Vortex generation in oscillatory canopy flow
Vortex generation in oscillatory canopy flow
复制标题
DOI：
10.1002/jgrc.20073
复制
发表时间：
2013-03
影响因子：
--
通讯作者：
M. Ghisalberti;Tamara L. Schlosser
中科院分区：
文献类型：
--
作者：
M. Ghisalberti;Tamara L. Schlosser
在本文中，我们首次证明了在振荡(即波控)流动中，冠层顶部会产生相干涡旋。通过一系列流动显示实验表明，当满足由Keulegan-Carpenter(Kc)数和Reynolds(Re)数描述的两个条件时，旋涡就会形成。首先，波动周期必须足够长，以允许在树冠顶部产生剪切驱动的不稳定；这在KC≳5时发生。第二，涡旋不稳定必须能够克服粘性的稳定效应；这在Re≳1000时发生。涡旋极大地增加了树冠内垂直混合的速度，因此任何对海岸树冠停留时间的预测都需要了解是否正在发生涡流。
[1] In this paper, we demonstrate for the first time the generation of coherent vortices at the top of a canopy in oscillatory (i.e., wave-dominated) flow. Through a series of flow visualization experiments, vortex formation is shown to occur when two conditions described by the Keulegan–Carpenter (KC) and Reynolds (Re) numbers are met. First, the wave period must be sufficiently long to allow the generation of the shear-driven instability at the top of the canopy; this occurs when KC ≳ 5. Second, the vortex instability must be able to overcome the stabilizing effects of viscosity; this occurs when Re ≳ 1000. The vortices greatly increase the rate of vertical mixing within the canopy, such that any prediction of residence time in a coastal canopy requires an understanding of whether vortex generation is occurring.