In this study, four calibration experiments were conducted for the DEM validation: filling of a model silo, confined compression in a cylinder, rod penetration into a granular bulk and silo discharging through an outlet. DEM simulations were conducted using two commercial software: PFC3D and EDEM, the latter being the DEM software that originated from Edinburgh University. A set of 8 benchmark tests were carried out to validate the codes and to evaluate the fundamental aspects of DEM. Following that, a large number of DEM simulations were conducted and comparisons between DEM simulations and experiments were made. For corn grains: the study shows that 4-sphere representation together with the measured corn properties produced satisfactory match with experiments for silo filling (normal wall pressure distribution), confined compression (normal wall pressure distribution, load transfer to boundary surfaces, and silo design parameter <i>K</i> and <i>m</i>), rod penetration (force-displacement response) and silo discharge (mass flow rate and angle of repose). For glass beads: the DEM simulations also gave good agreement with experiments for silo filling (normal wall pressure distribution), confined compression (normal wall pressure distribution, load transfer to boundary surfaces), rod penetration (force-displacement response) and silo discharge (mass flow rate). These findings provide sound verification that DEM is capable of producing quantitative predictions of the problems studied. They also suggest that very accurate representation of the non-spherical particle shape may not be necessary to produce satisfactory predictions and capturing the linear dimensions of a particle may be adequate. Two DEM results that produced larger discrepancies with experiments are filling density (~17% lower for corn grains and ~8% lower for glass beads) and loading stiffness (stiffer response). Plausible explanations for these are given in this thesis, which should be explored further.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:643168 |
| Date | January 2006 |
| Creators | Chung, Yun-Chi |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/13394 |
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