which was found for a third and a half-circle obstruction. This value is slightly higher than that (0.6 N m) found in the worst case of non-axial discharge and, thus, should be considered structurally dangerous. The dimensionless bending moment was calculated and values were of 0.0814 and 0.099 for simulation and experiment respectively. Considering the significant differences between the conditions in the real system, and the numerical model, this result may be treated as being in reasonable agreement. It was proposed that the dangerous asymmetry of silo wall loads generated by eccentric discharge may be minimised or eliminated by the suitable placement of an appropriate annular insert above the silo floor.