中文摘要：

渠道中的突出建筑物对流场结构和污染物扩散过程有着重大影响，增加了预测污染物浓度分布的难度。为了探索使用数值模拟的方法来研究这种复杂流场下污染物扩散的适应性情况，采用大涡模拟（LES）方法计算设有2个挡板的渠道中的非定常流场和污染物浓度分布。通过Smagorinsky-Lilly亚网格模型计算亚格子应力，在已知流场信息下直接求解三维污染物对流扩散方程。大涡模拟得到的浓度值计算结果与试验数据吻合较好，其准确性明显高于雷诺应力模型的计算结果，从而表明大涡模拟模型在此类问题中的可行性。

英文摘要：

The prominent buildings in channels have a significant impact on flow field and pollutant dispersion, increasing difficulty in forecasting the distribution of pollutant concentration. In order to explore the adaptability of the numerical simulation method on cal- culating the pollutant dispersion under this kind of situation, a three-dimensional large-eddy simulation （LES） of flow structures and pollutant dispersion in a straight channel with two flow control baffles is performed. The subgrid scale stress tensor and the subgrid scale mass flux are simulated with Smagorinsky-Lilly sub-grid scale model. The calculated results of LES for the pollutant concentra- tion agree well with the experimental data and are more accurate than ones of Reynolds stress model. The successful simulaticm shows that LES is a feasible apt）roach to h r-.~l,.l^~_