Investigation of the effect of semicircular corrugated side weir height on discharge coefficient and water surface profile in the main channel

Side weirs are important and practical hydraulic structures in water conveyance systems that are installed on the side wall of the channel to divert excess water from main channels. In this research, the effect of the height of two-side semicircular labyrinth side weir on the discharge coefficient and water surface profile in 3D by using the FLUENT software. side weirs were used in three, four and five cycles with a height of 10,15 and 20 cm and an opening length of 40 cm. The discharge coefficient and water surface profile obtained from this simulation were compared with experimental results for validation. The computed values have a good agreement with the experimental data and the error percentage for the discharge coefficient is between zero and 7% and the relative error was decreased by decreasing of Froude number. Based on the results, as the height of the side weir increases, the rate of water surface fluctuations in the main channel and along the side weir decreases. On average, with every 5 cm reduction in the height of the side weir, the rate of water surface decreases by 3%. Also, the discharge coefficient of the side weir decreases with decreasing congress radius and with increasing the side weir height and upstream Froude number. Therefore, the semicircular labyrinth side weir of three-cycle with height P = 10cm has a higher discharge coefficient than the other side weirs under study.