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Field-flow fractionation

Published online by Cambridge University Press:  20 April 2006

Ronald Smith
Ronald Smith
Affiliation:
Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Silver Street, Cambridge CB3 9EW
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Abstract

If different contaminant species are subject to different transverse drift rates (e.g. gravitational settling), then there is a tendency for the species to separate out. The efficiency of this separation depends upon the relative shapes of the longitudinal concentration distributions. Jayaraj & Subramanian (1978) have drawn attention to the disparity between their computed skew concentration distributions and the symmetric Gaussian distributions predicted by one-dimensional diffusion models. Here it is shown that a one-dimensional delay-diffusion model yields suitably skew predictions. The model equation is used to investigate the extent to which the separation of different contaminant species can be improved by pre-treating the sample (i.e. allowing differential drift) in a stationary fluid before being eluted into the shear flow. Pretreatment is found to be very effective for plane Poiseuille flow but not for the thermogravitational columns.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 129 , April 1983 , pp. 347 - 364
Copyright
© 1983 Cambridge University Press

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