Simulation of free surface flow over spillway

A numerical approach is proposed to simulate and study the effect of geomet ry on the free surface flow over a tunnel spillway. A three-step solution p rocedure is proposed to speed up the solution. The first step is to obtain an approximate free surface profile and mean velocity distribution, assumin g 1D steady flow. Next, the 3D turbulent flow field is computed while the w ater 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 v olume method. A boundary fitted grid system is used to accurately resolve t he flow near the free surface with steep waves. A mixed Lagrangian-Eulerian approach is proposed to calculate the new free surface position. The numer ical results of a time-averaged free surface profile as well as pressure an d velocity distribution have been compared with some experimental data.