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Thomas Library

Honors Thesis Archive

Author Joseph M. Fugate
Title Calibration and assessment of Wittenberg University's recirculating laboratory flume in generating various bed states of mobile sand beds
Department Geology
Advisor Michael Zaleha
Year 2012
Honors Departmental Honors
Full Text View Thesis (0 KB)
Abstract The purpose of this study was to evaluate quantitative relationships between fluid flow and bed form generation in Wittenberg University's recirculating laboratory flume. The study also established the criteria for conditions under which various bed states are generated (including lower stage plane beds, ripples, dunes, and upper stage plane beds) and protocols for measuring important flow parameters, such as flow depth, velocity, and water surface slope. Laboratory flumes are invaluable tools that allow students to learn fundamental processes of sediment transport that can then be applied to interpreting and predicting bed forms and sedimentary structures that are present within the rock record. This information has important implications in engineering applications, as well as sedimentary geology. Sixteen flume runs were conducted using two batches of sediment with mean grain diameters of 0.27 mm and 0.57 mm. Results were compared with previously published bed phase diagrams which plot flow velocity against grain size, flow depth against velocity, bed shear stress against grain size, and dimensionless bed shear stress against grain size. Results show that lower stage plane beds and ripples are generated under conditions similar to those of previous studies. Ripples formed in flow depths of 0.09 m to 0.1 m, with flow velocities of 0.33 m/s to 0.56 m/s and with slopes of 0.0007 to 0.0039. Dunes were produced in the flume, but were difficult to sustain. Upper stage plane beds were generated using both sediment sizes in flow depths of 0.045 m to 0.071 m, with flow velocities of 0.75 m/s to 1.13 m/s and slopes of 0.0084 to 0.0306. In general, Wittenberg's flume performs well in generating lower stage plane beds, ripples, and upper stage plane beds under conditions established by previous studies. Dunes are difficult to generate and sustain under the conditions established in this study. One possible solution would be to use a sediment mixture with a mean grain size closer to 0.40 mm. However, the flume may be too short to establish uniform flow along a length great enough to produce sustainable dunes, which have relatively long wavelengths.

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