Simulation of Free Surface Flow over Spillway

Abstract

A numerical approach is proposed to simulate and study the effect of geometry on the free surface flow over a tunnel spillway. A three-step solution procedure is proposed to speed up the solution. The first step is to obtain an approximate free surface profile and mean velocity distribution, assuming 1D steady flow. Next, the 3D turbulent flow field is computed while the water surface profile is kept fixed. Finally, the water surface is set free to move and generate waves. The governing equations for weakly compressible flow (compressible hydrodynamic flow) are solved with an explicit finite volume method. A boundary fitted grid system is used to accurately resolve the flow near the free surface with steep waves. A mixed Lagrangian-Eulerian approach is proposed to calculate the new free surface position. The numerical results of a time-averaged free surface profile as well as pressure and velocity distribution have been compared with some experimental data.