The effect of thickness increment on the characteristics of water flow over semicircular weir

In this research, the hydraulic characteristics of the flow over the semi-circular weir with the semi-circular edge was investigated by laboratory experiments. For this purpose, 15 models were created. The models were tested in a laboratory flume 12 meters long, 0.80 meters wide and 0.90 meters deep. The results showed that the relationship between the discharge and the other variables is a direct relationship and for all the used models but with varying percentages. Twenty-seven additional experiments were conducted for the purpose of determining the critical thickness. It was observed that the discharge started to decrease between the two thicknesses 1.2 cm and 1.6 cm. Through the experiments, it was obtained that the value of the critical thickness is 1.21 cm. An empirical equation and simple application was developed in order to calculate the discharge (Q) over the semi-circular weir with semi-circular edge. This equation showed a very high correlation with the measured results. It was found that the best value of the discharge over the semi-circular weir with semi-circular edge was obtained when the thickness was 1.2 cm and the radius of the weir's aperture was 25 cm.