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Diffusion, mixing, and segregation in confined granular flows
Author(s) -
Fry Alexander M.,
Umbanhowar Paul B.,
Ottino Julio M.,
Lueptow Richard M.
Publication year - 2019
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.16494
Subject(s) - diffusion , overburden , overburden pressure , shear (geology) , mechanics , chemistry , mixing (physics) , discrete element method , thermodynamics , geotechnical engineering , geology , materials science , physics , composite material , quantum mechanics
Discrete element method simulations of confined bidisperse granular shear flows elucidate the balance between diffusion and segregation that can lead to either mixed or segregated states, depending on confining pressure. Results indicate that the collisional diffusion is essentially independent of overburden pressure. Because the rate of segregation diminishes with overburden pressure, the tendency for particles to segregate weakens relative to the remixing of particles due to collisional diffusion as the overburden pressure increases. Using a continuum approach that includes a pressure‐dependent segregation velocity and a pressure‐independent diffusion coefficient, the interplay between diffusion and segregation is accurately predicted for both size and density bidisperse mixtures over a wide range of flow conditions when compared to simulation results. Additional simulations with initially segregated conditions demonstrate that applying a high enough overburden pressure can suppress segregation to the point that collisional diffusion mixes the segregated particles. © 2018 American Institute of Chemical Engineers AIChE J , 65: 875–881, 2019