Design of the optimum ogee spillway toe for a maximum energy dissipation

Hydraulic design of a spillway has been one of the most studied subjects in hydraulic engineering. Properly designed, flow condition dependent spillways will be able to release water efficiently and safely from a dam reservoir to the downstream. This study aims to investigate the energy dissipation at the toe of ogee spillway by making an ogee spillway with different end sill models at the downstream by using a commercially available Flow-3D. The case A model was an ogee spillway with rectangular end sill, the case B, C, D and E with a curved end sill with radius of 0.10, 0.15, 0.18 and 0.20 meters, respectively, and the case F which has an inclined end sill. The major amount of energy dissipation occurs at the toe in the region where the hydraulic jump takes place. The hydraulic jump is used to dissipate energy at the downstream. These models were compared to one another to see the corresponding energy loss respectively. To simulate the turbulent flow, the "𝑘−𝜀" turbulence model is done in the numerical modelling. The numerical result shows that the model with curved end sill dissipates more energy than others. In the case F model with inclined end sill, it can be concluded that the hydraulic jump did not occur, the velocity remained high for all cases of discharge and the energy loss is insignificant regarding its form. Therefore, energy loss changes in relation to discharge, most loss occurs at low discharge while in the case of high discharges energy loss decreases. Results indicated numerical methods as convenient and time-saving, with least errors.