The Research And Application Of Combined Refraction-diffraction Wave Model Nearshore

The combined refraction-diffraction wave model is used in the computation of the designed wave factors around the sea bank of Xunshan Power Plant in Sanggouwang. Based on it, the model considering current changes is further explored and the effect of the wind within the computation area on the wave change is discussed.With the development of sea projects, wave as an important environmental factor, is well studied. This thesis reviews the development and application of wave numerical model and illustrates the feasibility and great value of the research on it.The combined refraction-diffraction wave model based on the mild slope equation, which is derived by Jiang Decai et al, is an important kind of wave models. With the improvement in the last decades, these models have been successfully used in the computation of waves for coastal engineering and others. Following a review, this thesis begins with the slope equation, deduces the difference scheme, introduces the dispose of the boundary conditions, and illustrates the basic principle and introductions.Practice is the sole criterion of truth. The combined refraction-diffraction wave model is used in the computation of the designed wave factors around the sea bank of Xunshan Power Plant. Through the wave data of each year in Chengshantou and Shidao sea station, making out the boundary conditions, the wave fields of multi-year return-period in various water levels from various directions is obtained. The characters of different directions is specified and wave heights at the key points around the sea bank is given out.Base on the descriptions above, the change of wave in the current which is simulated from ECOM is considered, but the change is very little. Further more, the wave change in assumed, even currents is studied, making out the conclusion that when the direction of current is the same as the direction of wave, the wave height get bigger; on the contrary, the wave height get smaller.Wind is another important factor affecting the wave. The formula of shallow water wind wave growth is used in the computation. But in this project the range of the sea area is not very big and the net step is not very long, the affection of the wind in this computation can be ignored. But in other occasion when the computing range is big enough, the wind effect must be considered.The computation of wave in this thesis is based on the model created completely by our Chinese people. In this thesis the affection of current and wind is fully considered. The work in next step is to deal with the relationship of wave length and the net step, and consider more factors affecting the wave, to make the combined refraction-diffraction wave model more comprehensive and create more values.