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Effect of boundary absorption upon longitudinal dispersion in shear flows

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

Boundary absorption causes a depletion of contaminant. Since the boundary tends to be the region of lowest velocity and of strongest shear, the remaining contaminant experiences on average an increased advection velocity, a reduced rate of shear dispersion, and a tendency to develop skewness towards the rear. Here it is shown how all these effects can be incorporated into a delay-diffusion description of the longitudinal dispersion process (Smith 1981). It is the accurate reproduction of the skewness that permits a delay-diffusion equation to become applicable at an earlier stage than the more conventional diffusion-equation models for longitudinal dispersion, and before there has been an undue loss of contaminant through the boundary.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 134 , September 1983 , pp. 161 - 177
Copyright
© 1983 Cambridge University Press

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