Effect of stable stratification on dispersion within urban street canyons: A large-eddy simulation
Name
Stable_stratification_paper_final.pdf
Description
Submitted version
Size
7.48 MB
Format
Adobe PDF
Checksum (MD5)
2ed2954efb35dfb920861f2cedf08758
Author(s)
Li, Xianxiang
Britter, Rex E
Norford, Leslie Keith
Date Issued
August 2016
Journal
Atmospheric Environment
Publisher
Elsevier BV
Citation
Li, Xianxiang, et al. "Effect of stable stratification on dispersion within urban street canyons: A large-eddy simulation." Atmospheric Environment 144 (November 2016): 47-59 © 2016 Elsevier Ltd
Version
Original manuscript
Abstract
This study employs a validated large-eddy simulation (LES) code with high tempo-spatial resolution to investigate the effect of a stably stratified roughness sublayer (RSL) on scalar transport within an urban street canyon. The major effect of stable stratification on the flow and turbulence inside the street canyon is that the flow slows down in both streamwise and vertical directions, a stagnant area near the street level emerges, and the vertical transport of momentum is weakened. Consequently, the transfer of heat between the street canyon and overlying atmosphere also gets weaker. The pollutant emitted from the street level ‘pools’ within the lower street canyon, and more pollutant accumulates within the street canyon with increasing stability. Under stable stratification, the dominant mechanism for pollutant transport within the street canyon has changed from ejections (flow carries high-concentration pollutant upward) to unorganized motions (flow carries high-concentration pollutant downward), which is responsible for the much lower dispersion efficiency under stable stratifications. Keywords: Large-eddy simulation (LES); Urban street canyon; Pollutant dispersion; Stable stratification
MIT Department
Singapore-MIT Alliance in Research and Technology (SMART)
Massachusetts Institute of Technology. Department of Urban Studies and Planning
Massachusetts Institute of Technology. Department of Architecture
Terms of Use
Creative Commons Attribution-NonCommercial-NoDerivs License
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1016/J.ATMOSENV.2016.08.069
