Performance Evaluation of Subsidiary Weir for Energy Dissipation in the Stilling Basin Using CFD Modelling

This study was aimed at assessing the utility of the subsidiary weir in the post-rehabilitation scenario of Taunsa Barrage Pakistan wherein a 7 ft. high subsidiary weir was constructed at a distance of 920 ft. downstream of the main weir. In addition to the construction of the Subsidiary weir, auxiliary devices were also provided in the stilling basin downstream of the main weir. These devices include chute blocks and dented end sill. CFD (Computation Fluid Dynamics) based software Flow-3D was employed in the current study to numerically model the Taunsa Barrage, Pakistan and simulate the flow scenario. Based on the simulations of these flow scenarios, flow parameters were recorded for each scenario and comparative analysis was carried out to assess the effectiveness of the subsidiary weir. The study concluded that the addition of a subsidiary weir affected the flow parameters (Flow depth, depth-averaged velocity, and Froude number) and the location of the hydraulic jump. Furthermore, the study concluded that the addition of a subsidiary weir resulted in lesser energy dissipation as compared to the energy dissipation observed in the absence of a subsidiary weir.