Abstract Submission: An aquatic organism bypass structure was to be designed to allow for the passage of fish and other organisms around a low-capacity reservoir and dam. The structure was designed so that flow from the river bifurcates to two sets of fish screens, the north screen, and the south screen, which would allow fish to pass via two bypass flumes. The majority of flow passes through the screens to continue downstream through two dewatering channels. Flow in the dewatering channels is controlled by 8 sluice gates and flow measurements are made just upstream of the gates. The accuracy of those flow measurements is a critical design criterion and affects how the gates and upstream fish screens are operated. Sonar-style flow measurements typically require uniformly distributed flow, with only minor deviation from the cross-sectional average velocity for the highest degree of accuracy. To ensure uniform velocity distribution through the sluice gates, hydraulic simulations were analyzed using ANSYS CFX, a commercial software package for computational fluid dynamics (CFD). It was found that flow distribution in the dewatering channels was greatly affected by drag induced as flow passed underneath the fish bypass flumes. Multiple design iterations were analyzed. It was found that a uniform velocity distribution was obtained by moving the gates downstream an allowable 170 ft, isolating the flow to each gate via divider walls, and including a 2:1 chamfered ceiling upstream of each gate. CFD was very useful in developing alternatives that would meet several design constraints within a limited footprint.
