Executive Summary : | Flow over spillways can cause local scour at the downstream end due to the high kinetic energy causing it. To ensure safety, a stilling basin is provided as an energy dissipator at the spillway's entrance. However, even after the hydraulic jump formation, the energy within the water remains high, causing local scour and endangering the stability of the stilling basin and the spillway. Several studies have been conducted on the flow over stilling basin, either by changing the basin length or roughness, but the results remain indecisive, especially regarding local souring. Some studies have also suggested end sill provision to reduce local scour at the basin downstream, but these results are not encouraging. A redesign of the stilling basin is necessary to maximize energy dissipation within the basin and restrict local scour at the downstream end. Experimental studies show that turbulent eddies between adjacent dunes boost bed shear stress, resulting in energy dissipation. An inward concave shaped end sill can be useful for energy dissipation, and a combination of a series of dunes and an inward concave shaped end sill can maximize dissipation rate. Geocells are found to be an effective tool for limiting sediment transport and minimizing local scour. The combination of a series of dunes, inward concave shaped end sill, and geocells will provide a stable and durable stilling basin design. A detailed study of turbulent features for different flow Froude numbers will be performed, and numerical studies will be carried out using FLOW 3D software to optimize the dune shape under which maximum energy can be dissipated. |