# Projects & Programs

## Simulation of Flow Under Tainter Gates

Computational fluid dynamics (CFD) models of the spillways at the John Day and the Dalles Dams were constructed to better understand the velocity field near the tainter gate. These models use the Flow-3D^{®} commercial program to solve the Reynolds-averaged Navier-Stokes equation to simulate transient free-surface flows. To reduce the computational effort required to operate the CFD model, the model domains were reduced to a single Two-Dimensional(2-D)plane that passes through the center line of the bay. This approximation is appropriate for understanding hydraulic phenomenon in proximity to the tainter gate centerline; however, differences between the CFD model and prototype would be expected near the piers on either side the tainter gate. Several Three-Dimensional(3-D)phenomenon occur near these piers including sometimes large vortices, which will not be captured by this 2-D model. In addition, far upstream of the gate the lateral flow component has been shown to be significant depending on powerhouse and spillway conditions. Therefore, if results far upstream of the gate are required, a 3-D model of the forebay that incorporates these lateral flows should be used.