A numerical wave flume based on the Navier-Stokes equations to describe the hydrodynamic processes of the interaction of waves with a seawall is presented. The model is validated against experimental data obtained in a 72.5 m long and 2.0 m wide wave flume with a model scale of 1:5. The results demonstrate that the numerical model can describe with good accuracy the wave generation, propagation and transformation over the slope as well as the pressure time series on the breakwater. © 2016 Taylor & Francis Group, London.