Geometrically open filters in breakwaters

Model tests on wave effect on a sand layer under a rock armour layer. Nine process based model tests have been performed with regular waves with a height of 10 cm and a period of 1.2 s. The first two experiments were used to tune the test setup. The other seven experiments had different thickness of the filter layer (df) and different grain size (Df50) of the filter material. Due to limitations in time and availability of the facilities other parameters then the df and Df50 such as the wave height and the slope steepness have been kept constant at a value which is typical for breakwaters or wind waves.