Dynamics of size segregation of granular materials by shaking

1998 ◽  
Vol 20 (9) ◽  
pp. 1443-1448 ◽  
Author(s):  
Zhu Jiongming ◽  
Zhou Binglu ◽  
Wang Bin
Keyword(s):  
Granular Materials ◽  
Size Segregation

Molecular Dynamics Study of Cohesionless Granular Materials: Size Segregation by Shaking

1993 ◽  
Vol 07 (09n10) ◽  
pp. 1865-1872 ◽  
Author(s):  
Toshiya OHTSUKI ◽  
Yoshikazu TAKEMOTO ◽  
Tatsuo HATA ◽  
Shigeki KAWAI ◽  
Akihisa HAYASHI
Keyword(s):  
Molecular Dynamics ◽  
Steady State ◽  
Specific Gravity ◽  
Pressure Gradient ◽  
Granular Materials ◽  
Buoyancy Force ◽  
Temporal Evolution ◽  
Particle Radius ◽  
Size Segregation ◽  
Increasing Function

The Molecular Dynamics technique is used to investigate size segregation by shaking in cohesionless granular materials. Temporal evolution of the height h of the tagged particle with different size and mass is measured for various values of the particle radius and specific gravity. It becomes evident that h approaches the steady state value h∞ independent of initial positions. There exists a threshold of the specific gravity of the particle. Below the threshold, h∞ is an increasing function of the particle size, whereas above it, h∞ decreases with increasing the particle radius. The relaxation time τ towards the steady state is calculated and its dependence on the particle radius and specific gravity is clarified. The pressure gradient of pure systems is also measured and turned out to be almost constant. This suggests that the buoyancy force due to the pressure gradient is not responsible to h∞.

Application of simulation technologies in the analysis of granular material behaviour during transport and storage

2005 ◽  
Vol 219 (1) ◽  
pp. 43-52 ◽  
Author(s):  
P Chapelle ◽  
N Christakis ◽  
J Wang ◽  
N Strusevich ◽  
M. K. Patel ◽  
...  
Keyword(s):  
Granular Material ◽  
Granular Materials ◽  
Large Scale ◽  
Computational Models ◽  
Research Programme ◽  
Size Segregation ◽  
Materials Handling ◽  
Simulation Tools ◽  
And Storage

Problems in the preservation of the quality of granular material products are complex and arise from a series of sources during transport and storage. In either designing a new plant or, more likely, analysing problems that give rise to product quality degradation in existing operations, practical measurement and simulation tools and technologies are required to support the process engineer. These technologies are required to help in both identifying the source of such problems and then designing them out. As part of a major research programme on quality in particulate manufacturing computational models have been developed for segregation in silos, degradation in pneumatic conveyors, and the development of caking during storage, which use where possible, micro-mechanical relationships to characterize the behaviour of granular materials. The objective of the work presented here is to demonstrate the use of these computational models of unit processes involved in the analysis of large-scale processes involving the handling of granular materials. This paper presents a set of simulations of a complete large-scale granular materials handling operation, involving the discharge of the materials from a silo, its transport through a dilute-phase pneumatic conveyor, and the material storage in a big bag under varying environmental temperature and humidity conditions. Conclusions are drawn on the capability of the computational models to represent key granular processes, including particle size segregation, degradation, and moisture migration caking.

scholarly journals Modelling size segregation of granular materials: the roles of segregation, advection and diffusion

2014 ◽  
Vol 741 ◽  
pp. 252-279 ◽  
Author(s):  
Yi Fan ◽  
Conor P. Schlick ◽  
Paul B. Umbanhowar ◽  
Julio M. Ottino ◽  
Richard M. Lueptow
Keyword(s):  
Granular Materials ◽  
Dimensionless Parameter ◽  
System Size ◽  
Quantitative Agreement ◽  
Particle Sizes ◽  
Control Parameters ◽  
Size Segregation ◽  
Particle Segregation ◽  
Kinematic Measures ◽  
And Diffusion

AbstractPredicting segregation of granular materials composed of different-sized particles is a challenging problem. In this paper, we develop and implement a theoretical model that captures the interplay between advection, segregation and diffusion in size bidisperse granular materials. The fluxes associated with these three driving factors depend on the underlying kinematics, whose characteristics play key roles in determining particle segregation configurations. Unlike previous models for segregation, our model uses parameters based on kinematic measures from discrete element method simulations instead of arbitrarily adjustable fitting parameters, and it achieves excellent quantitative agreement with both experimental and simulation results when applied to quasi-two-dimensional bounded heaps. The model yields two dimensionless control parameters, both of which are only functions of control parameters (feed rate, particle sizes, and system size) and kinematic parameters (diffusion coefficient, flowing layer depth, and percolation velocity). The Péclet number, $\mathit{Pe}$, captures the interplay of advection and diffusion, and the second dimensionless parameter, $\Lambda $, describes the interplay between segregation and advection. A parametric study of $\Lambda $ and $\mathit{Pe}$ demonstrates how the particle segregation configuration depends on the interplay of advection, segregation and diffusion. The model can be readily adapted to other flow geometries.

scholarly journals Shear-driven size segregation of granular materials: Modeling and experiment

2010 ◽  
Vol 81 (5) ◽  
Author(s):  
Lindsay B. H. May ◽  
Laura A. Golick ◽  
Katherine C. Phillips ◽  
Michael Shearer ◽  
Karen E. Daniels
Keyword(s):  
Granular Materials ◽  
Size Segregation ◽  
Materials Modeling

scholarly journals Size segregation of irregular granular materials captured by time-resolved 3D imaging

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Parmesh Gajjar ◽  
Chris G. Johnson ◽  
James Carr ◽  
Kevin Chrispeels ◽  
J. M. N. T. Gray ◽  
...  
Keyword(s):  
Granular Materials ◽  
Complex Dynamics ◽  
Experimental Studies ◽  
Vertical Axis ◽  
Time Lapse ◽  
Brazil Nut ◽  
Size Segregation ◽  
Time Resolved ◽  
Brazil Nuts ◽  
Brazil Nut Effect

AbstractWhen opening a box of mixed nuts, a common experience is to find the largest nuts at the top. This well-known effect is the result of size-segregation where differently sized ‘particles’ sort themselves into distinct layers when shaken, vibrated or sheared. Colloquially this is known as the ‘Brazil-nut effect’. While there have been many studies into the phenomena, difficulties observing granular materials mean that we still know relatively little about the process by which irregular larger particles (the Brazil nuts) reach the top. Here, for the first time, we capture the complex dynamics of Brazil nut motion within a sheared nut mixture through time-lapse X-ray Computed Tomography (CT). We have found that the Brazil nuts do not start to rise until they have first rotated sufficiently towards the vertical axis and then ultimately return to a flat orientation when they reach the surface. We also consider why certain Brazil nuts do not rise through the pack. This study highlights the important role of particle shape and orientation in segregation. Further, this ability to track the motion in 3D will pave the way for new experimental studies of segregating mixtures and will open the door to even more realistic simulations and powerful predictive models. Understanding the effect of size and shape on segregation has implications far beyond food products including various anti-mixing behaviors critical to many industries such as pharmaceuticals and mining.

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