Investigation of effect of intermediate sill on local scouring at the end of stilling basin

In this study, a three-dimensional numerical model of sediment was simulated based on previous experimental work. The simulation was performed by using Flow-3D software the Renormalized Group (RNG) k-ε turbulence model was chosen in the numerical modeling. The scour process was calculated at the end of the USBR type VI stilling basin with impact wall, end sill and intermediate sill. To investigate the effect of intermediate sill geometry on the local scour depth, four different intermediate sill geometry were used and maximum scour depth for each model was simulated at the end of stilling basin to select the best type of intermediate sill that reduces the scouring to a minimum value. To assess the precision of the CFD program the numerical results will be compared with experimental. After the simulation, the results showed that the numerical results close to the experimental, but only had the high difference in model-5. Results showed that intermediate sill has a great effect on the scour depth at the end of the stilling basin, it has a clear difference between the results of scour depth for stilling basin with and without intermediate sill and their effects depend on it is geometry, the results showed that the minimum scour depth occurred in the square intermediate sill.