Abstract
We investigated the effects of wall- and tree-type fences on the airflow and fine particular matter (PM2.5) concentration around a school using a computational fluid dynamics (CFD) model. First, we validated the simulated wind speeds and PM2.5 concentrations against measured values, and the results satisfied the recommended criteria of the statistical validation indices used. Then, we evaluated the fence effects for 16 inflow directions by conducting numerical simulations with different fence types and heights. With east–southeasterly inflow, relatively high PM2.5 from the road was transported to the school. However, the wall-type fence prevented the PM2.5 from the road from entering the school, and the PM2.5 concentration decreased significantly downwind of the fence. With east–northeasterly inflow, the horizontal wind speed decreased due to the drag caused by the tree-type fence, resulting in a shift in the flow convergence region. The PM2.5 concentration decreased in the region of strengthened upward flow. This occurred because the number of pollutants transported from the background decreased. A comparison of the two fence types revealed that the effect of the tree-type fence on inbound pollutants was more significant, due to increased upward flows, than the effect of the wall-type fence.
Highlights
For the T2M case close to the realistic configuration, we validated the computational fluid dynamics (CFD) model against the wind directions and speeds measured by the 3D sonic anemometer and PM2.5 concentrations measured by the sensor network around the school [25]
The CFD model improved the prediction of wind speed and satisfied the normalized root mean square error (NRMSE), VG, MG, fractional biaserror (FB), and FAC2 criteria
We investigated the effects of wall- and tree-type fences on the airflows and PM2.5 concentrations in a school from an aerodynamics perspective using an RNG k-ε CFD model
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Many studies have shown that the outdoor air pollution associated with road emissions affects indoor air quality [4,5,6]. Investigations of outdoor air quality with road emissions and the relevant policies can contribute to improving indoor air quality. Fences and trees are the major objects that affect the airflow and air quality around roads [7,8], and the air quality in a school with fences and tree is affected by changes in airflow and pollutant dispersion. This study numerically investigated the effects of wall- and tree-type fences on airflow and PM2.5 concentration around a school, focusing on the outdoor air quality. We analyzed the effects of constructing fences and planting trees on airflow and PM2.5 concentration by running simulations with and without fences or trees for 16 inflow directions
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