Hydrodynamic characteristics of double permeable breakwater under regular waves

The wave transmission, reflection, and energy dissipation of the double vertical wall with permeable lower part (horizontal slots) were experimentally and theoretically studied under normal regular waves. The effect of different wave and structural parameters on the hydrodynamic characteristics was investigated e.g. the wave length, the upper part drafts, the lower part porosities, and the space between the double walls. Also, the theoretical model based on an EigenFunction Expansion Method was developed to study the hydrodynamic breakwater performance. In order to examine the validity of the theoretical model, the theoretical results were compared with the present experimental results. Comparison between experiments and predictions showed that theoretical model provides a good estimate to the wave transmission, reflection, and energy dissipation coefficients when the friction factor f = 3. The hydrodynamic efficiency of the proposed breakwater is strongly affected by changing the following: (1) The two upper part drafts together, (2) The upper part draft of the first barrier, (3) The two lower part porosities together, (4) The lower part porosity of the first barrier.