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Diffusion in a variable density liquid under conditions of turbulent, steady flow

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Title Diffusion in a variable density liquid under conditions of turbulent, steady flow
Names Harris, Dennis Roy (creator)
Behlke, Charles (advisor)
Date Issued 1964-04-30 (iso8601)
Note Graduation date: 1964
Abstract The diffusion process in a variable density, turbulent
flow is a factor which greatly influences the waste
disposal characteristics of tidal estuaries. Waste disposal
from cities and industries, is posing an increasing
threat to the estuarine environment. Accurate prediction
of the effects of proposed waste outfalls in well-mixed
estuaries (which predominate during the most critical waste
disposal season) is very desirable. The most used analytical
tool for the prediction of waste concentrations in
well-mixed estuaries, is the one-dimensional conservation
of mass equation. A lack of knowledge concerning the diffusion
process and a resulting inability to predict the
coefficient of turbulent diffusion, is a major limitation
to the use of this tool. Closed form solutions to the
equation of mass conservation are not sufficiently accurate for most real estuaries because of the required simplifying assumptions. Field determination of the average
diffusion coefficients has allowed numerical solutions
for average steady-state concentrations.
For the purpose of providing a tool for predicting
the cyclical variation of waste concentrations and improving
our understanding of the diffusion process, a dimensional
analysis for the instantaneous diffusion coefficient
(considering only bottom shear and longitudinal density
gradients) was made. Experimental work was designed to determine
the relationships between dimensionless parameters
obtained by the systematic method of Buckingham. The narrow
range of flows and depths for which consistent results
could be obtained did not allow a complete determination
of the relationships. However, the nature of the relationships obtained, indicated that they could serve as the correspondence between model and prototype for determining the longitudinal density gradient effects on the diffusion coefficient in well-mixed estuaries. Further studies are required to verify these relationships over a wider range of flows and depths.
Genre Thesis/Dissertation
Topic Sewage disposal
Identifier http://hdl.handle.net/1957/48588

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