Reflection of water waves by sloping porous structures

The phenomena of water wave interaction with a semi-infinite sloping beach or a sloping dam backed by an impermeable barrier are analyzed. The analyses are based on the potential theory and theoretical solutions are obtained for the reflection coefficients. The behaviour of wave numbers satisfying the porous-medium dispersion relation is first studied. It is found that the wave number characteristics are strongly influenced by the wave-effect parameter and the friction factor. The reflection and dissipation of a monochromatic surface wave by a sloping beach or dam are then investigated. It is shown that by varying the angle of the slope alone, the reflection coefficient of the structure shows a number of local maxima and minima whose exact locations vary with the wave-effect parameter and the friction factor.