Classification and Prediction of Buoyant Surface Discharges

by Gilbert R. Jones, Environ Corp, Arlington, United States,
Gerhard H. Jirka, Environ Corp, Arlington, United States,

Document Type: Proceeding Paper

Part of: Hydraulic Engineering


Past efforts to predict the dilution and geometric characteristics of buoyant surface flows have relied on integral modelling techniques involving the solution of a series of differential equations. Although these models have proven successful in predicting simple surface flows, they are extremely limited in applicability due to their inability to account for boundary interaction, strong buoyancy, and recirculation. The proposed method is a two step process involving: 1) classification of the flow depending on the most significant discharge and ambient characteristics, and 2) quantitative prediction of flow through use of simple analytical expressions applied to limited regions within the flow. Classification of the flow is used to distinguish between the great variety of flow patterns that exist under widely differing ambient and discharge conditions. Mathematical prediction of dilution and geometric parameters of the flow (width, depth and centerline trajectory) requires the use of length scales to delineate subregions within the flow. Analytical expressions based on perturbation solutions of the governing equations are applied to each subregion. Although the proposed methodology could be done in any of several frameworks, the authors have chosen that of a computer expert system which provides a practical engineering tool for both design and regulatory use.

Subject Headings: Fluid flow | Overland flow | Fluid mechanics | Buoyancy | Water discharge | Dilution | Water pollution

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