Subtle order in settling suspensions*
B. J. Ackerson, X. L. Lei, and P. Tong
Department of Physics, Oklahoma State University, Stillwater,
OK 74078-3072, USA
Abstract: A dilute suspension of uniform, non-Brownian spheres
settles slowly in a viscous solvent. The initially well-mixed system
showing Poisson or random occupancy statistics evolves to a system having
reduced number fluctuations, but otherwise appearing random. The reduced
number fluctuations are consistent with recent measurements of velocity
fluctuations in settling suspensions. These experimental results test
the assumptions leading to the theoretical predictions by Calflisch
and Luke that the velocity fluctuations increase without limit with
increasing sample dimension. The theoretical prediction assumes Poisson
occupation statistics contrary to our observations.
* Plenary lecture presented at the 27th International
Conference on Solution Chemistry, Vaals, The Netherlands, 26-31 August
2001. Other presentations are published in this issue, pp. 1679-1748.
Back to Contents for access to full text
Page last modified 13 February 2002.
Copyright © 2002 International Union of Pure and Applied Chemistry.
Questions or comments about IUPAC, please contact, the Secretariat.
Questions regarding the website, please contact web