Page - 139 - in Book of Full Papers - Symposium Hydro Engineering

with results computed with FLOW3D, a commercially available 3-D CFD software application. 6.1.5. Analysis with Scale Physical Model To provide hydraulic engineering information not otherwise available, a 1:50 scale physical model of the FCO Spillway chute, based on Froude number similarity, was built at Utah State University immediately following the spillway chute failure. The model includes the Flood Control Outlet structure, the concrete chute along with energy dissipaters, and part of the Feather River immediately downstream of the terminal end of the chute. This model was used to determine a rating curve of the FCO Spillway structure, to verify flow depth and velocity obtained from numerical models, and to understand flow patterns in the chute in case the spillway construction was not completed in a single construction season. Initial studies with the physical model were limited to three alternative designs proposed for recovery: a plunge pool alternative, an interim chute, and full restoration of the original concrete chute. Fig. 6 shows the 1:50 scale model of the plunge pool alternative of the FCO Spillway chute; this alternative modified the scour hole created by the spillway failure for use for conveyance and as an energy dissipating device. This alternative was found to be feasible based upon the CFD model runs, but the physical model results showed standing waves on the plunge pool as high as 46 m (150 ft) during a release peak design flow of 8382 m3/s (296,000 ft3/s). Therefore, this alternative was discarded. 139