Wave-dissipating Characters Of Permeable Plate Breakwater

With the continuous development of world trade,the number and tonnage of berths in the world are also growing.However,most wharfs require breakwaters,which can cover them and ensure the stability and working conditions in the port area.The traditional non-permeable breakwater ensures the tranquility condition by directly blocking the wave entering the harbour basin,but it is not conducive to the exchange of water inside and outside the sheltered water area,and may result in the high flow rate at the breakwater gate.In order to solve these problems,a permeable plate breakwater structure has been proposed.However,the wave-dissipating characters of this structure have not yet been fully grasped.In this paper,a combination of physical model test and numerical simulation is used to carry out a series of research work on the wave-dissipating characters of this structure.The work and conclusions are as follows:(1)The sectional model test was carried out in the two-dimensional wave flume using the gravity similarity criterion.The experimental process was observed and found that the two-dimensional regular wave will transform into three-dimensional irregular wave after passing through the permeable plate breakwater structure.In the case of small wave height,the wave will break between the plates.When the wave hight is large,the water that stays on the uppermost layer will slant downward into the bank,and this water will have an adverse effect on the water surface.Through the physical model test,the wave-dissipating effect of the permeable plate breakwater is intuitively recognized.The test also provides a basis for the verification of the numerical model.(2)Based on the fluid simulation software Fluent,a numerical wave flume was established,and a correction method was proposed for the attenuation of the wave height caused by numerical viscosity,and the wave-making and wave-dissipating performance of the numerical wave flume were verified.(3)Using the control variable method,a series of numerical models for the interaction between the wave and the permeable plate breakwater structure are established.The numerical model is verified by the results obtained by the physical model test.The hydrodynamic characteristics of wave and permeable plate breakwater are analyzed(including spectral analysis and flow field analysis).It is found that the transmitted waves may contain high-order frequency components,and the wave-dissipating mechanism of permeable plate breakwater is putting limitations on the vertical movement of water particles.The factors affecting the wave-dissipating characters of the permeable plate breakwater structure are analyzed.The parameters of wave-dissipating characters include transmitted wave height,transmission coefficient,reflection coefficient and energy consumption coefficient.The analysis shows that the incident wave height and the relative plate width are the main factors affecting the wave-dissipating characters of permeable plate breakwater structure.(4)Referring to the wave conditions of Yantai LNG project in Shandong Province,combined with the results of numerical simulation,two optimization forms of permeable plate breakwater structure are proposed,and the two optimization types are compared with the original wave-dissipating characters.The optimized form has a certain degree of advantage over the original form.In summary,the wave-dissipating characters of the permeable plate breakwater structure are analyzed by physical model test and numerical simulation.The results of the physical model test are used to verify the numerical model,and the wave-dissipating characters of the permeable plate breakwater have been further understood.Two optimization types are proposed according to the engineering practice,making it more suitable for practical engineering.