Numerical modeling of breaking waves over porous structures

Porous armour units are frequently employed to protect coastal structures, such as seawall or caisson breakwater, from wave attack. To determine the stability of the armour layer requires the knowledge of flow motions in porous media and the corresponding pressure and force fields. A numerical model has been developed recently by Lin & Liu (1998) to study breaking waves in surf zones. The model is further extended in this paper to simulate flow fields in porous media. A simple experiment of flow passing through a porous dam is first used to calibrate the model. With properly calibrated coefficients, the numerical model is then employed to simulate breaking waves overtopping a caisson breakwater protected by porous armour units. The calculated free surface displacement near the caisson breakwater is compared with measured data and reasonably good agreement is obtained.