Numerical Simulation of Turbulent Free Surface Flow in Channel with Side -Weir

Side weirs are flow diversion devices which are widely used in irrigation and drainage systems as a head regulator of distributaries, land drainage and urban sewage systems. In this research, flow pattern and free surface of water in a channel with a sharp crested side -weir is simulated by using FLUENT software. The volume of fluid (VOF) scheme and RSM turbulence model are used for numerical simulation of the turbulent free surface flow. Comparison between numerical results and laboratory measurements of water surface profile and channel discharge show that the model can predict the flow pattern over side weir with reasonable accuracy. By comparing flow patterns over a side-weir within the maximum and minimum discharge ratio it was revealed that, distance of the dividing stream surface from left wall varies in depth. Also size and location of 3D vortex flow is dependent on discharge ratio of side-weir.