EXPERIMENTAL AND NUMERICAL STUDY OF THE LOCAL SCOUR CAUSED BY SEDIMENT RELEASING THROUGH A DAM GATE

Abstract

 This study experimentally and numerically investigates the relationship between flow structure and the scour process around a slit weir. First, we carry out a movable bed experiment on the scour. In this experiment, a weir with a rectangular slit is used to simulate physically the scour induced by sediment releasing through a dam gate. The stereo PIV method is applied to measure spatially and temporally flow velocity fields on a movable bed. Next, we carry out three-dimensional numerical analyses using the bed topography measured in the scour experiment. The numerical analysis solves the Reynolds-averaged Navier-Stokes (RANS) equations coupled with the VOF method and the k-ω SST turbulence closure model. The analytical results agree well with the measurements. Both results show a tornado-like vortex near the slit. This vortex is found to contribute highly to the temporal evolution of the scour hole.