The Experts below are selected from a list of 69 Experts worldwide ranked by ideXlab platform
M. A. Aguirre - One of the best experts on this subject based on the ideXlab platform.
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Granular flow through an aperture: Influence of obstacles near the outlet.
Physical Review E, 2020Co-Authors: M. G. Areán, Alejandro Boschan, Mario Cachile, M. A. AguirreAbstract:We study how the presence of obstacles in a confined system of monodisperse disks affects their discharge through an aperture. The disks are driven by a Horizontal Conveyor belt that moves at constant velocity. The mean packing fraction at the outlet decreases as the distance between the obstacles and the aperture decreases. The obstacles organize the dynamics of the stagnant zones in two characteristic behaviors that differ mainly in the magnitude of the fluctuations of the fraction of stagnant disks in the system. It is shown that the effective aperture is reduced by the presence of obstacles.
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Granular flow through an aperture: influence of the packing fraction.
Physical review. E Statistical nonlinear and soft matter physics, 2014Co-Authors: M. A. Aguirre, R. De Schant, Jean-christophe GéminardAbstract:For the last 50 years, the flow of a granular material through an aperture has been intensely studied in gravity-driven vertical systems (e.g., silos and hoppers). Nevertheless, in many industrial applications, grains are Horizontally transported at constant velocity, lying on Conveyor belts or floating on the surface of flowing liquids. Unlike fluid flows, that are controlled by the pressure, granular flow is not sensitive to the local pressure but rather to the local velocity of the grains at the outlet. We can also expect the flow rate to depend on the local density of the grains. Indeed, vertical systems are packed in dense configurations by gravity, but, in contrast, in Horizontal systems the density can take a large range of values, potentially very small, which may significantly alter the flow rate. In the present article, we study, for different initial packing fractions, the discharge through an orifice of monodisperse grains driven at constant velocity by a Horizontal Conveyor belt. We report how, during the discharge, the packing fraction is modified by the presence of the outlet, and we analyze how changes in the packing fraction induce variations in the flow rate. We observe that variations of packing fraction do not affect the velocity of the grains at the outlet, and, therefore, we establish that flow-rate variations are directly related to changes in the packing fraction.
Gabriel Lodewijks - One of the best experts on this subject based on the ideXlab platform.
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Speed control of belt Conveyors during transient operation
Powder Technology, 2016Co-Authors: Yusong Pang, Gabriel LodewijksAbstract:Abstract Belt Conveyors play an important role in continuous dry bulk material transport. Large scale belt Conveyor systems consume a considerable amount of electricity. The approach of controlling the belt speed in such a way that the belt's volumetric capacity is fully utilized under all operational conditions has been proven to significantly reduce the energy consumption of a belt Conveyor. Current research on speed control for belt Conveyors mainly focuses on the calculation and the prediction of possible energy savings. Few studies focus on the dynamics of belt Conveyors in transient operation. There are however no studies that describe the operation of speed controlled belt Conveyors during transient operation. This paper presents a three-step method that can be used to determine a proper way to accelerate a speed controlled belt Conveyor during transient operation. This method takes the potential risks in transient operation and the Conveyor dynamic performance into account. A case of Horizontal Conveyor system is studied and the three-step method is applied. In the case study, a predictor of the permitted maximum acceleration is calculated. Simulations with the predicted acceleration time are carried out to determine the acceleration operation and to analyse the Conveyor dynamics. The simulations are based on an existing finite element model of a belt Conveyor.
Jean-christophe Géminard - One of the best experts on this subject based on the ideXlab platform.
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Granular flow through an aperture: influence of the packing fraction.
Physical review. E Statistical nonlinear and soft matter physics, 2014Co-Authors: M. A. Aguirre, R. De Schant, Jean-christophe GéminardAbstract:For the last 50 years, the flow of a granular material through an aperture has been intensely studied in gravity-driven vertical systems (e.g., silos and hoppers). Nevertheless, in many industrial applications, grains are Horizontally transported at constant velocity, lying on Conveyor belts or floating on the surface of flowing liquids. Unlike fluid flows, that are controlled by the pressure, granular flow is not sensitive to the local pressure but rather to the local velocity of the grains at the outlet. We can also expect the flow rate to depend on the local density of the grains. Indeed, vertical systems are packed in dense configurations by gravity, but, in contrast, in Horizontal systems the density can take a large range of values, potentially very small, which may significantly alter the flow rate. In the present article, we study, for different initial packing fractions, the discharge through an orifice of monodisperse grains driven at constant velocity by a Horizontal Conveyor belt. We report how, during the discharge, the packing fraction is modified by the presence of the outlet, and we analyze how changes in the packing fraction induce variations in the flow rate. We observe that variations of packing fraction do not affect the velocity of the grains at the outlet, and, therefore, we establish that flow-rate variations are directly related to changes in the packing fraction.
Eric I. Corwin - One of the best experts on this subject based on the ideXlab platform.
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Eliminating friction with friction: 2D Janssen effect in a friction-driven system
Physical Review Letters, 2014Co-Authors: M. Yasinul Karim, Eric I. CorwinAbstract:The Janssen effect is a unique property of confined granular materials experiencing gravitational compaction in which the pressure at the bottom saturates with an increasing filling height due to frictional interactions with side walls. In this Letter, we replace gravitational compaction with frictional compaction. We study friction-compacted 2D granular materials confined within fixed boundaries on a Horizontal Conveyor belt. We find that even with high-friction side walls the Janssen effect completely vanishes. Our results demonstrate that gravity-compacted granular systems are inherently different from friction-compacted systems in at least one important way: vibrations induced by sliding friction with the driving surface relax away tangential forces on the walls. Remarkably, we find that the Janssen effect can be recovered by replacing the straight side walls with a sawtooth pattern. The mechanical force introduced by varying the sawtooth angle. can be viewed as equivalent to a tunable friction force. By construction, this mechanical friction force cannot be relaxed away by vibrations in the system.
Yusong Pang - One of the best experts on this subject based on the ideXlab platform.
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Speed control of belt Conveyors during transient operation
Powder Technology, 2016Co-Authors: Yusong Pang, Gabriel LodewijksAbstract:Abstract Belt Conveyors play an important role in continuous dry bulk material transport. Large scale belt Conveyor systems consume a considerable amount of electricity. The approach of controlling the belt speed in such a way that the belt's volumetric capacity is fully utilized under all operational conditions has been proven to significantly reduce the energy consumption of a belt Conveyor. Current research on speed control for belt Conveyors mainly focuses on the calculation and the prediction of possible energy savings. Few studies focus on the dynamics of belt Conveyors in transient operation. There are however no studies that describe the operation of speed controlled belt Conveyors during transient operation. This paper presents a three-step method that can be used to determine a proper way to accelerate a speed controlled belt Conveyor during transient operation. This method takes the potential risks in transient operation and the Conveyor dynamic performance into account. A case of Horizontal Conveyor system is studied and the three-step method is applied. In the case study, a predictor of the permitted maximum acceleration is calculated. Simulations with the predicted acceleration time are carried out to determine the acceleration operation and to analyse the Conveyor dynamics. The simulations are based on an existing finite element model of a belt Conveyor.