A new technique for estimating the stable weight of armor units on a submerged breakwater in wave-current coexisting field

The stable weight of armor units on a submerged breakwater considering nonlinear interaction among waves, current and submerged breakwater has been investigated in this study. An integrated technique for estimating the nonlinear wave and current forces on armor units and their minimum stable weight have been developed for the case of nonbreaking waves. The technique is mainly dependent on a numerical model, called BEM-FEM model. The model considers the wave deformation due to its interaction with porous but non-deformable structure over an impermeable seabed in a current filed. The results of the BEM-FEM model have been compared with some experimental results in order to evaluate the validity of the numerical model. The applicability of the BEM-FEM model has been used to evaluate the effect of using submerged breakwaters to improve the swimming conditions and decrease the net long shore transport of sand in the near shore zone in one of the Egyptian northern coastal resorts. The effect of breakwater size, hydraulic properties and current on the wave deformation and the dynamic forces on armor units has been examined. Also, the dynamic behavior of the submerged breakwater has been analyzed under different wave and current conditions to estimate the maximum wave forces acting on the armor units. Moreover, a new method has been proposed to estimate the distribution of the stable weight of the armor units on a submerged breakwater using Rufin stability models. It has been found that the factor of safety for computing the minimum stable weight using some traditional formulae ranges between 2 to 3.