论边界层中的大气扩散PDF模式

基于大气扩散Ｋ理论，用作为风速脉动均方差和拉氏时间尺度函数的湍流交换系数，得到了直接利用风速脉动几率密度而不用扩散参数的大气扩散ＰＤＦ模式。分别研究了对流边界层上升气流区与下降区垂直速度的统计特征，求得双正态ＰＤＦ模式。在给定ＣＢＬ自身参数如对流特征速度ｗ＊，顶高ｈｉ和源高度上的平均风速时，该模式计算出的无量纲浓度分布与室内外测试结果一致。

ON THE PDF MODELS FOR ATMOSPHERIC DIFFUSION IN BOUNDARY LAYER

Based on atm ospheric diffusion K-theory with its turbulent exchang ecoefficient as a function of the lagrangian time scale and standard variance of the turbulence in atmosphere,the atmospheric disper sion PDF models are obtained,in which the statistics of wind speed are directly used as its parameters instead of traditional dispersion paraeters.The bi-gaussian PDF is derived,in convective boundary layer (CBL ),from the statistics of vertical velocity in both of the downdrifts and updrif tsregion that are investigated theoret ically in the other part of this paper.In CBL,if its driven parameters such as the convective velocity scale w^*,the mixing depth h_i and the average wind speed atrelease level were given,the non-dim ensionalizing distribution of the concent ration calculated from the PDF modelgiven here are fairly agree with that given from the measurements in CONDORS experiment or the resulting from numerical simulation.