Numerical Study on Passing Flow Through Circular Channels with Side

Side weir is used as a slot in the side of main channel to direct excess flows that are above the weir crest. Such structures are used in control of flow level in irrigation, drainage networks and urban sewage disposal systems. Among these structures, circular channels are extremely important. Considerable length of sewage disposal and transmission pipeline system is made of circular channels. In this study, changes of water surface level, turbulence and flow field passing through a circular channel with side weir is simulated using commercial software. In this numerical simulation for modeling changes of flow free surface, VOF model and for simulating of the flow field turbulence, RNG k-ε turbulence model are used. In this study in order to validate the accuracy of the numerical model, the flow depth changes along the side weir, the discharge coefficient of the side weir, the passing flow over the weir, the Froude number at the upstream of the weir and the specific energy at the beginning of the weir are compared with the laboratory results. Comparison of all mentioned parameters with the experimental results show high accuracy of CFD model in predicting turbulence and flow field of passing through a circular channel with side weir. The main purpose of this simulation is gaining an understanding of behavior of passing flow through circular channels with side weir in order to use in design problems of this type of hydraulic structures.