Mathematical and experimental modeling the study of flow pattern at an abnormal stilling basin

In the present study, the optimum design of an abnormal stilling basin which may not to be categorized in the available standards, is investigated downstream of bottom outlet of a dam, using a physical model and three-dimension (3D) numerical simulation. The length of basin, shape and location of blocks and sills are changed and behavior of flow in stilling basin is investigated. RNG (Renormalization Group) is used for turbulence modeling scheme along with the Volume Of Fluid (VOF) for distinguishing the free water surface and Fraction Area/Volume Obstacle Representation (FAVOR) for detecting geometry components of the basin. According to the performed verification with the experimental data, it is concluded that the total deviation between numerical results and experimental data for velocity is below 15%. Results showed that increasing the length of basin is the most reason of decreasing flow velocity at the tail water where by increasing about 133% of the basin length, the velocity decreased about 34% at the tail water. Moreover, stepped sill at the end of basin had considerable effect on controlling hydraulic jump. Finally, it is concluded that the optimum design dissipated about 65% of the energy more in comparison with the initial design.