| The vertical 2D numerical wave models not only describes the instantaneous process of the wave interation with obstacles but also can give details of the current field, which is far more outstanding than the physical model and other traditional analyzing methods, it is thus of great importance to develop a numerical model of wave action on obstacles and to use it.The governing equations of the vertical 2D model are the Reynolds-averaged Navier-Stokes equations for incompressible viscous fluid. The Reynolds stress terms are closed by the k ?εturbulence transportation model. It can simulate small amplitude wave, Stokes wave, cnoidal wave, solitary wave and irregular wave acting on obstacles by source function wave generating method. It can also simulate wave-current motion inside porous structure such as rubble mound foundation. The free surface tracking method is the key technique in developing the vertical 2D numerical wave models. The VOF method is adopted to deal with the free surface. The main advantage of this model is its consideration for nonlinearity, viscosity and turbulence effect. The two-step projection method is used to solve the equations.The economical criterion to choose the more adapted structure type is very dependant on the water depth in the area to be protected because of its impact on the volume of material. The economical criterion remark has led engineeris to imagine new breakwaters located near the free surface where the energy flux is maximal. The new U-type breakwater is adoped. U-type breakwaters are supported on piles and the load from the waves are transferred to the seabed through these piles. An absorbing caisson at the left side of the structure is used in order to reduce the reflection. These type breakwaters can be used to deepwater and the cost is lower than the other breakwaters.The flow fields are investigated under different structure conditions by the vertical 2D numerical wave model. The U-type breakwater can reduce wave heights and protection shore or harbour shelters. |
