A Numerical Study Of Wave Environment Near Islands And Reefs

Wave propagates from deep water to shallow water near islands and reefs and generates diffraction?refraction and reflection due to complex seabed terrain and islands shelter,which is a very complex process.Wave energy also will be dissipated by wave breaking and bottom friction.This paper is aim to investigate the calculation method of typhoon wave and wave evolution law near target islands based on wave numerical model?model test and measured data in real sea.First,the nested interfaces of SWAN model and WWIII model are modified in order to nesting calculate typhoon "Haiou" with smaller scale grid and the comparision result shows that the result of nested computation is obviously better than result calculated by WWIII model only.Analyze the evolution process of double peak wave spectra measured at measurement point with the wind nephogram at the corresponding moment.Then,investigate the wave propagation law near target islands by conducting a model test whose scale ratio is 100:1 in DaLian University of Technology.The experimental results and SWAN results show that SWAN model is accurate in most area but still having defects on simulating waves on very shallow area and region of strong diffraction.Finally,a mathematical model of inverse problem is proposed,which takes advantages of measured terrain near islands,one measurement point and its first three order spectral moments to retrieve wave spectra in far field.SWAN model and genetic algorithm are used to solve this mathematical model.Several examples based on calculated data of SWAN and model test data are carried out to validate this method.The results show that this method is practical,which can retrieve wave parameters in far field successfully.