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Stripped Bed Roughness Effect on Flow Measurement in Trapezoidal Channels with Free Overfalls

1st International Conference on Engineering and Innovative Technology, SU-ICEIT
The aim of the present investigation is to study the effects of side slope, bed slope and bed roughness on the flow over free overfalls in trapezoidal channels. Three models of trapezoidal free overfall channels have been built and tested in a laboratory flume; each model had four different bed slopes. For each slope, the bed was roughened using artificial strip roughness elements with eight different roughness patterns. The experimental testing program included ninety-six series of experiments for different ranges of Froude number. Experimental results of all models showed that the variation of (π‘Έπ’ŽπŸ.πŸ“/βˆšπ’ˆπ’ƒπŸ“) with (π’Žπ’šπ’ƒ/𝒃) for different bed slopes and various roughness patterns is simple power equation. It was also observed that values of (π‘Έπ’ŽπŸ.πŸ“/βˆšπ’ˆπ’ƒπŸ“) increase with the increase of (π’Žπ’šπ’ƒ/𝒃)values. The correlation between (π’Žπ’šπ’ƒ/𝒃) with (π’Žπ’šπ’„/𝒃) was found to be linear for different bed slopes and roughness patterns. The ratio (π’šπ’ƒ/π’šπ’„) decreases with the increase of bed slope (S). An empirical expression was obtained for the variation of (π‘Έπ’ŽπŸ.πŸ“/βˆšπ’ˆπ’ƒπŸ“) with (π’Žπ’šπ’ƒ/𝒃) and (S/n) for the free overfalls with rough beds