Numerical simulation of the effect of submerged vanes on strength of secondary flow at 180° bend with lateral intake

Submerged vanes are plane structures placed on river bed with an angle to the approach flow which cause secondary flow. They can be used to reduce sediment entrainment to water intake structures. Studying the effect of submerged vanes on the strength of secondary flow and possible sediment diversion near the bed are the goals of this paper. The simulation includes two cases, one in which submerged vanes are placed in front of the intake and the other for no vanes. Therefore, three-dimensional Reynolds-Averaged Navier-Stokes equations for turbulent flow in front of intake in 180° bend was solved numerically. The CFD solver FLUENT was used to solve equations and the results of numerical models were compared with available experimental data. Investigations showed that the secondary flow around vanes was at the same direction of main secondary flow. Therefore by intensifying, it causes more deviation of near bed streamlines toward the inner bank and surface streamlines toward the outer bank. Furthermore, it causes more water diversion with less amount of sediment. The separation zone at main channel is widening near the surface of inner bank and the vanes prevent the formation of the saddle stagnation zone and reverse flow toward the intake in main channel, so that less sediment enter into the intake.