Numerical Modeling of Probable Maximum Flood Flowing through a System of Spillways

Abstract

The results of a numerical model study of probable maximum flood (PMF) flow through a system of spillways consisting of an existing service spillway and a new auxiliary spillway are presented. A commercial computational fluid dynamics (CFD) code, Fluent, was used to solve the time-dependent Reynolds-averaged Navier-Stokes equations, a standard turbulence k-ε model with wall functions, and a water volume of fluid fraction equation. A two-dimensional approach velocity profile was used at the upstream inlet cross section. Water levels, flow splits between the existing and auxiliary spillways, and flow patterns were predicted and compared. A tentative design was chosen, constructed, and tested in a 1:54 scale physical model. Testing results were used to validate the CFD model. Results demonstrate that the CFD model is validated as accurate in the prediction of water levels in the reservoir, the integrated approach used is cost-effective and efficient in optimizing the designs of the auxiliary spillway, the tentative design cannot pass the PMF at the maximum pool level which suggests further modifications being necessary in the physical model.