Numerical simulations of dam-break waves impacting a rigid wall

Tsunamis, landslides and the failure of artificial dams can be modelled as dam–break waves, unsteady flows sometimes characterized by shock–wave fronts. During their propagation these waves may interact with obstacles, eventually causing destruction and losses on nearby areas. The evaluation of the front propagation and of the impact force is of utmost interest for risk mitigation. We performed a series of both 3–D, non–hydrostatic, Rey nolds–Averaged Navier–Stokes (RANS) and Large Eddies numerical Simulations (LES) of laboratory dam–break experiments using the Volume of Fluid (VOF) approach. We carried out experimental tests in a prismatic, rectangular channel locked downstream by a vertical wall; we measured the free surface configuration and the force by the wave on the downstream wall to validate the numerical results. Numerical predictions show strong 3–D effects developing nearby the wall characterized by air entrainment and free surface deformation. The VOF approach for tracking the free surface successfully allows to catch these flow features and the free surface evolution shows a good agreement with both RANS and LES simulations. Results are compared with 3–D, hydrostatic, depth–averaged numerical simulations. Although the latter cannot capture the 3–D features of the flow, they are able to predict both the impact time and the magnitude of the impact force peak.