Petersen Ron L, Guerra Sergio A, Bova Anthony S
a CPP, Inc ., Fort Collins , CO , USA.
J Air Waste Manag Assoc. 2017 Aug;67(8):826-835. doi: 10.1080/10962247.2017.1279088. Epub 2017 Jan 12.
The only documentation on the building downwash algorithm in AERMOD (American Meteorological Society/U.S. Environmental Protection Agency Regulatory Model), referred to as PRIME (Plume Rise Model Enhancements), is found in the 2000 A&WMA journal article by Schulman, Strimaitis and Scire. Recent field and wind tunnel studies have shown that AERMOD can overpredict concentrations by factors of 2 to 8 for certain building configurations. While a wind tunnel equivalent building dimension study (EBD) can be conducted to approximately correct the overprediction bias, past field and wind tunnel studies indicate that there are notable flaws in the PRIME building downwash theory. A detailed review of the theory supported by CFD (Computational Fluid Dynamics) and wind tunnel simulations of flow over simple rectangular buildings revealed the following serious theoretical flaws: enhanced turbulence in the building wake starting at the wrong longitudinal location; constant enhanced turbulence extending up to the wake height; constant initial enhanced turbulence in the building wake (does not vary with roughness or stability); discontinuities in the streamline calculations; and no method to account for streamlined or porous structures.
This paper documents theoretical and other problems in PRIME along with CFD simulations and wind tunnel observations that support these findings. Although AERMOD/PRIME may provide accurate and unbiased estimates (within a factor of 2) for some building configurations, a major review and update is needed so that accurate estimates can be obtained for other building configurations where significant overpredictions or underpredictions are common due to downwash effects. This will ensure that regulatory evaluations subject to dispersion modeling requirements can be based on an accurate model. Thus, it is imperative that the downwash theory in PRIME is corrected to improve model performance and ensure that the model better represents reality.
美国气象学会/美国环境保护局监管模型AERMOD中关于建筑物尾流算法的唯一文档，即所谓的PRIME（烟羽抬升模型增强版），见于舒尔曼、斯特里迈蒂斯和西雷2000年发表在《美国大气与环境学会会刊》上的文章。近期的现场和风洞研究表明，对于某些建筑物配置，AERMOD可能会将浓度预测高估2至8倍。虽然可以进行风洞等效建筑物尺寸研究（EBD）来大致校正这种高估偏差，但过去的现场和风洞研究表明，PRIME建筑物尾流理论存在明显缺陷。通过计算流体动力学（CFD）以及对简单矩形建筑物上的气流进行风洞模拟对该理论进行的详细审查揭示了以下严重的理论缺陷：建筑物尾流中的湍流增强从错误的纵向位置开始；恒定的增强湍流一直延伸到尾流高度；建筑物尾流中初始增强湍流恒定（不随粗糙度或稳定性变化）；流线计算中的不连续性；以及没有考虑流线型或多孔结构的方法。
本文记录了PRIME中的理论及其他问题，以及支持这些发现的CFD模拟和风洞观测结果。虽然AERMOD/PRIME对于某些建筑物配置可能提供准确且无偏差的估计（误差在2倍以内），但需要进行重大审查和更新，以便对于因尾流效应而常见显著高估或低估的其他建筑物配置能够获得准确估计。这将确保受扩散模型要求约束的监管评估能够基于准确的模型。因此，必须校正PRIME中的尾流理论以提高模型性能，并确保该模型能更好地反映实际情况。
