A Comparison of using Turbulence Models in Simulating Hydraulic Jump in Diverging Rectangular Sections with Fluent Software

Stilling basins are one of the most common structures for energy dissipation of flow with high velocity and among different sections and types of these basins، diverging basins have better performance and lower constructional costs. In this research، the feasibility of 3D numerical simulation of diverging hydraulic jump in rectangular basins was investigated using standard and RNG turbulence models using Fluent software. The free surface was determined using the VOF method. The outputs of numerical model in comparison with the results of physical model of hydraulic jump in diverging rectangular basins with diverging angels of and showed that the standard turbulence model evaluated the free surface of water، jump length and maximum velocity in defined sections better than RNG turbulence model. this model show that the efficiency of diverging basins in decreasing length of jump is more better than the classic basins. So this model is recommended for simulating hydraulic jump in diverging sections. Results showed that the mean relative error of water surface obtained from numerical model and measured values is about 7 percent. Modeled Velocity profiles were in good agreement with measured data. Also the numerical model showed the vortices that were accrued because of diverging walls as well as experiment investigations. These vortices accrued near the right side of diverging wall in high Froude numbers and in lower values of Froude numbers، accrued in both two sides of walls. The intensity of vortices was increased by increasing the angle of diverging walls.