Velocity correlations and diffusion during sedimentation

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Journal Title
Journal ISSN
Volume Title
School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2001
Major/Subject
Mcode
Degree programme
Language
en
Pages
061505/1-7
Series
Physical Review E, Volume 63, Issue 6
Abstract
We study the dynamics of sedimenting non-Brownian particles under steady-state conditions in two-dimensional geometry. We concentrate on the autocorrelation functions of the velocity fluctuations and the corresponding memory functions and diffusion coefficients as functions of ΦV for small but finite Reynolds numbers. For the numerical simulations we have chosen the model of Schwarzer [Phys. Rev. E 52, 6461 (1995)] where a continuum liquid phase is coupled through Stokesian friction to a discrete particle phase with volume fraction ΦV. We find that the steady-state velocity fluctuations are spatially highly anisotropic and the correlation functions parallel to gravity have nonexponential time dependence similar to that of purely dissipative systems with strong interactions. The corresponding memory functions also show nontrivial behavior. Diffusion along the direction of gravity is much faster than perpendicular to it, with the anisotropy decreasing as either the Reynolds number or the volume fraction increases.
Description
Keywords
diffusion, sedimentation, non-Brownian particles, two-dimensional geometry, functions, velocity fluctuations
Other note
Citation
Kuusela, E. & Ala-Nissilä, Tapio. 2001. Velocity correlations and diffusion during sedimentation. Physical Review E. Volume 63, Issue 6. P. 061505/1-7. ISSN 1539-3755 (printed). DOI: 10.1103/physreve.63.061505.