对流边界层中公路线源扩散的Monte-Carlo法模拟

MONTE-CARLO ATMOSPHERIC DIFFUSIVE MODEL AND ITS SIMULATION OF LINE SOURCE IN CBL

开发了一个Ｍｏｎｔｅ－Ｃａｒｌｏ大气扩散模式且引入了一种检验随机数质量的填充二维点格的方法。通过与水槽试验资料对比，说明该模式具有较好的模拟效果。用该模式模拟公路线源的大气扩散，结果表明，高架路和一般公路的污染在地面浓度上差异较大，而在垂直方向上差异较小。高架路引起的地面浓度值和扩散范围都较一般公路的大。垂直方向上尤其是２０米以上二者基本没有差异，浓度较大值都在５０～１００米以下。结合箱模式的思想，导出了一个适用于城市汽车尾气污染估计的实用公式。

A Monte-Carlo diffusive model is developed and the random number quantity is tested by loading two-dimensional dot grids. Comparing the simulative result against the convective box shows the good simulation effect of the model. The atmospheric diffusion of the line source is simulated using this model, showing that the ground concentration is much different and the vertical concentration difference is small between the flyover and the highway. The ground concentration and the diffusive range caused by the flyover are larger than those caused by the highway. There is almost no difference in vertical direction, especially above 20m and larger concentration is positioned below 50-100m. Based on the idea of box model, a practical formula is derived that is applicable for estimating tail gas from urban vehicles.