Longitudinal mixing in meandering channels : New experimental data set and verification of a predictive technique
Boxall, J. B. and Guymer, Ian. (2007) Longitudinal mixing in meandering channels : New experimental data set and verification of a predictive technique. Water Research, Volume 41 (Number 2). pp. 341-354. ISSN 0043-1354Full text not available from this repository.
Official URL: http://dx.doi.org/10.1016/j.watres.2006.10.010
Evaluation of longitudinal mixing processes in open channel flows is important in environmental management, requiring the quantification of mixing coefficients. Estimates of these coefficients sufficiently accurate for environmental impact assessments cannot be achieved using current theoretical or semi-empirical methods for natural channels. This inaccuracy is caused by a limited understanding and quantification of the interaction of the dominant mechanisms resulting from natural channel features, such as plan form curvature and changes in cross-sectional shape. Experimental results are presented here from studies conducted in three self-formed channels, developed by known discharges. Longitudinal mixing was investigated at various flow rates within each of the channels by monitoring the development of tracer plumes during transit through the channels. Using an optimisation procedure, coefficients required for solution of the one-dimensional advection dispersion equation (1D-ADE) were found in the range 0.02-0.2 m(2)/s. The coefficients were found to vary as functions of longitudinal meander location, channel form and discharge. Predictions of these longitudinal mixing coefficients were made using a mathematical technique requiring only channel form properties and flow rate as inputs. Predicted values were typically within 20% of the measured values, although deviation of up to 50% was found for the lowest discharge in each channel. This large error is likely to have been caused by increased dead zone effects associated with channel bathymetry at low discharges that are not captured by the method. The method was shown to be capable of capturing the variation in the longitudinal mixing coefficient with longitudinal meander location, with channel form and with discharge.
|Item Type:||Journal Article|
|Subjects:||T Technology > TD Environmental technology. Sanitary engineering
G Geography. Anthropology. Recreation > GE Environmental Sciences
T Technology > TC Hydraulic engineering. Ocean engineering
|Divisions:||Faculty of Science > Engineering|
|Journal or Publication Title:||Water Research|
|Publisher:||Elsevier Science Ltd.|
|Official Date:||January 2007|
|Number of Pages:||14|
|Page Range:||pp. 341-354|
|Access rights to Published version:||Restricted or Subscription Access|
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