Balakumar B J, Adrian R J
Department of Theoretical and Applied Mechanics, University of Illinois, Urbana, IL 61801, USA.
Philos Trans A Math Phys Eng Sci. 2007 Mar 15;365(1852):665-81. doi: 10.1098/rsta.2006.1940.
Large-scale motions (LSMs; having wavelengths up to 2-3 pipe radii) and very-LSMs (having wavelengths more than 3 pipe radii) have been shown to carry more than half of the kinetic energy and Reynolds shear stress in a fully developed pipe flow. Studies using essentially the same methods of measurement and analysis have been extended to channel and zero-pressure-gradient boundary-layer flows to determine whether large structures appear in these canonical wall flows and how their properties compare with that of the pipe flow. The very large scales, especially those of the boundary layer, are shorter than the corresponding scales in the pipe flow, but otherwise share a common behaviour, suggesting that they arise from similar mechanism(s) aside from the modifying influences of the outer geometries. Spectra of the net force due to the Reynolds shear stress in the channel and boundary layer flows are similar to those in the pipe flow. They show that the very-large-scale and main turbulent motions act to decelerate the flow in the region above the maximum of the Reynolds shear stress.
大规模运动（LSMs；波长高达2 - 3个管道半径）和超大规模运动（波长超过3个管道半径）已被证明在充分发展的管道流动中携带超过一半的动能和雷诺切应力。使用基本相同的测量和分析方法的研究已扩展到通道流和零压力梯度边界层流动，以确定这些典型壁面流动中是否会出现大尺度结构，以及它们的特性与管道流动相比如何。超大规模结构，尤其是边界层中的那些，比管道流动中的相应尺度要短，但在其他方面具有共同的行为，这表明除了外部几何形状的影响外，它们是由相似的机制产生的。通道流和边界层流动中由于雷诺切应力产生的净力谱与管道流动中的相似。它们表明，超大规模和主要湍流运动在雷诺切应力最大值上方的区域起到使流动减速的作用。
