湍流模型对预测街道峡谷污染物扩散的影响

文章选取标准k-ε湍流模型、RNGk-ε湍流模型、realizablek-ε湍流模型和单方程Spalart-Allmaras涡黏系数模型对街道峡谷附近的流动和汽车尾气污染物扩散进行了模拟,并与风洞试验值进行了比较,结果表明,4种模型对街谷壁面的浓度预测在趋势上与试验值基本一致,Spalart-Allmaras模型的预测效果最好,realizablek-ε模型预测最差,而标准k-ε模型和RNGk-ε模型的预测介于其间;RNGk-ε模型和realizablek-ε模型的修正作用在预测建筑物尖角和顶部附近的流动处有所体现,但对街谷内浓度分布的预测仍不如标准k-ε模型;本文从流场分布的特点对4种模型的浓度预测差别进行了解释,证明了壁面浓度与其附近的速度和湍流黏性系数的分布相对应。

Effect of Turbulence Models on Prediction of Pollutant Dispersion in Street Canyon

Four turbulence models including standard k-ε,RNG k-ε,realizable k-ε and Spalart-Allmaras were chosen to simulate the flow and vehicle exhaust pollutant dispersion in street canyon.Results were compared with the wind tunnel test and a general agreement was obtained between numerical and experimental data.In these four models,Spalart-Allamaras was the best in agreement with the experimental data,and the standard k-ε and RNG k-ε were acceptable,while realizable k-ε was the worst.The model prediction performance of the concentration was closely related with the flow field.