中文摘要：

针对大涡模拟涡粘性亚格子模式中使用网格尺度为特征尺度存在的不足,提出一种改进的亚格子特征尺度表达式,利用结合Sagaut混合尺度模式获得的改进模式与Smagorinsky模式、Germano模式和Sagaut模式等进行对比研究.时间发展混合层和中性大气边界层的大涡模拟结果表明,改进的有效亚格子特征尺度能合理反映亚格子脉动的时空分布特性,同时扩展了适用范围.在对耗散程度、流动演化过程、可解湍流强度和可解雷诺应力等方面的模拟,改进模式优于基准模式,表明亚格子脉动有效特征尺度在大涡模拟中具有一定的理论基础和广泛的应用价值.

英文摘要：

In the Sagaut mixed-scale model,an improved subgrid-scale （SGS） characteristic length, representing the scale of local energy-containing SGS motions, is proposed. Large-eddy simulations（LES） at temporal mixing layer and neutral atmospheric boundary layer indicate that by the improved SGS characteristic length, satisfactory spatial distribution of the SGS motions can be obtained and are closer to the results of direction numerical simulations（DNS）. Compared with the basic model, the modified model with the improved SGS characteristic length produces more accurate mean quantities and turbulent statistics. The results demonstrate its valuable and wide application to LES.