Numerical simulation of Flow Field in Stilling Basin USBR VI

One of the most conventional types of energy dissipators is stilling basin USBR VI. Stilling basin USBR VI is also one of the oldest basins designed for dissipating the pipe outlet flow. This stilling basin is made of a small boxlike structure with a hanging wall and an endsill. Hanging wall is to distribute the energy of incoming flow to basin width. The mentioned basin has no need to tailwater for successful performance. In this research, the Flow3D software has been used to model the specifications of flow field qualitatively and quantitatively. On the other hand, the numerical model used in this study is according to physical model built by author in the hydraulic lab at the Tarbiat Modares University. In this model, basin and downstream channel widths are constant. Three incoming pipes with different diameters were also used to investigate the effect of W/De ratios. In order to validate the numerical model, the recorded pressures on hanging wall and flow depth on endsill in physical model as well as the velocity profile of incoming pipe were compared with the corresponding experimental results of Nikuradse in 1932 [10]. The results of flow field show that the flow rate is higher in the vicinity of side walls for the hanging walls and beginning of downstream channel. The distribution of flow rate in width is however uniform at the distance of basin length from endsill in downstream channel. Furthermore, different W/De ratios have different diffusion velocities of incoming jet. Incoming jet interaction and the backward flow will cause the higher rate of jet diffusion, the higher W/De ratios, the higher rate of jet diffusion.