一个研究街道峡谷流场及浓度场特征的三维数值模式

目前，研究街道峡谷内流场及机动车排放污染物的扩散行为特征所采用的主要方法为：采用野外测试法和物理模拟法，而采用三维数值模拟方法研究此问题的工作很少。本文创建了一个研究微尺度街道峡谷内流场及机动车排放污染物扩散特征的三维数值模式，即首次采用伪不定常方法，利用K——E闭合方案，建立了一个模拟城市街道峡谷内流场及污染物扩散特征与街道峡谷风场、街道几何结构及两侧建筑物高度对称性之间的复杂关系的三维数值模式。经过与实际监测资料及风洞实验对比，结果表明此三维模式具有较好的模拟精度，能够很好模拟峡谷内的风场及街谷几何结构对街道峡谷内流场及浓度场特征的影响，有很强的实用性。

A Numerical Model on Flow Field and Concentration Distribution in An Urban Street Canyon

At present,the main method on flow field and concentration distribution within an urban street canyon is observation and experiment.In this article,in order to predict the dispersion characteristics of vehicle emission pollutants in an urban street canyon,a three-dimension numerical model was developed based on artificial compressibility method and a K-E model.This three-dimension numerical model has been evaluated using the database from a set of street canyon experiments carried out in an urban street canyon of Lanzhou city in July 1995,it shows that the numerical model is accurate and useful for predicting the wind distribution and the air quality within an urban street canyon under the terms of different wind speed and wind direction,street canyon's height/width ratio and different building symmetry.