Abstract
In this study, a numeral model of a stepped spillway with different steps and slopes is used. A number of hydraulic specifications considered in designing the stepped spillways are the pressure, velocity distribution, and energy dissipation. Results show that increasing of discharge and the spillway slope reduces the amount of energy loss. For a spillway with five steps and a discharge of 0.063 m3/s, the energy loss at a slope of 26.6 degrees is 85%, compared to an 82% energy decrease for a 45-degree slope. With the increase in discharge, the flow depth increases, which reduces the effect of the roughness of the steps on the upper layers of the flow. Increasing the height of the steps increases the energy loss and also increases the occurrence of negative pressures in the stepped spillway. In this case, the interaction surface between the main flow and the eddy currents increases. With an increase in the height of the steps, the sizes of the rotating vortices also increase. The presence of these large rotating vortices separates the flow from the bottom of the steps and reduces the pressure on the surfaces.