Hydraulic experiments and numerical simulations to understand flow characteristics and sediment transport in sediment bypass tunnels

A sediment bypass tunnel (SBT) is one of the key sediment management measures used in dams. However, abrasion damage to the tunnel invert concrete caused by high-velocity sediment transport remains a significant concern. Herein, hydraulic experiments and numerical simulations were conducted to understand flow characteristics and sediment behavior. Hydraulic experiments confirmed that the cross-sectional distribution of the amounts of transported sediments varied with the ratio of tunnel width to water depth (aspect ratio). Turbulence models were examined through numerical simulations, and the results confirmed that the Large Eddy Simulation model, which can represent the secondary flow of the second kind, was suitable for solving flows in SBTs.