An experimental study of flow through rigid vegetation
An experimental study of flow through rigid vegetation
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DOI：
10.1029/2008jf001042
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发表时间：
2008-12
影响因子：
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通讯作者：
D. Liu;P. Diplas;J. D. Fairbanks;C. Hodges
中科院分区：
文献类型：
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作者：
D. Liu;P. Diplas;J. D. Fairbanks;C. Hodges
[1]要更好地理解植被在流体和污染物运输中的作用，就需要提高对植被内部详细流动结构的认识。本研究不采用空间平均，而是在冠层内多个位置使用离散测量来开发速度和湍流强度剖面，并观察水通过刚性销子模拟的植被阵列时流动特性的变化。采用一维激光多普勒测速仪采集了水下和水面两种工况下的流速数据。还研究了销钉布置、密度和粗糙度的影响。结果表明：植被阵列内的速度随深度不变，其上的速度剖面呈对数关系，但边界上有拐点。最强的涡旋和湍流强度可以在那里找到，特别是在销钉的下游区域。这些结果支持了这样一种观点，即靠近床层和钉阵顶部的区域的流动非常不稳定，导致了相干结构的形成，并且是显著的质量和动量交换区域。
[1] Better understanding of the role of vegetation in the transport of fluid and pollutants requires improved knowledge of the detailed flow structure within the vegetation. Instead of spatial averaging, this study uses discrete measurements at multiple locations within the canopy to develop velocity and turbulence intensity profiles and observe the changes in the flow characteristics as water travels through a vegetation array simulated by rigid dowels. Velocity data was collected with a one dimensional laser Doppler velocimeter under emergent and submerged flow conditions. The effects of dowel arrangement, density, and roughness were also examined. The results show that the velocity within the vegetation array is constant with depth and the velocity profile is logarithmic above it, however the boundaries are marked by inflection points. The strongest vortices and turbulence intensities can be found there, especially in the region immediately downstream of a dowel. These results support the idea that the flow in the region near the bed and at the top of the dowel array is very unstable leading to the formation of coherent structures and are areas of significant mass and momentum exchange.