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LABORATORY AND NUMERICAL INVESTIGATION OF LONGITUDINAL DISPERSION IN OPEN CHANNELS 1
Author(s) -
Seo Il
Publication year - 1990
Publication title -
jawra journal of the american water resources association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.957
H-Index - 105
eISSN - 1752-1688
pISSN - 1093-474X
DOI - 10.1111/j.1752-1688.1990.tb01415.x
Subject(s) - dispersion (optics) , mechanics , flume , open channel flow , flow (mathematics) , channel (broadcasting) , mixing (physics) , mathematics , materials science , physics , engineering , optics , electrical engineering , quantum mechanics
The non‐Fickian nature of the longitudinal dispersion in natural channels during low flow has been investigated using both laboratory experiments and the numerical solution of the proposed mathematical model which is based on a set of mass balance equations describing the dispersion and mass exchange mechanisms. Laboratory experiments, which involved collection of channel geometry, hydraulic, and dye dispersion test data, were conducted to obtain sets of experimental data on a model of four pool and riffle sequences in a 161‐ft long tilting flume in the Hydrosystems Laboratory at the University of Illinois at Urbana‐Champaign. The experimental results indicate that flow over the model pool‐riffle sequences is highly nonuniform. Concentration‐time curves are significantly skewed with long tails. The mixing and dispersion in the laboratory channel was simulated using a numerical solution of the mathematical model in which the finite difference method developed by Stone and Brian (1963) was used as a solution technique. The comparison between measured and predicted concentration‐time curves shows that there is a good level of agreement in the general shape, peak concentration, and time to peak. The proposed model shows significant improvement over the conventional Fickian model in predicting dispersion processes in natural channels under low flow conditions.