Particle discharge from a flat bottom hopper has been performed employing a Discrete Element Model with Multi-sphere particles[1]. A semi-two dimensional hopper has been prepared by using 3-dimensional particles in a vertical layer. Particulate assemblies comprising 5000 particles of different aspect ratios ranging from 1 to 4 have been created using some non-overlapping spheres in order to investigate the effect of particle shape on bed structure and flow characteristics of particles. The results showed a distribution of solid fraction within each bed, with the closest distribution to the normal distribution for the beds of elongated particles. The localised densely packed areas have been separated by voids caused by bridging of particles in the beds. Simulation results on silo discharge showed that the behaviour of beds of spherical particles was quite different from that of non-spherical particles. Spherical particles moved individually during flow and rolled over each other, resulting in a lower resistance to shear with a fluid-like flow, whereas elongated particles exhibited a stronger shear due to interlocking between particles, resulting in a flow, like a breaking continuum. This unique behaviour of spherical particles caused a higher flow rate than non-spherical particles. The formation of arching has been also simulated by the DE model. A qualitative correlation between the frequency of arching and aspect ratio has been recognised. More arching occurred as the aspect ratio of particles increased. It has been observed that while the bed of spherical particles sheared vertically, an inclined shearing observed for the beds of non-spherical particles. The simulation of the filling process and repose tests for frictional spherical and non-spherical particles showed that the shape of heap could be affected by particle shape, as well as drop height and filling stream rate. It has been found that the particle shape dominated the effect of the other two factors i.e. a steeper heap has been found for non-spherical particles than spherical particles even though the drop height was higher for non-spherical particles. It can therefore be concluded that the results obtained from the DEM models with spherical particles cannot be generalised to real material comprising non-spherical particles.

Particle discharge from a flat bottom hopper has been performed employing a Discrete Element Model with Multi-sphere particles[1]. A semi-two dimensional hopper has been prepared by using 3-dimensional particles in a vertical layer. Particulate assemblies comprising 5000 particles of different aspect ratios ranging from 1 to 4 have been created using some non-overlapping spheres in order to investigate the effect of particle shape on bed structure and flow characteristics of particles. The results showed a distribution of solid fraction within each bed, with the closest distribution to the normal distribution for the beds of elongated particles. The localised densely packed areas have been separated by voids caused by bridging of particles in the beds. Simulation results on silo discharge showed that the behaviour of beds of spherical particles was quite different from that of non-spherical particles. Spherical particles moved individually during flow and rolled over each other, resulting in a lower resistance to shear with a fluid-like flow, whereas elongated particles exhibited a stronger shear due to interlocking between particles, resulting in a flow, like a breaking continuum. This unique behaviour of spherical particles caused a higher flow rate than non-spherical particles. The formation of arching has been also simulated by the DE model. A qualitative correlation between the frequency of arching and aspect ratio has been recognised. More arching occurred as the aspect ratio of particles increased. It has been observed that while the bed of spherical particles sheared vertically, an inclined shearing observed for the beds of non-spherical particles. The simulation of the filling process and repose tests for frictional spherical and non-spherical particles showed that the shape of heap could be affected by particle shape, as well as drop height and filling stream rate. It has been found that the particle shape dominated the effect of the other two factors i.e. a steeper heap has been found for non-spherical particles than spherical particles even though the drop height was higher for non-spherical particles. It can therefore be concluded that the results obtained from the DEM models with spherical particles cannot be generalised to real material comprising non-spherical particles.

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