The rough-wall turbulent boundary layer from the hydraulically smooth to the fully rough regime
The rough-wall turbulent boundary layer from the hydraulically smooth to the fully rough regime
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DOI：
10.1017/s0022112007005502
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发表时间：
2006-11
影响因子：
3.7
通讯作者：
M. Schultz;K. Flack
中科院分区：
文献类型：
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作者：
M. Schultz;K. Flack
粗糙壁边界层的湍流测量，并与光滑壁的湍流测量进行比较。粗糙壁实验是在几何上类似于Shockling，艾伦& Smits（J. Fluid Mech.vol.564，2006，p.267）使用的珩磨管粗糙度的三维粗糙表面上进行的。目前的工作涵盖了宽的雷诺数范围（Re θ = 2180- 27100），对于单个表面，从水力光滑流态到完全粗糙流态，同时保持粗糙度高度为边界层厚度的一小部分。在这项研究中，均方根粗糙度高度至少比边界层厚度小三个数量级，卡门数（δ+），代表气流中最大和最小湍流尺度的比值，高达10100。粗糙壁和光滑壁的平均速度分布显示出显着的相似性，在外层使用速度缺陷标度。雷诺应力和高阶湍流统计也显示出良好的协议在外层。结果提供了强有力的支持粗糙壁的外层相似性的概念，其中有一个大的分离粗糙度长度尺度和最大的湍流尺度的流动。
Turbulence measurements for rough-wall boundary layers are presented and compared to those for a smooth wall. The rough-wall experiments were made on a three-dimensional rough surface geometrically similar to the honed pipe roughness used by Shockling, Allen & Smits (J. Fluid Mech. vol. 564, 2006, p. 267). The present work covers a wide Reynolds-number range (Re θ = 2180–27 100), spanning the hydraulically smooth to the fully rough flow regimes for a single surface, while maintaining a roughness height that is a small fraction of the boundary-layer thickness. In this investigation, the root-mean-square roughness height was at least three orders of magnitude smaller than the boundary-layer thickness, and the Kármán number (δ+), typifying the ratio of the largest to the smallest turbulent scales in the flow, was as high as 10100. The mean velocity profiles for the rough and smooth walls show remarkable similarity in the outer layer using velocity-defect scaling. The Reynolds stresses and higher-order turbulence statistics also show excellent agreement in the outer layer. The results lend strong support to the concept of outer layer similarity for rough walls in which there is a large separation between the roughness length scale and the largest turbulence scales in the flow.