摘要
机动车尾气是城市大气污染物主要来源之一,其排放集中在城市街谷内靠近地面的空间,行驶车辆诱导的空气流动及湍流是影响街谷内空气流动与污染物扩散的重要因素。该文基于大涡模拟的湍流模型,用拉格朗日方法跟踪城市街谷内的行驶车辆,模拟行驶车辆影响下城市街谷内流场的演化过程,分析街谷内瞬时流场变化及行驶车辆诱导空气流动及湍流的产生机理。模拟结果表明:连续的行驶车流能够在其车道上方靠近地面的空间引起与车辆行驶方向相同的相对稳定的风场;街谷横截面上的瞬时流场中存在局部子涡,局部子涡形成在行驶车辆车身周围,携带车辆引起空气扰动的能量,并将其携带的能量传递给周边空气。行驶车辆以局部子涡的形式向周边空气传递的能力主要影响街谷内的空气湍流,也是行驶车辆影响街谷内空气湍流的主要方式。因此参数化模式的发展中应该重点考虑反映车辆诱导湍流的空间分布特征。
Moving vehicles have considerable effects both on pollutant emission and dispersion within urban street canyons. A Lagrangian method is adopted to track the movement of vehicles and the large eddy simulation method is used to simulate the moving vehicle induced air flows within urban street canyons. The evolution of the wind filed and the generation mechanism of vehicle induced turbulence in urban street canyons are investigated. Moving vehicles could induce steady air flows in the near ground areas above the traffic lanes. The instantaneous air flow fields within the street canyon indicate that the moving vehicles induced local eddies within the street canyon play a key role in carrying the moving vehicles motivated kinetic energy, and then releasing the kinetic energy continuously to the local air flows. The spatial distribution should be essentially considered in the development of parameterized vehicle induced turbulence models.
出处
《环境科学与技术》
CAS
CSCD
北大核心
2015年第9期64-69,136,共7页
Environmental Science & Technology
基金
科技支撑计划课题(2012BAJ15B06)
中央高校基本科研业务费专项项目:城市冠层内空气污染的物理机制及控制策略研究(xjj2014054)
关键词
城市街谷
大涡模拟
行驶车辆
拉格朗日模型
湍流
urban street canyon： large eddy simulation moving vehicle
Lagrangian scheme
turbulence
