Transient numerical simulation for unsteady-state downburst winds
WANG Zhisong1,2,WANG Chao3,LIU Yanan1,LI Zhengliang1,2
1. School of Civil Engineering, Chongqing University, Chongqing 400045, China;
2. Key Laboratory of New Technology for Construction of Cities in Mountain Area, Ministry of Education, Chongqing University, Chongqing 400045, China;
3. Hunan Provincial Architectural Design Institute, Changsha 410001, China
Impinging jet is one of the most commonly used simulation methods in studying the wind field of thunderstorms. Most of the previous physical tests and numerical simulations assume that the inlet velocity of the jet does not change with time, while the sinking velocity of downburst winds is continuously changing with time actually during its whole lifecycle, it gradually increases to the maximum value and then decreases in general. For wind-resistant design of significant engineering structures, it’s necessary to acquire the temporal profiles of downburst wind speed in its whole lifecycle. Here, a three-dimensional full-scale impinging jet was taken as a wind field model of downburst. The decay functions for the inlet jet velocity were given for the actual downburst，and numerical simulation was performed by adopting the large eddy simulation(LES) to acquire an unsteady-state wind field where the intensity decay information of downburst was presented. The simulation results showed that the unsteady wind field of downburst can be well simulated with this proposed method, and the results are correlated well to Andrews AFB recorded ones. These results laid a foundation for further studying wind load characteristics of unsteady downburst.
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