| Year of Publication | 2015 | Division | Applied Meteorology Research Division |
|---|---|---|---|
| Title | A Study on the Characteristics of Flow and Reactive Pollutants’ Dispersion in Step-up Street Canyons Using a CFD Model | ||
| Author | 김은령 | ||
| Coauthor | 박록진, 이대근 | ||
| ISBN(ISSN) | Name of Journal | 한국기상학회 대기지 | |
| Category (International/Domestic) | 국내 | Vol. No. | 25(3) |
| Research Project Title | 차세대 도시농림융합스마트기상서비스개발 (2015년) | Publication Date | 2015-09-01 |
| Keywords | Step-up street canyon, flow characteristics, reactive pollutants’ dispersion, CFD model, wind-tunnel experiment | ||
In this study, street canyons with a higher downwind building (so called, step-up street
canyons) are considered for understanding characteristics of flow and reactive pollutants’
dispersion as a basic step to understand the characteristics in wider urban areas.
This study used a CFD_NIMR_SNU coupled to a chemistry module just including simple
NOX-O₃ photochemical reactions. First, flow characteristics are analyzed in step-up
street canyons with four aspect ratios (0.33, 0.47, 0.6, 0.73) defined as ratios of upwind
building heights to downwind building height. The CFD_NIMR_SNU reproduced very
well the main features (that is, vortices in the street canyons) which appeared in the
wind-tunnel experiment. Wind speed within the street canyons became weak as the aspect
ratio increased, because volume of flow incoming over the upwind building decreased.
For each step-up street canyon, chemistry transport model was integrated up to 3600 s
with the time step of 0.5 s. The distribution patterns of NOX and O₃ were largely
dependent on the mean flow patterns, however, NOX and O₃ concentrations were
partly affected by photochemical reactions. O₃ concentration near the upwind lower
region of the street canyons was much lower than background concentration, because
there was much reduction in O₃ concentration due to NO titration there. Total amount
of NOX in the street canyons increased with the aspect ratio, resulting from the
decrease of mean wind intensity.
canyons) are considered for understanding characteristics of flow and reactive pollutants’
dispersion as a basic step to understand the characteristics in wider urban areas.
This study used a CFD_NIMR_SNU coupled to a chemistry module just including simple
NOX-O₃ photochemical reactions. First, flow characteristics are analyzed in step-up
street canyons with four aspect ratios (0.33, 0.47, 0.6, 0.73) defined as ratios of upwind
building heights to downwind building height. The CFD_NIMR_SNU reproduced very
well the main features (that is, vortices in the street canyons) which appeared in the
wind-tunnel experiment. Wind speed within the street canyons became weak as the aspect
ratio increased, because volume of flow incoming over the upwind building decreased.
For each step-up street canyon, chemistry transport model was integrated up to 3600 s
with the time step of 0.5 s. The distribution patterns of NOX and O₃ were largely
dependent on the mean flow patterns, however, NOX and O₃ concentrations were
partly affected by photochemical reactions. O₃ concentration near the upwind lower
region of the street canyons was much lower than background concentration, because
there was much reduction in O₃ concentration due to NO titration there. Total amount
of NOX in the street canyons increased with the aspect ratio, resulting from the
decrease of mean wind intensity.
