Evaluation of the Water Surface Profile over Semi Elliptical Side Weir

A side weir is a hydraulic structure with free flow، which is installed at one side and parallel to an open channel. It allows the water to overflow when the surface of the water in the channel rises above the weir crest. This structure affects the depth and the flow rate in the channel. Awareness regarding the effect of this structure on the depth of water and flow rates can affect decision making for the proper hydraulic design of the channel and its side weir. In this research، 36 semi elliptical side weirs were tested in 298 settings، varying in an experimental main channel geometrical characteristics، and subcritical conditions. The range of discharge was varied from 10 to 70 lit/s. The water surface profiles over semi elliptical and rectangular side weirs were investigated and interpreted through velocity profiles. Additionally، the effects of increasing the discharge in the main channel، and varying the height، length and curvature of weir on the water surface profile were examined for this type of weir were studied. Moreover، the result of experimental water surface profiles were compared with the water surface profiles calculated by the Runge-Kutta method over rectangular and semi elliptical side weirs. The results indicated that the accuracy of this method was increased by raising the height and length of the weir، and the reducing the discharge.