The Design Of Nearshore Irregular Regional Wave Nested Model Based On MPI And Its Practical Application

Waves disaster is one of the most common marine disasters, Threat to people’s activities in theoceans and seas, coastal engineering, as well as people’s lives and property safety, it impact soserious on the development of marine economy. Detailed study of the numerical wave forecastinghas important practical economic significance.Parallel design based on the MASNUM (key laboratory of MArine Science and NUmericalModeling) wave model developed by First Institute of Oceanography of Static OceanicAdministrate, China. This design is start from the numerical implementation of complexcharacteristic equations, improve the computational efficiency. Taking into account the small areaof shallow water, The size of the wind zone, Shape of the coast and water depth importantinfluence of the evolution of the growth of the waves, Adopts the grid Nested method, Focus onthe area of interest encryption, Designed irregular boundary nested mode. The Purpose aboutimproving the flexibility and practicality of nested simulation in wave model for any shape of localareas, and to reduce the additional calculation and complexity of designing in the rectangularnesting is achieved.This nested wave model was applied to the region of Zhoushan and Ningbo in ZhejiangProvince through a triply nesting in order to simulate the wave in year of2011. In the smallestregion, an irregular open boundary was used which reduced the computation about45%related tothe rectangle open boundary. The experiment in big region is none nesting, but it will prepare theopen boundary conditions for the experiment of the nesting in middle region. There are2experiments in middle region, one without nesting and one with nesting from big region. Thenesting one is designed with a regular rectangle open boundary and it also provides the irregularopen boundary conditions for the nesting experiment in small region. The results of theexperiments in middle region indicate that the difference due to nesting is bigger near the openboundary which reached to more than0.5m; compared with the observation from satellite, theerror of significant wave height is reduced about30%because of the nesting; the simulatedaveraged and maximum wave height are0.7m and3.6m in summer time from the experimentwithout nesting, while they are1.0m and7.1m from nesting one which is much closer to theresults of1.5~2.0m and5.0~10.0m from historical observations. These results show that thenested model is feasible to regular nesting of wave model with the rectangle open boundary. For the small region, there are also2experiments, one without nesting and the other one with nesting.The open boundaries for them are designed as an irregular shape. As the result, the simulated wavedirection from the nested wave model in smallest region shows that the waves are mainlypropagated from the outer seas during May to August,2011and it is different with those results inthe one without nesting; the difference of the significant wave height is greater than1.0m duringJune to July, and the simulated wave periods from nesting experiment are generally larger than theone without nesting and the maximum reaches to8s. In a conclusion, this nested wave modelwhich is workable for the open boundary with a regular rectangle or an irregular shape can providea better simulation results in the same computational conditions. The results at the inner region ofcomputation domain will be improved because the information of swell from open oceans can bewell represented by the nesting at open boundary. It also indicated that this model is capable to beapplied for the wave simulation or predictions in the realistic and complicated coastal regions withan improved performance.