Experimental and numerical investigation on the influence of particle shape and shape approximation on hopper discharge using the discrete element method

Determination and Validation of Discrete Element Model Parameters of Soybeans with Various Moisture Content for the Discharge Simulation from a Cylindrical Model Silo

This study investigates the physical parameters that affect the flow patterns of soybeans with various moisture content (12% to 60%) at varying orifice sizes (20, 40, and 60 mm) in a cylindrical silo. The flow conditions required to obtain a steady mass flow during discharge were evaluated via experiments and three-dimensional discrete element method (DEM) simulation. The discharged mass flow rates at different flow conditions provided the critical size of the orifice. If the reduced diameter (Dred) of an orifice is >5.59, the flow showed a steady state. Based on the mass flow index (MFI), the flow patterns at 40% and 60% moisture content at 40 and 60 mm orifice sizes, respectively, showed funnel flows. although these flow conditions were satisfied to maintain a steady flow. The maximum wall pressure for the funnel flow showed the location of the interlocking phenomenon where the stagnant zone began during discharging. DEM simulation was validated through the mass profiles using the parameters obtained by the experiments. This study demonstrates that the experimental and analytical results with DEM simulation predict the flow behaviors of soybeans well at various moisture contents. These results are useful for designing silos for continuous food processing.

DEM study of the angle of repose and porosity distribution of cylindrical particles with different lengths

Effect of the length of cylindrical particle on repose angle and porosity of a pile was numerically studied using discrete element method. The variation of repose angle and porosity with coefficient of sliding and rolling friction were also discussed. The results shown that compared with sphere particle, the bottom size of cylindrical pile is smaller, while the height of cylinder pile is larger and the heap is steeper. With the increase of the length of cylinder, the contour line of the pile becomes steep, and the angle of repose increases. The repose angle shows a positive correlation with coefficient of sliding and rolling friction. The porosity increases with the increase of the length of cylinders. The trends of porosity are basically consist with that of repose angle, and with increase of friction coefficient, the average porosity increases.

Discrete element simulation of the charge in the hopper of a blast furnace, calibrating the parameters through an optimization algorithm

The purpose of this study is to simulate the distribution of a coarse granular material discharged in a hopper via a conveyor belt. This simulation is intended to be a model calibration for an optimization that will be later performed to obtain a proper material distribution device. From the hopper, the material is discharged in a blast furnace. Hence, achieving an adequate distribution in the hopper is crucial, since that distribution is directly linked to how the material spreads in the blast furnace, and this heavily influences the efficiency of the whole steel-making process. The apparatus is modeled by online three dimensional Computer-Aided Design software Onshape. Rocky DEM, a Computer-Aided Engineering software based on Discrete Element Method, is used to simulate the charge. The parameters of the numerical model are calibrated through an optimization algorithm. This phase is realized thanks to the optimization platform modeFRONTIER, using an algorithm that exploits meta-models to reduce the computational time of the optimization. By comparing the simulated results with the visual data obtained from blast furnace plant, the goal is to validate the model and to better understand the behavior of the whole charging process.

Effect of grain shape on the dynamics of granular materials in 2D rotating drum

We experimentally investigate the effect of the grain shape on the flow of granular material. The grain shape is modified to highlight the effect of grain circularity on granular flow in a 2D rotating drum. Using a laser cutter, we create particles with decreasing circularity. We observe that the effect of grain shape depends on the rotation speed of the drum. For high rotation speed, granular flow is influenced by the packing’s dilatancy whereas, at low rotation speed, packing fraction seems to influence flowing dynamics. We link these two measurements to grain shape in order to explain its effect on granular flow.

Flow of anisometric particles in a quasi-two-dimensional hopper

The stationary flow field in a quasi-two-dimensional hopper is investigated experimentally. The behavior of materials consisting of beads and elongated particles with different aspect ratio is compared. We show, that while the vertical velocity in the flowing region can be fitted with a Gaussian function for beads, in the case of elongated grains the flowing channel is narrower and is bordered with sharper velocity gradient. For this case, we quantify deviations from the Gaussian velocity profile. Relative velocity fluctuations are considerably larger and slower for elongated grains.