A VISUAL INVESTIGATION OF WALL REGION IN TURBULENT FLOW
A VISUAL INVESTIGATION OF WALL REGION IN TURBULENT FLOW
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DOI：
10.1017/s0022112069000395
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发表时间：
1969-01-01
影响因子：
3.7
通讯作者：
BRODKEY, RS
中科院分区：
文献类型：
--
作者：
CORINO, ER;BRODKEY, RS
本研究的目的是调查湍流的流体运动非常接近固体边界，并创建一个物理图片，这些运动与湍流的产生和运输过程。开发了一种实验技术，该技术允许对非常靠近管壁的区域进行详细观察，包括粘性子层，而不需要将任何注射或测量装置引入流中。这项技术涉及将胶体大小的固体颗粒悬浮在液体中，并用高速运动摄像机拍摄它们的运动。为了提供更多的细节，我们放大了视野，观察到流体运动的特征随着离壁的距离而变化。小规模的低幅度的速度波动和周期性的流体元素渗透到该地区的位置进一步从壁的子层不断扰动。从一个薄的区域相邻的子层，流体元素定期向外喷射的中心线。在平均流和减速区之间的界面上，常常有一个高剪切区与这些事件相联系，而减速区则产生了喷出的元素。当喷出的元素进入这个剪切带，它与平均流相互作用，并产生强烈的，混乱的速度波动。这些喷射和由此产生的波动是壁区最重要的特征，并且被认为是湍流产生和维持的一个因素。
The objective of this study is to investigate for turbulent flow the fluid motions very near a solid boundary, and to create a physical picture which relates these motions to turbulence generation and transport processes. An experimental technique was developed which permitted detailed observations of the regions very near a pipe wall, including the viscous sublayer, without requiring the introduction of any injection or measuring device into the flow. This technique involved suspending solid particles of colloidal size in a liquid, and photographing their motions with a high-speed motion picture camera moving with the flow. To provide greater detail, the field of view was magnified.Fluid motions were observed to change in character with distance from the wall. The sublayer was continuously disturbed by small-scale velocity fluctuations of low magnitude and periodically disturbed by fluid elements which penetrated into the region from positions further removed from the wall. From a thin region adjacent to the sublayer, fluid elements were periodically ejected outward toward the centreline. Often there was associated with these events a zone of high shear at the interface between the mean flow and the decelerated region that gave rise to the ejected element. When the ejected element entered this shear zone, it interacted with the mean flow and created intense, chaotic velocity fluctuations. These ejections and resulting fluctuations were the most important feature of the wall region, and are believed to be a factor in the generation and maintenance of turbulence.