基於透空式建築型態的街谷細懸浮微粒汙染物擴散數值模擬

Abstract

受發展影響都市空間結構呈現高層且高密度趨勢，頻繁的人為活動加上在密集空間裡持續排放汙染物，破壞都市微氣候環境造成負面效應(任超，2016；歐陽嶠暉，2005)，為改善惡化的都市環境，主要透過規劃與設計針對建物與街道空間型態進行優化，其中高密度的建築群影響周邊風環境，不利於街谷內汙染物的擴散，而透過透空式建築設計能減少建築迎風面面積，增加風通透性以改善都市環境 (香港屋宇署，2013)，過往研究多透過觀測的方式分析汙染物與氣象條件的關係，近期則針對汙染物進行電腦數值模擬，但採用顆粒物的模擬相對較少，因此本研究配合Hang, J. & Li, Y. G.(2010)理想城市10×9配置，設定透空式建築量體為長(30m)、寬(30m)、高(80m)，並以無透空建築為對照組，加上不同建築洞口高度(0.45h、0.65h及0.45-0.65h)為變項設計共4組研究方案，使用ANSYS Fluent v18進行風環境與PM2.5細懸浮微粒汙染物模擬。研究結果顯示:高層建築量體增加街道封閉性，導致空氣流通與汙染物擴散的阻礙，透空式建築能提高街道的滲透性改善空氣流通。隨著 Z 軸高度增加汙染物分佈受街谷空間及汙染源距離影響，因此較低的洞口具有較佳汙染物去除效果。連續且過長的街道讓汙染物累積於都市末端，建議維持足夠的都市空間讓街區空氣流通，以得到理想改善效果。  This study is based on opening buildings of length (30m), width (30m), and height (80m) combined with Hang, J. & Li, Y. G.(2010) ideal city 10 × 9 configurations, and building without hole is control group, different building opening heights (0.45h, 0.65h, and 0.45-0.65h) are designed as various groups of 4 research scenario. Using ANSYS Fluent v18 to simulate the wind environment and PM2.5 fine particulate matter. The results of the study found that the volume of high-rise buildings increased the sealing of the streets, leading to the obstruction of air circulation and the spread of pollutants. The opening buildings can increase the permeability of the streets and improve the air circulation. As the height of the Z-axis increases, the distribution of pollutants is affected by the space of the street canyon and the distance of the pollution source, so the lower hole has a better effect of removing pollutants. Continuous and long streets allow pollutants to accumulate at the end of the city. It is recommended to maintain sufficient urban space to allow air circulation in the blocks to obtain the desired improvement effect.