The impact of roadside trees on traffic released PM10 in urban street canyon: Aerodynamic and deposition effects
The impact of roadside trees on traffic released PM10 in urban street canyon: Aerodynamic and deposition effects
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DOI：
10.1016/j.scs.2017.02.001
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发表时间：
2017-04-01
影响因子：
11.7
通讯作者：
Li, Xiaofeng
中科院分区：
文献类型：
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作者：
Xue, Fei;Li, Xiaofeng
植树有可能通过空气动力学和沉积效应影响当地的空气质量。然而，以往的研究大多没有考虑到沉积效应，这可能会导致对污染水平的高估。本文研究了路边树木对街道峡谷空气质量的空气动力学和沉积效应，并利用CFD方法评估了这些影响对不同树木参数的敏感性。研究了理想隔离街道峡谷中交通释放PM10的扩散特性。结果表明，在气动效应方面，压力损失系数是影响近壁面平均浓度的主要因素，背风面和迎风面分别高达+54%和-39%。叶面积密度和沉降速度是影响沉降效果的主要因素。与相同压力损失系数的情况相比，大叶面积密度和高沉积速度的情况下，背风面沉积效果可达-39%，迎风面沉积效果可达-89%，而低沉积速度的情况下，沉积效果不明显。综上所述，空气动力效应和沉积效应可能是影响街道峡谷空气质量的主要因素，在评估街道峡谷污染水平时应谨慎处理植被参数。(C) 2017 Elsevier Ltd.版权所有。
Tree planting has the potential to affect local air quality by both aerodynamic and deposition effects. However, most of the previous studies have failed to take deposition effect into account, which may lead to overestimation in pollution level. This study evaluates the aerodynamic and deposition effects of roadside trees on street canyon air quality and assesses the sensitivity of these effects to different tree parameters by CFD approach. The dispersion of traffic released PM10 in an idealized isolated street canyon are investigated. The results show that, for aerodynamic effect, pressure loss coefficient is a major factor on near -wall mean concentrations, up to +54% and -39% at leeward and windward, respectively. For deposition effect, leaf area density and deposition velocity are dominant factors. When compared with cases having the same pressure loss coefficient, the deposition effect of cases with large leaf area density and high deposition velocity reaches as much as -39% at leeward and -89% at windward, while for low deposition velocity, deposition effect is not distinguishable. Overall, the results suggest that both aerodynamic and deposition effects could be major impacts in street canyon air quality, and that vegetation parameters should be carefully handled when assessing street canyon pollution level. (C) 2017 Elsevier Ltd. All rights reserved.