Hostname: page-component-cd9895bd7-jkksz Total loading time: 0 Render date: 2024-12-26T08:43:32.901Z Has data issue: false hasContentIssue false
  • English
  • Français

Optimal discharge profiles for sudden contaminant releases in steady, uniform open-channel flow

Published online by Cambridge University Press:  20 April 2006

N. C. Daish
N. C. Daish
Affiliation:
Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Silver Street, Cambridge CB3 9EW
Get access Rights & Permissions [Opens in a new window]

Abstract

The effect of varying the initial concentration distribution is investigated for a sudden contaminant release in a uniform straight channel. Taking the optimal choice to be that which maximizes the variance of the contaminant cloud far downstream, it is found that, unless the topography is very unusual, the largest variance can be generated by splitting the contaminant into two parts, placing the larger part at the bank where the channel bed slopes most gently, and the remainder near to where the channel is deepest. This procedure significantly reduces peak concentrations far downstream when compared with making the entire release at any single point across the flow. Even at distances as large as six times the e-folding distance for cross-sectional mixing, the splitting of the discharge is shown to reduce the peak concentrations by a third.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 159 , October 1985 , pp. 303 - 321
Copyright
© 1985 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Aris, R. 1956 On the dispersion of a solute in a fluid flowing through a tube. Proc. R. Soc. Lond. A 235, 67–77.Google Scholar
Chatwin, P. C. 1972 The cumulants of the distribution of concentration of a solute dispersing in solvent flowing through a tube. J. Fluid Mech. 51, 63–67.Google Scholar
Daish, N. C. 1985 Shear dispersion in open channel flows. Ph.D. Thesis, University of Cambridge.
Fischer, H. B., List, E. J., Koh, R. C. Y., Imberger, J. & Brooks, N. H. 1979 Mixing in Inland and Coastal Waters. Academic.
Smith, R. 1979 Calculation of shear dispersion coefficients. In Mathematical Modelling of Turbulent Diffusion in the Environment (ed. C. J. Harris), pp. 343–362. Academic.
Smith, R. 1981 The importance of discharge siting upon contaminant dispersion in narrow rivers and estuaries. J. Fluid Mech. 108, 43–53.Google Scholar
Smith, R. 1982a Where to put a steady discharge in a river. J. Fluid Mech. 115, 1–11.Google Scholar
Smith, R. 1982b Gaussian approximation for contaminant dispersion. Q. J. Mech. Appl. Maths 35, 345–366.Google Scholar
Smith, R. 1984 Temporal moments at large distances downstream of contaminant releases in rivers. J. Fluid Mech. 140, 153–174.Google Scholar
Taylor, G. I. 1953 Dispersion of soluble matter in solvent flowing slowly through a tube. Proc. R. Soc. Lond. A 219, 186–203.Google Scholar
Taylor, G. I. 1954a The dispersion of matter in turbulent flow through a pipe. Proc. R. Soc. Lond. A 223, 446–468.Google Scholar
Taylor, G. I. 1954b Conditions under which dispersion of a solute in a stream of solvent can be used to measure molecular diffusion. Proc. R. Soc. Lond. A 225, 473–477.Google Scholar