عنوان مقاله [English]
The combined behavior of the overflow flow from the overflow with the outlet jet under the valve creates different conditions downstream of such structures and causes scouring downstream of these structures. To solve this problem, the overflow and the valve can be combined. And formed a centralized hydraulic system called a weir-gate, which allowed the transfer of sediment from under the valve and floating material from the spill. The geometry of the present research model in FLOW-3D software was created in a rectangular channel with a sedimentary and erodible bed state and in a non-lateral compression state. Bed materials, non-stick sand and fluid used were considered as clear water and zero channel slope. In this study, two turbulence models (LES) and model (RNG) and 3 equations of bed load transfer rate were used and after validation with laboratory data, it was observed that the numerical model data with Van Rijn relation And with LES turbulence model with coefficient of determination R2 = 0.985 and mean absolute error RMSE = 0.107 has a good fit with laboratory data. The presented results indicate that with increasing upstream depth, the maximum scour depth increases Find. Also, by increasing the height of the overflow structure in a fixed opening of the valve, the maximum scour depth increases due to the jet falling, and with increasing the opening of the valve, the height of water on the structure decreases and also the outlet jet decreases and causes Reduce scour depth. Also, with increasing the flow rate over the overflow and under the valve and the upstream water level, the maximum scouring depth increases.