The classic approach of studying the wave interaction with coastal structures is performing physical model testing on a scaled model of the structure in a wave flume in the laboratory. During the last decade, numerical modelling has become a powerful and efficient research tool in the field of coastal engineering. In this paper the numerical model VOFbreak2, based on the Navier-Stokes equations and the Volume-Of-Fluid (VOF) technique for treating free surfaces, is presented which is capable of simulating the wave propagation and interaction with a variety of coastal structures. Two practical test cases illustrate features, advantages and limitations of the numerical model. In the first test case, wave propagation into a porous rubble mound breakwater and attenuation of the induced pore pressures is investigated. The second test case presents simulations of wave run-up and overtopping at an impermeable sea dike
