Numerical effects derived from en masse filling of agricultural silos in DEM simulations
AUTHOR(S)
A. Ramirez, C. González-Montellano, F.Ayuga, J.M. Fuentes
PUBLISHER
Elsevier
SOURCE
Computers and Electronics in Agriculture
YEAR
ABSTRACT
The discrete element method (DEM) is a numerical technique widely used to study the behaviour of granular materials. It is commonly employed to determine the pressures generated by these materials on storage silo walls, although the computational costs associated with the simulation of real cases can be very high, a consequence of the number of particles that must be taken into account. Simplifications that can reduce calculation times are therefore usually sought. One such simplification is the contemplation of en masse filling rather than the progressive filling that typically takes place in silos. In en masse filling, all the particles involved in a simulation are simultaneously generated inside the recipient at the beginning of the procedure. They are then allowed to virtually fall under the effect of gravity until a static equilibrium is reached, indicating the end of the silo filling phase.The present work examines the effects on DEM-predicted silo wall pressures during the filling and emptying phases derived from the use of this filling procedure. Separate simulations were performed using glass beads or maize as the storage material, and using either the en masse or progressive filling procedures. The predictions of the pressures generated in each simulation were compared with one another and, at a qualitative level, with those theoretically expected using standard EN 1991-4 (2006). The results showed the en masse procedure to notably reduce computation times, although the predictions of the pressures generated during the filling phase can be erroneous. This is due to the impossibility of particle reordering imposed by en masse filling. This provokes the development of unreal contact forces that deviate pressure predictions from those expected.
KEYWORDS
Discrete element method, En masse filling, Mobilised friction, Pressures, Progressive filling, Silo