지붕 표면 열 플럭스가 난류 고유 구조 및 오염물질 분산에 미치는 효과에 대한 큰 에디 모의

• Published in: 한국대기환경학회지, 41(2) pp. 343 - 359
• Main Authors: 한범순, 김동휘, 박경주, 홍성호, 백종진
• Format: Journal Article
• Language: Korean
• Published: 한국대기환경학회 01.04.2025
• Subjects: 대기과학
• ISSN: 1598-7132; 2383-5346
• DOI: 10.5572/KOSAE.2025.41.2.343

Turbulent coherent structures over urban surfaces are known to play important roles in turbulent momentum and heat transfers. However, their associations with pollutant dispersion are less known, especially when urban surfaces are heated or cooled. This study examines the effects of roof surface heat flux on turbulent coherent structures and pollutant dispersion in and above a cubical building array using the PArallelized Large-eddy simulation Model (PALM). Three simulations with roof surface heat fluxes of 0 (neutral), 0.1 (heating), and -0.1 K m s-1 (cooling) are conducted. The turbulent coherent structures in the heating and neutral simulations well develop in the horizontal and vertical directions, exhibiting large correlations between the pedestrian level and roof level and between the roof level and above. On the other hand, in the cooling simulation, the sizes of turbulent coherent structures are small compared to those in the heating and neutral simulations and turbulent coherent structures exhibit no correlations between the roof level and above. To examine the effects of roof surface heat flux on turbulent momentum, pollutant, and heat fluxes, quadrant analysis is performed at the roof level. In all three simulations, the ejection and sweep events most frequently occur and they are accompanied by pollutant ejection and pollutant sweep events, respectively. The frequency of warm updraft (cold updraft) events is lowest in the heating (cooling) simulation, being associated with marginal changes in potential temperature with height below the roof level. To further examine the effects of roof surface heat flux on turbulent flow and pollutant dispersion during strong ejection and sweep events, flushing events and cavity eddy events are identified. During both flushing and cavity eddy events, vertical turbulent pollutant exchanges are accompanied by stronger (weaker) vertical turbulent flows in the heating (cooling) simulation than in the neutral simulation. KCI Citation Count: 0