Numerical wave breaking with macro-roughness

This paper reports on a numerical investigation of solitary wave breaking over a sloping bottom covered with macro-roughness elements. Wave breaking is simulated by solving Euler equations with a two phase incompressible flow model. The hyperbolic system of the conservation laws is solved with a finite volume discretization on an unstructured grid. An artificial compressibility approach allows the use of a fully explicit scheme for an efficient parallel implementation. The numerical model is based on a low Mach number preconditioning and a second order Riemann solver. Several test cases are performed to analyze the role played by macro-roughness on the breaking dynamics. The influence of the macro-roughness elements on the solitary long wave breaking is shown to depend on two dimensionless ratios D/A and H/A, where D, H and A are the separation distances between the macro-roughness elements, the height of the elements and the wave amplitude, respectively. Significant effects are observed for large values of D/A and H/A. The successive cycles of impact/splash-ups/rebounds are strongly impaired. Three-dimensional wave breaking simulations are presented, showing the robustness of the method for modeling complex wave-structure interactions.