Experimental Investigation for Free Overfall of Flow in Semi-circular Channels

Abstract In the present paper, effects of diameter, bed slopes, and roughness on free overfall flow semi-circular channels were investigated experimentally. For this purpose, three models with built installed in a 6m long laboratory flume. These 250 cm had varying diameters 160, 200, mm. Four different slopes (S) used each these (0, 0.004, 0.008, 0.012). slope, sand particle sizes to roughen (1.18mm, 2.36mm, 4.75mm). model, experimental testing program contained sixteen series experiments. They divided into two categories: four smooth beds twelve rough beds. Different rates discharge (Q) examined total 192 tests. According results all models, Froude number ( F r ) decreases as end depth ratio y b / c increases for various roughnesses. bottom roughness, simple linear formula was developed relate brink critical ). conditions, empirical equations over found. The demonstrate good level agreement.