The coast's natural processes always affect the border between sea and beach and create different changes and transformations, differing with time and situation. The construction of some marine structures to deal with the waves, due to inconsistencies with environmental protection, disrupts the natural cycle in these areas. Therefore, to protect the coasts, environmental friendly structures must be applied instead of complex structures. In the present study, an environmental friendly flexible breakwater was considered as an alternative to rigid breakwaters for wave energy dissipation and beach protection. This type of breakwater reduces construction time and costs, as well as eases the installation and operation. This type of breakwater works differently from other models due to the range of motion, realating to how it is connected to the base and the structure's ability to move easily. Therefore, in the present study, analytical, numerical, and experimental modeling of this structures under the influence of coastal waves were performed. In analytical modeling, the structure was assumed as a uniform beam with a length l, horizontally moving over three different combinations of supports. The amount of displacement of the structure was calculated, applying the waves forces applied on the structure. Then, by employimg the Hamilton method, the principle of equilibrium and by interpolating the motion of the structure, the amount of displacement of the structure was obtained as a function of time and space. To study the effect of this motion on the wave, by numerical modeling of the structure under the impact of displacement, the amount of vibration created by the structure was evaluated. Finally, considering the linear wave equations, using the principle of superposition, the impacts of incident and reflected waves on each other was investigated. To validate the analytical results, the results of a laboratory modeling were used. In numerical simulation, the fluid volume method was used for modeling the free surface. For this purpose, a rigid circular structure was simulated. ______________________________________________
