Modeling Dam-Break Flows Using a 3d Mike 3 Flow Model

Dam-break flows usually propagate along rivers and floodplains. However, the majority of existing threedimensional (3D) models used to simulate dam-break flows are only applicable to fixed beds. In this model, the common 3D shallow water equations are modified, so that the bed evolution on the flood wave propagation can be considered. These equations are based on the numerical solution of the three-dimensional incompressible Reynolds averaged Navier-Stokes equations invoking the assumptions of Boussinesq and of hydrostatic pressure. Thus, the model consists of continuity, momentum, temperature, salinity and density equations and it is closed by turbulent closure scheme. For this 3D model the free surface is taken into account using a sigma-coordinate transformation approach. The model employs an unstructured finite volume algorithm. A predictor–corrector scheme is used in time stepping, leading to a second-order accurate solution in both time and space. The model was verified against results from existing numerical models and laboratory experiments at the same time it was used to simulate dam-break flows over a fixed bed in the predicted flood wave speed and depth. The results indicate that there is a good correlation between the dam-break flow predictions made over a fixed bed and existing numerical models and laboratory experiments.

Mike 3 flow model FM, dam break flow, numerical modeling, water level