RADIAL AND AXIAL SEGREGATION OF GRANULAR MIXTURES IN THE ROTATING-DRUM GEOMETRY

2001 ◽  
Vol 04 (04) ◽  
pp. 469-479 ◽  
Author(s):  
SANJAY PURI ◽  
HISAO HAYAKAWA
Keyword(s):  
Surface Tension ◽  
Phenomenological Model ◽  
Dynamical Evolution ◽  
Rotating Drum ◽  
Effective Surface ◽  
Axial Segregation ◽  
Granular Mixtures ◽  
Sharp Interfaces

We formulate a phenomenological model for the dynamical evolution of granular mixtures in a rotating drum. In particular, we present a dynamical basis for an "effective surface tension," which penalizes sharp interfaces between regions enriched in different components of the mixture. We also present representative results which demonstrate that our model captures many experimental features for this problem.

scholarly journals Axial Segregation of Polydisperse Granular Mixtures in Rotating Drum Flows

Minerals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 915
Author(s):  
Elbasher Mohamed Elbasher Ahmed ◽  
Indresan Govender ◽  
Aubrey Njema Mainza
Keyword(s):  
Particle Simulation ◽  
Simulation Studies ◽  
Rotating Drum ◽  
Limited Mobility ◽  
Axial Segregation ◽  
Numerical Studies ◽  
Granular Mixtures ◽  
Common Thread ◽  
Long Time ◽  
Discrete Particle Simulation

Axial segregation of polydisperse granular mixtures in rotating drums have been observed in several experimental and discrete particle simulation studies reported in the literature. A common thread to both experimental and numerical studies is the formation of (alternating) bands which eventually coarsen in the long-time limit due to logarithmic merging. Models to explain the experimental observations are generally limited to bidisperse mixtures, and often unable to reproduce band coarsening. One such mechanism for bidisperse mixtures argues that the grains eventually diffuse into axial bands as a consequence of concentration fluctuations in the free surface layer caused by friction-limited mobility. We generalise this model to multi-species mixtures and show that the solution produces banding that evolves more complexly than binary mixtures, with sinusoidal-like variations of the band structure that evolves non-linearly in time. In addition, we successfully recover band coarsening with time—an observation that is generally difficult to reproduce, even experimentally. Contrary to literature findings, the configurations herein did not produce bands within bands for ternary and quaternary mixtures.

Particle shape-induced axial segregation of binary mixtures of spheres and ellipsoids in a rotating drum

2021 ◽  
Vol 235 ◽  
pp. 116491
Author(s):  
S.Y. He ◽  
J.Q. Gan ◽  
D. Pinson ◽  
A.B. Yu ◽  
Z.Y. Zhou
Keyword(s):  
Binary Mixtures ◽  
Particle Shape ◽  
Rotating Drum ◽  
Axial Segregation

scholarly journals The geometric axial surface profiles of granular flows in rotating drums

2021 ◽  
Vol 121 (5) ◽  
Author(s):  
Elbasher M.E. Ahmed ◽  
I. Govender ◽  
A. Mainza
Keyword(s):  
Free Surface ◽  
Surface Profile ◽  
Rotating Drum ◽  
Cross Sectional ◽  
Axial Segregation ◽  
Wide Range ◽  
Free Surface Profile ◽  
Axial Profile ◽  
Slurry Transport ◽  
Rotating Drums

SYNOPSIS A mechanistic description of axial segregation in rotating drum flows remains an open question. Consequently, optimal mixing of grinding balls and rocks for efficient breakage, maximum production of fines, and slurry transport is seldom achieved. Experimental and numerical studies of granular mixtures in rotating drums identify alternating axial bands that eventually coarsen in the long-term limit. Most models of axial segregation are limited to binary mixtures and cannot always predict the logarithmic coarsening effects observed experimentally. A key missing factor is a robust description of the axial free surface profile that is valid across a wide range of flow regimes. We present a practical model of the axial free surface profile by linking it to readily-derived geometric features of the cross-sectional S-shaped free surface profile. A parametric study shows good agreement with experimental measurements reported in the literature and heuristically valid trends. Keywords: rotating drum, granular flow, axial profile, comminution, mixing, segregation.

scholarly journals Reminiscent capillarity in subnanopores

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Irena Deroche ◽  
T. Jean Daou ◽  
Cyril Picard ◽  
Benoit Coasne
Keyword(s):  
Surface Tension ◽  
Porous Materials ◽  
Adsorption Energy ◽  
Phenomenological Model ◽  
Chemical Potential ◽  
Nanoporous Materials ◽  
Simulation Data ◽  
Pore Sizes ◽  
Fluid Surface ◽  
Molecular Scale

Abstract Fluids in large and small pores display different behaviors with a crossover described through the concept of critical capillarity. Here we report experimental and simulation data for various siliceous zeolites and adsorbates that show unexpected reminiscent capillarity for such nanoporous materials. For pore sizes D exceeding the fluid molecule size, the filling pressures p are found to follow a generic behavior kBT ln p ∼ γ/ρD where γ and ρ are the fluid surface tension and density. This result is rationalized by showing that the filling chemical potential for such ultra-small pores is the sum of an adsorption energy and a capillary energy that remains meaningful even for severe confinements. A phenomenological model, based on Derjaguin’s formalism to bridge macroscopic and molecular theories for condensation in porous materials, is developed to account for the behavior of fluids confined down to the molecular scale from simple parameters.

Oscillating sessile liquid marble - a tool to assess effective surface tension

2021 ◽  
pp. 127176
Author(s):  
Pradip Singha ◽  
Nhat-Khuong Nguyen ◽  
Jun Zhang ◽  
Nam-Trung Nguyen ◽  
Chin Hong Ooi
Keyword(s):  
Surface Tension ◽  
Effective Surface ◽  
Liquid Marble
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