Numerical Simulation Of Wind And Wave In South China Sea Based On Different Typhoon Field Model

Typhoon is a destructive disaster marine weather system, the gale and giant waves in typhoon process bring great threats to navigation, marine aquaculture, ocean engineering and nearshore construction, cause large economic loss to coastal areas while they also influence the sustainable development of regional economy. Therefore in coastal areas, effective simulation and forecast of typhoon winds and typhoon waves are of great significance to the assessment to influence sphere and degree,the reasonable planning of economy, effective disaster prevention and mitigation, and disaster prevention design for engineering structure.The reliability of typhoon field is one of the key factors, which currently affect the accuracy of numerical forecasting and hindcasting of typhoon wind and wave. This thesis chooses four kinds of gradient wind field models, contrastive analyzes parameters affecting the wind field models, verifies their validity to typhoon wind field simulation in the south China sea. Comparing to the wind speed of measuring points indicates, Holland gradient wind field model, due to considering the structure parameter b which adapt to changes in the typhoon intensity, simulation precision is the highest.To further verify the validity of the typhoon wind field simulation, the result wind models have been respectively taken as driving wind field of the third-generation wave model SWAN. The contrastive analysis between simulated results and measured data shows that, the SWAN model can be adapted to complex environment in the south China sea by choosing appropriate control parameters, and draw the conclusion that taking Holland wind field as driving wind field, simulated values and measured values fits better. Further verifies that the Holland wind field has better applicability in typhoon wind filed and typhoon wave numerical simulation in the south China sea.Gradient wind model is some kind of an approximation for typhoon field, and not considering the asymmetry of typhoon field and the boundary layer friction effect, etc, may cause simulation errors. As a result, this thesis presents a dynamic typhoon finite element model in the planetary boundary layer. This model, which belongs to the steady-state dynamical model, basing on Euler coordinate, considers coriolis force, friction effect of typhoon wind field in the boundary layer. Computational domain takes moving typhoon center as the origin of coordinates; the moving rectangular coordinate system moving with typhoon is established. It takes the origin as a starting point, set up triangle mesh from the inside out, uses the galerkin method to discrete each item of the typhoon field dynamic equation in the planetary boundary layer, gets nonlinear equations of this dynamic equation. Solving them can get the wind speed distribution of typhoon wind field at a certain time. The feasibility of using finite element method to solve the typhoon field dynamic equation in the planetary boundary layer has been verified primarily.