Estimating Hydrodynamic Characteristics of Sediment Exclusion Labyrinth Weir Using 3D Numerical Analysis

Labyrinth weir was improved structures of existing linear Dam. The improved structures made by arranging triangle, rectangle or trapezoid, etc. repeatedly to increase the overflow discharge. Labyrinth weir remarkable not only increase overflow discharge but also energy dissipation and aeration effect. However, weakness of sediment deposition still existed in upstream of weir. If the severance of sediment transport occurred, it was possible to cause the ecological disturbance by affecting the ecosystem in downstream of weir. In this study, Slope type and Reverse-wedge hole type were changed from ordinary trapezoid labyrinth weir(Normal type). Using velocity distributions and turbulence characteristics due to changed shapes, the cause of the increase of sediment exclusion efficiency was examined. The upstream boundary condition(BC) was set to steady water surface elevation and the downstream BC was set to outflow. After steady flow, generating sediment particle at upstream BC and the sediment exclusion efficiency was estimated by counting remained sediment particles in upstream of weir. As a result, sediment exclusion efficiency increased 10.1 times for Slope type and 5.6 times for Reverse-wedge hole type compared with Normal type. And the hydrodynamic characteristics inside weir was analyzed. The increase of bottom velocity made sediment exclusion efficiency increase for Slope type and the increase of swirling strength near walls help sediment to exclude for Reverse-wedge hole type. In the case of the sediment exclusion labyrinth weir, the sediment continuity can be to enhance by changing shape simply. And it will be expected that it have the greater availability because there is an positive role in improving ecosystem health.