二维岛屿尾流近区流动参数的分布特性

为了深入研究尾流近区的流动规律 ,以便对岛屿后方的污染物混合输移特性有更清晰的了解 ,采用数字粒子图像测速 (digital particle image velocimetry,DPIV )技术 ,在恒定来流的工况下 ,分别对圆柱和正弦形状岛屿在尾流近区的速度分布进行了比较详细的测量 ,获得了大量的数据。文中着重从相似性的角度 ,对流速在长时间 (尾流摆动的一个周期 )内的平均值进行了分析。结果显示 ,沿程各断面的此种平均流速在归一化后具有一定的相似性 ,但是各断面归一化的紊动参数分布有很大的差别

Flow characteristics in the near wakes behind 2-D islands

The flow mechanisms in near wakes must be known to better understand the characteristics of pollutant mixing and transport behind islands. The velocity fields behind cylindrical and sinusoidal shaped islands were measured for steady inlet flow using digital paricle image velocimetry (DPIV). This paper illustrates the similarity of the mean velocity over a long period of time (the period is a cycle of the Karman vortex shedding). The results show that the averaged velocity distribution in the near wake region obeys the similarity law after normalization, but the normalized turbulence parameter distributions in these regions are quite different.