The Impact Of Topography And Land Use On Multi-scale Simulation For Near Ground Wind Field Of Typhoon

Typhoon is one of the important disasters affecting China's coastal areas,so restore the near ground typhoon wind field and study the disaster-causing mechanism of the structure under typhoon,it is of great significance to provides reference for building location selection and wind-resistant design.The wind direction and wind speed after typhoon landing are mainly affected by topography and land use.Because of the limitations of measured instruments,the measured typhoon wind field data are very rare.Numerical simulation became an important method for typhoon research.At present,WRF(Weather Research and Forecast)is commonly used in civil engineering field to simulate typhoon,which focuses on mesoscale typhoon simulation,while CFD(computational fluid dynamics)has more advantages in fine simulation of near ground wind field.Therefore,based on these two methods,this thesis aims to improve the simulation accuracy of the typhoon near ground wind field,and systematically studies the influence of topography,land use on the accuracy of typhoon simulation.In this thesis,typhoon "Mujigae" and "Hato" are simulated using five resolution topographic data to study the influence of terrain resolution on WRF simulated typhoon wind field.The elevation difference of topograph ic data with different resolution in WRF and its influence on typhoon track and intensity are analyzed.Comparing the difference between the elevation of the terrain data of different resolutions,10 m height wind speed at site,the wind speed of the typhoon "Hato" Shenzhen site,the wind direction of the typhoon "Hato" Shenzhen site and measured values.The results show that the high-resolution topographic data can more accurately represent the elevation of complex terrain and improve the simulation effect of typhoon track and 10 m height wind speed.Under the same conditions,the increase of terrain resolution does not affect the calculation efficiency,and the terrain data of 1 s performance better.In order to clarify the influence of land use on the acc uracy of typhoon wind field simulated by WRF,this thesis uses the land use data of 8 years int erval to simulate the typhoon "Rammasun","Mujigae" and "Hato".The differences before and after the update of land use data were analyzed,and found some land use proportions changed significantly.At the same time,the typhoon track and station wind speed before and after the land use data update are compared.The results show that the land use is not the main factor affecting the typhoon track,but it has significant impact on station wind speed.In this thesis,the parameter independence of the blocking rate,mesh size,inlet boundary condition and transition zone length in the CFD model is Researched,obtains the following conclusions: 1)Computational domain blocking rate ? 5%,2)The Horizontal mesh size is 30 m,The first layer height of the vertical grid is 1 m,and the growth rate is 1.09,3)The velocity inlet is adopted all around,4)The length of transition zone is chosen according to the terrain complexity.The above conclusions can provide reference for CFD simulation of complex terrain wind field.