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中文核心期刊

近地面大气湍流平均动能耗散率测量与分析

Measurement and analysis of turbulent mean kinetic energy dissipation rate in the atmospheric surface layer

  • 摘要: 用三维超声风速计测量了合肥地区风速脉动和温度脉动数据,并用二阶和三阶径向风速结构函数以及相似理论估算了湍流动能耗散率,估算结果基本一致. 其与稳定度相关性分析表明. 在大气处于中性条件下,湍流动能耗散率最大,并随| z/L |值增大而下降; Kolmogorov耗散尺度\eta 与\varepsilon ^1 / 4成反比,其与稳定度z/L的变化趋势与\varepsilon 随z/L的变化趋势正好相反; C_n^2 在大气处于中性条件下最小,并随| z/L |值的增大而增大,但在不稳定条件下C_n^2 增大得更快. 热力湍流内尺度不能用湍流动能耗散率\varepsilon 进行计算,而应引入与温度\theta 梯度有关的耗散率\varepsilon _\theta .

     

    Abstract: The triaxial sonic anemometer velocity and temperature flucturations were measured in the Hefei zone. Third order and second order structure functions and similarity theory were used to estimated the mean kinetic energy dissipation rate, which results were almost same. Correlation analysis with stability parameter show that maximum kinetic energy dissipation occurs at neutral condition and its value decreases with | z/L| . Because Kolmogorov microscale \eta is inverse dependence on \varepsilon ^1 / 4, which changing tendency with stability parameter is just reversely. Minimum C_n^2 occurs at neutral condition as well and increases wih | z/L |, however it increases more quick in unstable conditions. Thermal turbulence inner scale can not been calculated by kinetic energy dissipation rate \varepsilon , it may be decided by \varepsilon _\theta which connected with temperature gradient.

     

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