Large-Eddy Simulation of the Effects ofWind-Direction Fluctuations on Turbulent Flow and Gas Dispersion Within a Cubical Canopy
Large-Eddy Simulation of the Effects ofWind-Direction Fluctuations on Turbulent Flow and Gas Dispersion Within a Cubical Canopy
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风向脉动对立方体冠层内湍流和气体扩散影响的大涡模拟
DOI：
10.1007/s10546-019-00467-y
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发表时间：
2019
影响因子：
4.3
通讯作者：
Ayumu SATO
中科院分区：
文献类型：
--
作者：
Takenobu MICHIOKA;Hiroshi TAKIMOTO;Hiroki Ono;Ayumu SATO
采用大涡模拟方法对立方体冠层内的湍流和气体扩散进行了数值模拟，研究了风向波动对气体扩散的影响。方块以规则的间隔设置在底面上，线源放置在第一、第二、第三、第五和第七行内。无风向波动的大涡模拟得到了风洞实验得到的平均流向速度分量，以及流向和跨向速度分量涨落的标准差。风向波动对第一排冠层以上的平均流向速度分量影响不大，对第三排以上的分量影响不大。冠层以上流向和跨向速度分量的波动的标准差也受风向波动的影响，但在冠层内这两个分量对第三排以上的波动不太敏感。在第三排之前有风向波动的峡谷内的空间平均浓度略大于没有波动的浓度，但在第五排之后基本上是相同的。通过峡谷的低频湍流是在有和没有风向波动的情况下产生的。
Large-eddy simulation of turbulent flow and gas dispersion in a cubical canopy is used to investigate the effect of wind-direction fluctuations on gas dispersion. Square blocks are set at regular intervals on the bottom surface, with line sources placed within the first, second, third, fifth and seventh rows. Large-eddy simulation without wind-direction fluctuations produces a good prediction of the mean streamwise velocity component, and the standard deviations of the fluctuations in the streamwise and spanwise velocity components, obtained from a wind-tunnel experiment. Wind-direction fluctuations marginally affect the mean streamwise velocity component above the canopy in the first row, and do not significantly affect the component beyond the third row. The standard deviations of the fluctuations in the streamwise and spanwise velocity components above the canopy are also affected by wind-direction fluctuations, but within the canopy the components are less sensitive to the fluctuations beyond the third row. The spatially-averaged concentrations within the canyon with wind-direction fluctuations before the third row are marginally greater than concentrations without the fluctuations, but they are essentially identical beyond the fifth row. The low-frequency turbulent flow that passes through the canyon is generated with and without wind-direction fluctuations.