Numerical Modeling of Multi-Horizontal Submerged Jets (MHSJ) Stilling Basins using CFD Techniques

One of the most difficult issues to address when designing hydraulic structures is the energy dissipation in spillways, outlets and stilling basins. Different approaches exist to ensure that the flow properties downstream of the hydraulic structure are suitable to avoid foundation scour, streambed erosion and other undesirable processes. The present work focuses on the numerical modeling of Multi-Horizontal Submerged Jets (MHSJ) stilling basins. This particular type of structure aims at forming a submerged hydraulic jump where the staggered distribution of inlet jets interferes with the formation of coherent turbulent structures, thus affecting vortex shedding and so contributing to more favorable sequent depth ratios and overall energy dissipation.

The work presented herein aims at characterizing and understanding of the flow in MHJS stilling basins. To this end, an air-water RANS k-ε model based on the VOF method is implemented using the CFD code OpenFOAM. A three-dimensional structured mesh of rectangular elements with selective refinement is used.

The model accuracy is assessed using experimental data obtained from a physical model free from scale effects. This process shows that CFD models are capable of reproducing the flow in MHSJ stilling basins. The existent limitations when reproducing flow features such as vortex formation and hydraulic jump roller characteristics are discussed and some recommendations for future work are outlined.