Cross-Section Influence on Velocity Distribution & Energy Dissipation of a Moderately Sloped Spillway Chute Flow

Abstract

Erosion at the dam toe due to potential to kinetic energy conversion of the outlet release is a complex yet fascinating engineering challenge. The energy dissipation due to flow separation at sharp cornered geometries affects the flow stream and causes the lower velocity at the dam’s toe. To date, many of the conventional dam engineering techniques consider the dam toe as the examination point. In this research, by the use of OpenFOAM numerical model, the water flow in the spillway chute is modeled. The velocity profile of the chute flow in three different crosssections is considered for the same outlet boundary conditions. The effect of geometry on kinetic energy (velocity) reduction has been studied in order to find a trend for this type of energy cascade. Simulation results show that lateral eddies form due to generation of translatory waves and aeration processes in trapezoidal and curved edge rectangular cross sections. While these type of cross sections might be of use from the energy dissipation perspective, the higher velocities may deliver higher stagnation or uplift pressures in cases of vertical offset on the spillway’s slab (bed).