The Hydraulic Assessment of Side Weir using 3D Computational Fluid Dynamics Program

Abstract The objectives of this study are to analyze flow characteristics for a side weir, which is aninlet structure for flow discharge reduction in the main channel through 3 dimensionalnumerical analysis and to understand the efficiency of the overflow effect at the side weir. Inthis study over 40 simulations using FLOW-3D, a computational fluid dynamics program wereconducted, and the results were analyzed to find the influence of the flow hydraulics, geometry,channel and weir shapes on the coefficient. It is especially considered the relatively high stage indownstream that may cause flow within channel to be backed up along the channel.Additionally by setting up the scale of simulations much larger than the existing test equipmentdesigned by other researchers, it is intended to analyze more accurate hydraulic behavior alongwith the realistic hydraulic features such as structures and volumes of flow. The results showthat for design with subcritical flow only if the Froude number of upstream is sustained below0.5 and the length of weir is 33-100% of the width of channel, it is expected to improve theefficiency of the overflow over a side weir.Keywords : overflow effect, side weir, FLOW-3D