Comprehensive Flow Analysis of Dokan Dam’s Morning Glory Spillway: Utilizing Advanced Numerical and Physical Models

Spillway is a hydraulic structure designed to release of excess water, from the upstream to the downstream area of a dam. In the present study, a three-dimensional numerical model was employed using Flow-3D software. The accuracy of the model was verified through experimentation with a physical model scaled at 1:77. The objective was to analyze the flow characteristics of a distinctive type of morning glory spillway (MGS) in the Dokan Dam in Iraq. The study investigated various flow characteristics, including the discharge release, pressure and velocity distributions, and Froude number characteristics. The findings revealed that the relative error of flow rates was generally under 5%, indicating a good agreement between the numerical and physical models. Also, the discharge fluctuation was observed at low water levels and disappeared at higher water levels, due to continuous discharge at elevated water levels. Regarding pressure distribution, most discrepancies between the physical and numerical results were concentrated at specific points within the vertical shaft, and the highest pressure recorded at the bottom of the vertical shaft. Furthermore, the maximum and minimum recorded average velocities were 26.78 and 0.78 m/s, observed at Sects. 3 and 4 for water levels of 516 and 512 m, respectively. Finally, the analysis of Froude numbers showed that the downstream tunnel's flow regime transitioned from subcritical (Fr < 1) for lower water levels (512 and 513 m) to supercritical (Fr > 1) for higher water levels (514, 515, and 516 m) due to increased flow velocities.