| Abstrakt: |
Water flow in a plane bed stream (PBS) is different from the conventional open channels because of a higher ratio of "width to depth, (b/h)". Although much research has been carried out on the hydraulics of flow in PBSs, but the flow characteristics have not been fully understood yet. Thus, understanding flow resistance is necessary for flood prediction and flood routing. In the present research work, a comprehensive examination of hydraulics characteristics of PBSs is conducted by using both physical and Flow-3D numerical models of a wide rectangular channel with various sizes of bed materials. A stage-discharge relationship was developed for a PBS using four different types of bed materials. Results of the physical model indicated that for the discharges higher than 0.035 m3/s, by increasing the bed roughness, the Manning's roughness, n, increased within 3%. Results of the numerical model showed that by increasing the Froude number, Fr, Manning's roughness, n, decreased linearly. Finally, a novel general linear equation for calculating Manning's roughness coefficient, n, including all related parameters, was also obtained that can be used by the hydraulic engineers and institutional river managers. [ABSTRACT FROM AUTHOR] |
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