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Title: Improved description of selective withdrawal through point sinks
Authors: Hydraulics Laboratory (U.S.)
Environmental and Water Quality Operational Studies (U.S.)
Smith, Dennis R. (Dennis Ray), 1943-
Wilhelms, Steven C.
Holland, Jeffery P.
Dortch, Mark S.
Davis, Jack E.. Engineer
Keywords: Boundary interference
Linear stratification
Point sinks
Selective withdrawal
Stratified flow
Two-layer stratification
Withdrawal angle
Reservoir drawdown
Water quality
Publisher: Environmental Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Description: Technical Report
Abstract: Many significant studies over the past 35 years have combined to produce the present level of understanding of withdrawal processes. Analytical and empirical relationships have been developed and examined for many different density, flow, and geometric configurations. Analytical work has focused on withdrawal from two-layer or linearly stratified reservoirs. In particular, sidewall and bottom point-sink withdrawal are two geometries that have been extensively investigated. The descriptions developed by most investigators were expressions that reduced to the densimetric Froude number. It is troublesome, however, that the critical Froude numbers in these mathematical descriptions at similar flow conditions vary so greatly. In an effort to reduce the variance in these expressions, the authors use the concepts of "withdrawal angle" and symmetry to incorporate the effects of lateral geometry or topography into the critical Froude number description. The authors' development of this relationship greatly simplifies the array of coefficients that is reported in the literature for various outlet configurations and patterns of density stratification. The relationship was developed through analytical evaluation of existing expressions and subsequent laboratory experimental verification. Observed prototype conditions, comparing favorably with predictions made with this technique, further verified its credibility. The authors explicitly included in the development of this more generalized description of withdrawal the effects of arbitrary boundary interference. For linear stratification, the developed relationship is descriptive of intermediate withdrawal and withdrawal with arbitrary interference and reduces to the analytical description of bottom or surface withdrawal. Results of experiments verified the applicability of this relationship for all three potential withdrawal conditions (i.e., intermediate, surface or bottom, and arbitrary interference).
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Technical Report

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