Abstract The interaction between the turbulent boundary layer and wake behind various types of two-dimensional cylinders is examined based on the velocity measurements by hot-wire anemometry and particle image velocimetry. Three types of cylinders, such as circular, square, and 1:5 rectangular cylinders, of two different diameters of 5 ​mm and 10 ​mm were employed in this study. The streamwise velocity distributions of the wake flow showed that its width is sustained in the streamwise direction within the boundary layer because of its interaction with the turbulent boundary layer flow. Interestingly, this phenomenon was observed regardless of the cylinder shapes. The momentum exchange in both spanwise and vertical directions showed that the advective momentum flux considerably contributes to momentum budget in the wake flow owing to the weak vertical flow formed within the boundary layer. Consequently, the spanwise width of the wake does not expand in the streamwise direction due to the alternation of the momentum budget. The results of this study can contribute to clarifying the effect of interaction between the wake and the turbulent boundary layer, as well as explain the sustaining mechanics of the low speed streaks formed within the turbulent boundary layer, even for different origins of the low-speed regions.

中文翻译：

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各类二维圆柱体后湍流边界层与尾流相互作用的实验研究

摘要 基于热线风速测量法和粒子图像测速法的速度测量，研究了湍流边界层和各种类型二维圆柱体后面的尾流之间的相互作用。在这项研究中使用了三种类型的圆柱体，例如圆形、方形和 1:5 矩形圆柱体，具有 5 毫米和 10 毫米两种不同的直径。尾流的流向速度分布表明，由于其与湍流边界层流的相互作用，其宽度在边界层内沿流向保持不变。有趣的是，无论圆柱形状如何，都可以观察到这种现象。展向和垂直方向的动量交换表明，由于边界层内形成的弱垂直流，对流动量通量对尾流中的动量收支有很大贡献。因此，由于动量预算的变化，尾流的展向宽度不会在流向方向上扩展。该研究结果有助于阐明尾流与湍流边界层相互作用的影响，并解释湍流边界层内形成的低速条纹的维持机制，即使对于不同的低速起源地区。