Discrete element simulations for granular material flows: effective thermal conductivity and self-diffusivity

1997 ◽  
Vol 40 (13) ◽  
pp. 3059-3068 ◽  
Author(s):  
M.L. Hunt
Keyword(s):  
Thermal Conductivity ◽  
Granular Material ◽  
Effective Thermal Conductivity ◽  
Discrete Element ◽  
Material Flows ◽  
Discrete Element Simulations

Kinetic Theory Analysis of Flow-Induced Particle Diffusion and Thermal Conduction in Granular Material Flows

1993 ◽  
Vol 115 (3) ◽  
pp. 541-548 ◽  
Author(s):  
S. S. Hsiau ◽  
M. L. Hunt
Keyword(s):  
Thermal Conductivity ◽  
Kinetic Theory ◽  
Granular Material ◽  
Effective Thermal Conductivity ◽  
Mixing Layer ◽  
Theory Model ◽  
Simple Shear Flow ◽  
Experimental Measurements ◽  
Material Flows ◽  
Analytical Relations

The present study on granular material flows develops analytical relations for the flow-induced particle diffusivity and thermal conductivity based on the kinetic theory of dense gases. The kinetic theory model assumes that the particles are smooth, identical, and nearly elastic spheres, and that the binary collisions between the particles are isotropically distributed throughout the flow. The particle diffusivity and effective thermal conductivity are found to increase with the square root of the granular temperature, a term that quantifies the kinetic energy of the flow. The theoretical particle diffusivity is used to predict diffusion in a granular-flow mixing layer, and to compare qualitatively with recent experimental measurements. The analytical expression for the effective thermal conductivity is used to define an apparent Prandtl number for a simple-shear flow; this result is also qualitatively compared with experimental measurements. The differences between the predictions and the measurements suggest limitations in applying kinetic theory concepts to actual granular material flows, and the need for more detailed experimental measurements.

scholarly journals Discharge of a granular silo under mechanical vibrations

2021 ◽  
Vol 249 ◽  
pp. 03037
Author(s):  
Arthur Pascot ◽  
Ghita Marouazi ◽  
Sébastien Kiesgen De Richter
Keyword(s):  
Shock Waves ◽  
Granular Material ◽  
Froude Number ◽  
Flow Rate ◽  
Relative Frequency ◽  
Discrete Element ◽  
Experimental Measurements ◽  
Mechanical Vibrations ◽  
Vibration Intensity ◽  
Discrete Element Simulations

In this paper, we study the flow rate of model granular material in a silo under the influence of mechanical vibrations. Experimental measurements and discrete element simulations (DEM) are performed in a quasi-2D silo. The influence on the flow rate of the opening size and the vibration applied on the entire silo is studied. Two distinct regimes are evidenced, governed by the Froude number Fr and the relative frequency Ω. In the first regime, a decreased flow rate is observed when increasing the vibration intensity. This behavior is explained by the presence of reorganizations induced by the vibration, leading to a more homogeneous but also slower flow. In the second regime, an increased flow rate is evidenced when increasing the vibration intensity. We find this behavior comes from the intermittent nature of the flow, where the flow rate is directly controlled by the propagation of shock waves all along the silo.

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