To investigate influence of nappes induced by tsunamis flowing over breakwaters, a single-phase flow model, CADMAS-SURF/3D and a two-phase flow model, FSSM are applied to existing hydraulic experiments. From comparison, the single-phase flow model can predict the hydraulic experiments with sufficient accuracy in terms of water surface elevation and the shape of a nappe. In contrast, the two-phase flow model underestimates water surface elevation at the seaward edge of the breakwater in the presence of a parapet because a decrease in pressure due to flow separation causes an increase in flow velocity on the breakwater. Furthermore, both models give different distributions of pressure acting on the landward side of the breakwater probably because nappe-induced vortices are not computed with sufficient resolution.
