Numerical Simulation Study On The Characteristics Of 3D Downburst Flow Field

Dust storms are special disasters that occur in highly deserted areas of the soil.Their formation needs to meet three elements:sufficient sand source,strong wind power and unstable atmospheric circulation.However,the cause of the dynamic conditions of sandstorms and the shape of the dust-dust front are related to the dynamic structural characteristics of the downburst.Therefore,mastering the structural characteristics of the downburst wind field has laid a theoretical foundation for the study of sandstorms.At present,the study of sandstorms generally uses meteorological observation methods to explore its cause analysis and dynamic mechanism,while the numerical conditions for the dynamic conditions of sandstorms,that is,the ground strong winds generated by the downbursts are less.In this paper,the characteristics of steady-state three-dimensional downburst wind field are studied by numerical simulation.The characteristics of the downburst wind profile are discussed and the accuracy of the model is verified.The effects of different jet parameters:inlet velocity V_jet,outflow height H and inclination angle?on the characteristics of thunderstorm impact wind flow field are discussed.The main research content includes the following parts:1.The basic governing equations of downburst flow field are introduced in detail,and the corresponding turbulent closure model is introduced.The SST k-?is selected as the turbulent closure model in this paper,and the treatment method near the wall is introduced.2.Firstly,the accuracy and feasibility of the model are verified by comparing the calculated results with the experimental results of Chay et al.In addition,the downburst wind field has four wind profiles.The results show that the horizontal wind speed reaches the peak wind speed within a certain height near the ground,and then decreases with the increase of height,which is quite different from the exponential distribution of the atmospheric boundary layer wind profile.3.On the basis of the above,the effects of different parameters,such as inlet velocity V_jet,outflow height H and inclination angle?,on the wind speed profile of downburst are discussed.The results show that the inlet velocity V_jet has little influence on the vertical wind profile of horizontal wind speed,and the outflow height H and inclination angle?have more significant influence on the vertical wind profile of horizontal wind speed.