Venkatram Akula, Heist David K, Perry Steven G, Brouwer Lydia
University of California at Riverside, Riverside, CA, USA.
US Environmental Protection Agency, Research Triangle Park, NC, USA.
Atmos Pollut Res. 2021 Feb 5;12(2):367-374. doi: 10.1016/j.apr.2020.11.017.
This paper presents an analysis of data from a wind tunnel study conducted to examine the dispersion of emissions at the edges of near-road noise barriers. The study is motivated by the concern that a barrier positioned downwind of a roadway may guide highly polluted plumes along the barrier leading to heightened concentrations as the plume spills around and downwind of the barrier end. The wind tunnel database consists of measurements of dispersion around a simulated roadway segment with various noise barrier configurations. Each roadway segment simulated in the wind tunnel had full-scale equivalent dimensions of 135 m long. Barrier segments, 135 m long with a height () of 6 m, were located on the downwind side of the source at a distance of 18 m from it (measured perpendicularly from the line source). Examination of the concentration patterns associated with the cases indicates that 1) vertical mixing induced by barriers persists at crosswind distances up to the edge (lateral end) of the barrier and downwind distances of = 10, 2) concentration levels at all heights below = 1 increase towards the edge of the barrier at downwind distances less than = 7, and 3) concentration is well mixed in the vertical at the edge of the barrier, and the levels can be higher than in the middle of the barrier even when the source ends at the edge of the barrier. We have formulated a parameterization that captures the major features of these observations and can be incorporated in models such as RLINE.
本文对一项风洞研究的数据进行了分析，该研究旨在考察近路隔音屏障边缘处排放物的扩散情况。开展这项研究的动机在于，人们担心位于道路下风侧的屏障可能会引导高污染羽流沿着屏障流动，导致当羽流在屏障末端周围和下风侧溢出时浓度升高。风洞数据库包含了在具有各种隔音屏障配置的模拟道路路段周围进行的扩散测量数据。风洞中模拟的每个道路路段的全尺寸等效长度为135米。高度（）为6米、长度为135米的屏障段位于源的下风侧，距离源18米（从线源垂直测量）。对与这些情况相关的浓度模式的研究表明：1）屏障引起的垂直混合在横风距离直至屏障边缘（横向末端）以及下风距离 = 10处仍然存在；2）在小于 = 7的下风距离处，低于 = 1的所有高度处的浓度水平朝着屏障边缘增加；3）在屏障边缘处，浓度在垂直方向上充分混合，并且即使源在屏障边缘处结束，此处的浓度水平也可能高于屏障中间位置的浓度水平。我们已经制定了一种参数化方法，该方法捕捉了这些观测结果的主要特征，并且可以纳入诸如RLINE等模型中。
