Computational Modeling of the Hydraulic Jump in the Stilling Basin with Convergence Walls Using CFD Codes

Abstract

The stilling basin has been accepted to be the most powerful hydraulic structure for the dissipation of the flow energy. The size and geometry of the stilling basin affect the formation of flow patterns, which can be influ- ential for hydraulic performance of the whole system. The NazlooDaminIranwasselectedasthestudyarea.TheUSBR II stilling basin was conducted for four convergence angles (5 ◦ ,7.5 ◦ ,10 ◦ , and 12.5 ◦ ). The convergence walls cause the jump to stabilizeinside thebasin and cause the energy loss to increase in the stilling basin. To simulate the hydraulic jump in the convergence stilling basin conditions in this region, a free surface computational fluid dynamics (CFD) numerical model has been applied. The commercially known software, FLOW-3D, was applied to numerically solve the Navier- Stokes equations for solution domains, namely the shout, the stillingbasin and thedownstream of dam, and to estimatethe turbulence flow, the standard k-e and RNG models was used. These models are based on the volume-of-fluid method, and they are capable of simulating the hydraulic jump. The cal- culated results such as the pressure, the velocities, the flow rate, the surface height air entranced, the kinetics energy, the kinetics energy dissipated, and the Froude number were compared with the scale model data where available. This allowed a comparison for the use of CFD as a cost-effective alternative to physical models. The physical model and CFD model results showed good correlations.