NUMERICAL SIMULATION OF DAM BREAK FLOWS USING DEPTH AVERAGED HYDRODYNAMIC AND THREE DIMENSIONAL CFD MODELS
This paper investigates the capability of three different numerical models to simulate sudden dam break flows in the presence of an obstacle. The numerical results from a two dimensional (2D) hydrodynamic depth averaged model and two fully three dimensional (3D) computational fluid dynamics (CFD) models are presented. The models selected for this study are: (1) the free and opensource code TELEMAC 2D, (2) the commercially available CFD software package FLOW 3D, and (3) the free and open source CFD code OpenFOAM. TELEMAC 2D is based on the solution of the shallow water (Saint Venant) equations, which neglect vertical velocities and accelerations. Both FLOW 3D and OpenFOAM are based on the solution of the Navier Stokes equations along with the volume of fluid (VOF) method to track the location of the free surface at the air water interface. The numerical results are compared to existing experimental data from two flume experiments conducted as part of the European IMPACT project. Flow conditions in both experiments are complex due to the presence of hydraulic jumps, reflecting waves, and wet dry fronts. All three numerical models agree well with the water levels recorded in the experiments, especially for the triangular bottom sill case. The results from the depthaveraged model compare well with the experimental data and with the numerical results from the more sophisticated and computationally demanding 3D CFD models. The results from the CFD models show little improvement over those from the depth averaged model, with the exception of one location in the vicinity of a moving hydraulic jump.