Physical model tests of the notional permeability on breakwaters

This model is designed from the fourth construction of Van der Meer. The construction of model 5 is build with a top layer, filter layer 1 and a permeable core with the same material of filter layer 2 of model 3A and model 4. The results of this research show that the influences of the notional permeability P exists of the ratio of the armour layer thickness and the thickness of the second filter layer.

If the layer thicknesses are equal the value for notional permeability P is 0.38, which follows from model 3A. If the second layer has an infinite thickness (permeable core), the value for notional permeability P is 0.45, which follows from model 5. The value of the notional permeability P of model 5 corresponds to the design calculations of the computer model HADEER.

Van der Meer discovered using this computer model that the ratio of dn50a/ dn50f = 5 has a value on the notional permeability P of 0.43 –0.44. During this research, while using two different methods, a value of the notional permeability P of 0.45 was calculated.