Flow turbulence conditions and sensitivity of bucket-type spillway geometry parameters in energy dissipation

Energy dissipation downstream of dams is considered one of the important issues in these structures. Various structures have been employed to perform this function. Among them, bucket-type spillways are of great importance, where the outflow jet from these structures faces complex issues, including jet diffusion and downstream erosion. With the hardware and software advancement of numerical simulation systems, the evaluation of this phenomenon is possible at a lower cost compared to laboratory conditions. In this research, using FLOW-3D software and the RNG turbulence model, the effects of various geometric and hydraulic parameters related to the bucket-type spillway on the outflow jet have been investigated. The results of the RNG turbulence model show better agreement with laboratory results compared to the (k-ε) turbulence model. The relative error in energy reduction between laboratory results and numerical model results is less than 5%, and the error related to maximum jump length is less than 7%. The changes in spillway geometry include changes in the spillway angle from 52° to 32° and changes in the spillway arc radius from 12-19 cm.