中文摘要：

运用大涡模拟计算了两个非对称复式断面明渠内的水流运动和污染物扩散,其中由亚格子尺度涡运动引起的亚格子应力与物质扩散通过Smagorinsky-Lilly亚网格模型模拟。将计算结果与文献中的激光多普勒流速计和激光诱导荧光技术测量的试验数据进行对比,结果表明,计算得到的流场结构和污染物浓度分布均较好地吻合于测量结果。模拟计算成功再现了实际明渠中观测到的横向浓度分布所呈现的显著双峰值的现象,分析计算数据表明,复式断面明渠中流向交替变化的强烈横向流动是产生这种现象的主要原因。

英文摘要：

The flow field and solute dispersion in two asymmetric compound channels were computed using large eddy simulation（LES） technique.The Smagorinsky-Lilly subgrid-scale models for the turbulent subgrid-scale stress and mass flux are employed to close the governing equations.The simulation results were compared with experimental data obtained by using laser Doppler anemometer（LDA） and Laser-induced fluorescence（LIF） in a small laboratory flume.The calculated flow field and pollutant concentration distribution are in good agreement with measurement results.A significant experimental phenomenon that lateral concentration distribution has two distinct concentration peaks in one of the channels is successfully predicted by LES.The cause of that phenomenon obtained by analyzing calculated flow field is the existence of strong alternative cross flow in the compound channel.