Bottom outlet dam flow: physical and numerical modelling

This paper presents an analysis of flow parameters through a bottom outlet conduit with gated operation using physical and numerical models. A physical model of the regulating bottom outlet of Shahryar dam in Iran was used to investigate the hydraulic forces on the service radial gate and flow patterns within the conduit. The model was constructed from Plexiglas, and discharge and pressure data were recorded for different gate openings. The Froude law of similarity was satisfied in the hydraulic modelling, allowing for an investigation of the dynamic similarity of inertial and gravitational forces. The numerical scheme was based on using the natural-element method to study hydraulic forces and flow parameters within the conduit and the finite-element method to evaluate the natural frequencies of the radial gate. The results of the calculations for different radial gate openings showed good agreement with those from physical modelling for the pressure distributions throughout the flow domain and on the gate.