Silo pressure predictions using discrete–element and finite–element analyses

Abstract

The storage of granular solids in silos provides many interesting problems concerning pressures and flow. It is difficult to obtain repeatable and trustworthy results from either experimental studies or theoretical modelling. Comparisons of the best computational models with experiments are, at best, weak, and provide little assurance of the accuracy of any existing predictive model. The study described here was undertaken to explore the predictions of different models on a set of simplified exercise silo problems. For these problems, no experimental results exist, but simpler tests for truth can be used.This paper reports briefly on an international collaborative study into the predictive capacity of current discrete-element and finite-element calculations for the behaviour of granular solids in silos. The predictions of one research group, however eminent, are often not regarded as authoritative by others, so a commonly agreed theoretical solution of simple silo exercises, using different computational models from research groups around the world, is a valuable goal. Further, by setting the same unbiased exercise for both finite elements and discrete elements, a better understanding was sought of the relationships between the two methods and of the strengths of each method in practical silo modelling.The key findings are outlined here from three of the challenge problems: filling a silo; discharge of granular solid from a flat-bottomed silo; and discharge from a silo with a tapered hopper. Both computational methods display considerable shortcomings for these difficult exercises. Different research groups make widely different predictions, even when the problem statement is very detailed. There is much scope for further comparative studies to identify the reasons why different models based on comparable assumptions can produce such varied predictions. Keywords: discharge from a silo; filling of a silo; granular solid; challenge calculations; numerical analyses; wall pressures † All the collaborators should properly be described as co-authors, but their number precludes this here.

Discrete element method modeling of corn-shaped particle flow in rectangular hopper

“…And at this time the over-pressure occurred in the height of 100 mm. Over-pressure is the pressure when the material discharging is larger than the material is stable at some height, and it is also observed by other researchers [18][19][20][21]. This over-pressure is very dangerous for hopper, so it should be carefulness when design hopper.…”

A simplified 3 D.O.F. model of A FEM model for seismic analysis of a silo containing elastic material accounting for soil–structure interaction

“…It is suggested, however, that not enough research currently exists to represent the issues fully. Contrary to this, there are a lot of studies about the effects of filling, discharging and/or the flow of bulk material when it comes to silos [2][3][4][5][6][7][8][9][10]. However, little information can be found about the seismic behavior of cylindrical silos.…”

Finite element investigation of the flow and stress patterns in conical hopper during discharge

“…FEM associated with elastoplastic constitutive theories can give satisfactory predictions of the internal stress and wall pressure in hoppers (Ooi and Rotter, 1990;Rotter et al, 1998;Goodey et al, 2003Goodey et al, , 2006Goodey and Brown, 2004;Vidal et al, 2006Vidal et al, , 2008Ding et al, 2013). However, its application to reproduce the flow conditions of granular material is usually not easy Sanad et al, 2001;Tejchman and Klisiński, 2001) and requires some particular schemes or treatments such as the re-meshing and re-zoning scheme (Sanad et al, 2001), adaptive meshing technique (Yang et al, 2011), viscoplastic granular fluid models (Haussler and Eibl, 1984;Karlsson et al, 1998;Elaskar et al, 2000;Böhrnsen et al, 2004), smoothed particle hydrodynamics (SPH) method (Sugino and Yuu, 2002), and material point method (MPM) (Wieckowski et al, 1999).…”

“…Consequently, it has been increasingly employed in recent decades to explore hopper behaviours, e.g. the mass discharge rate (Zhu and Yu, 2004;Anand et al, 2008), particle flow patterns (Ketterhagen et al, 2009) and internal bulk stresses (Langston et al, 1995;Rotter et al, 1998;Zhu and Yu, 2002). Nevertheless, it is known that to a large degree, DEM simulation can only deal with small-scale systems because it is computationally very demanding.…”