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η与ε^(1/4)成反比,其与稳定度z/L的变化趋势与ε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ε进行计算,而应引入与温度θ梯度有关的耗散率ε_θ.
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 estimate the mean kinetic energy dissipation rate, with almost the same results. Correlation analysis with stability parameter shows that the maximum kinetic energy dissipation occurs at a neutral condition and its value decreases with ｜z/L｜. Kolmogorov microscale η is inversely proportional to ε^（1/4）, while the changing tendency with stability parameter is just reverse. Minimum Cn^2 occurs at the neutral condition as well and increases wih ｜z/L｜, however it increases more quickly in unstable conditions. Thermal turbulence inner scale can not be calculated by kinetic energy dissipation rate ε, and it may be decided by εθ, which is related to temperature gradient.
出处
《力学学报》
EI
CSCD
北大核心
2007年第6期721-726,共6页
Chinese Journal of Theoretical and Applied Mechanics
基金
国家自然科学基金(40475010).~~
关键词
大气湍流
平均动能耗散率
稳定度
热力湍流
内尺度
atmospheric turbulence, mean kinetic energy dissipation rate, stability, temperature turbulence inner scale
