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Title: Boundary shear in rectangular and compound ducts
Author: Patel, Harish S.
ISNI:       0000 0004 2730 2463
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 1984
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Experiments have been performed in a rectangular duct for aspect ratios, B/H, varying between 0.1 and 10, and in a compound duct comprising of one rectangular main channel and two symmetrically disposed flood plains, for 0.057 < (H-h)/H < 0.491, B/b = 5.2 and b/h = 0.934, in order to obtain boundary shear stress distributions and primary flow isovels. follows page 41. The symbols are defined in Fig.(3.1) which In the smooth rectangular duct, perturbations were noticed in the bed shear stress distributions and were related to the secondary flow cells, which in turn depend upon the aspect ratio. An empirical equation is presented giving the number of these secondary flow cells for a given aspect ratio, for B/H < 3.0. Equations are also presented giving the percentage of the total shear force carried by the walls, the mean boundary shear stresses, the maximum boundary shear stress and the bed centreline shear stress, in terms of the aspect ratio. Experiments in the rectangular duct were also performed with rough and differentially roughened surfaces. The results are compared with the open channel results at comparable aspect ratios and small differences are shown to exist. In the compound duct, the boundary shear force results are used to calculate the apparent shear force on vertical, horizontal and inclined interfaces. Their variation with depth is studied to explore the lateral and vertical transfer of momentum. The effect of introducing roughness on the flood plains is also examined. The three-dimensional nature of the flow in the compound duct is demonstrated by the lateral variation of the depth mean velocities, the primary flow isovels and the variation of subsection mean velocities on the flood plains and in the main channel. Various sub division methods for discharge predictionlre examined and the methods with horizontal and inclined interfaces are shown to give the best discharge results. The results are also compared with the open channel results and are found to generally accord with them.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available