包括在城市环境中用于单列分散模型的分散剪切应力
Jonathan Retter1,2, David Heist2, Michael Pirhalla3
1ORAU ORISE Research Participation Program Hosted at EPA, Research Triangle Park, NC, USA.
概括
这项研究揭示了将分散应力纳入摩擦速度计算的方法对城市地区空气污染分散模型产生了重大影响. 包括这些压力可以改善预测,特别是在建筑物附近,通过考虑复杂的风力模式.
科学领域:
- 环境科学环境科学
- 大气科学 大气科学
- 计算流体动力学 计算流体动力学
背景情况:
- 高斯分散模型在摩擦速度计算中经常忽略分散应力.
- 这种监督限制了像AERMOD这样的模型在复杂的城市环境中的准确性.
- 精确的摩擦速度对于参数化污染物分散至关重要.
研究的目的:
- 调查包括分散应力在摩擦速度计算中的影响.
- 将这些新计算与城市分散模型中的现有方法进行比较.
- 评估在理想的城市环境中对预测的污染物度的影响.
主要方法:
- 使用风洞验证的中性分层大型模拟 (LES).
- 模拟理想化的均和不均的城市区域,不同的风角 (0°,10°,30°,50°).
- 使用雷诺兹和分散应力组成部分在城市树冠上方计算摩擦速度.
主要成果:
- 不统一的城市模型显示,在大多数街区和流动角度都有显著的分散应力.
- 一个简单的功率定律表达式准确地预测了城市摩擦速度在9.6%以内.
- 包括分散剪切应力在内增加了第一行预测的污染物度 (+20.6%至+21.2%),但在其他地方产生了轻微影响.
结论:
- 在城市分散模型中,分散应力对于准确的摩擦速度估计至关重要.
- 现有的AERMOD方法与LES结果的一致性较差.
- 未来的高斯模型应该包含分散应力,以改善城市空气质量预测.
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