TY - JOUR
T1 - Large-eddy simulation of turbulent flow in a densely built-up urban area
AU - Park, Seung Bu
AU - Baik, Jong Jin
AU - Han, Beom Soon
N1 - Publisher Copyright:
© 2013, Springer Science+Business Media Dordrecht.
PY - 2015/4
Y1 - 2015/4
N2 - Turbulent flow in a densely built-up area of Seoul, South Korea, is numerically investigated using the parallelized large-eddy simulation model. Based on the analysis of streamwise velocity and column-averaged vertical turbulent momentum flux, three areas of interest are selected: a downstream area of an apartment complex, an area behind high-rise buildings, and a park area. In the downstream area of the apartment complex, a large wake develops and a region of strong vertical turbulent momentum flux appears above the wake. At the height of maximum vertical turbulent momentum flux magnitude, all the four quadrant events occur in larger magnitude and contribute more to the vertical turbulent momentum transport than the averages in the main domain. In the area behind the high-rise buildings, fluctuating wakes and vortices are distinct flow structures around the top of the tallest building and updrafts induced by the flow structures appear as strong ejections just behind the high-rise buildings or farther downstream. While strong ejections are dominant at building-top heights, downdrafts along the windward walls of high-rise buildings are distinct below building-top heights and they induce high turbulent kinetic energy and winding flow around the high-rise buildings near the ground surface, transporting momentum downward and intermittently into nearby streets. In the park area located downstream in the main domain, turbulent eddies exist well above the ground surface, and the thickness of the interfacial region between low-speed air and high-speed air increases and complex turbulent flow appears in the interfacial region.
AB - Turbulent flow in a densely built-up area of Seoul, South Korea, is numerically investigated using the parallelized large-eddy simulation model. Based on the analysis of streamwise velocity and column-averaged vertical turbulent momentum flux, three areas of interest are selected: a downstream area of an apartment complex, an area behind high-rise buildings, and a park area. In the downstream area of the apartment complex, a large wake develops and a region of strong vertical turbulent momentum flux appears above the wake. At the height of maximum vertical turbulent momentum flux magnitude, all the four quadrant events occur in larger magnitude and contribute more to the vertical turbulent momentum transport than the averages in the main domain. In the area behind the high-rise buildings, fluctuating wakes and vortices are distinct flow structures around the top of the tallest building and updrafts induced by the flow structures appear as strong ejections just behind the high-rise buildings or farther downstream. While strong ejections are dominant at building-top heights, downdrafts along the windward walls of high-rise buildings are distinct below building-top heights and they induce high turbulent kinetic energy and winding flow around the high-rise buildings near the ground surface, transporting momentum downward and intermittently into nearby streets. In the park area located downstream in the main domain, turbulent eddies exist well above the ground surface, and the thickness of the interfacial region between low-speed air and high-speed air increases and complex turbulent flow appears in the interfacial region.
KW - Densely built-up urban area
KW - Ejection
KW - Large-eddy simulation
KW - Sweep
KW - Turbulence coherent structure
KW - Turbulent flow
KW - Wake
UR - http://www.scopus.com/inward/record.url?scp=84882756602&partnerID=8YFLogxK
U2 - 10.1007/s10652-013-9306-3
DO - 10.1007/s10652-013-9306-3
M3 - Article
AN - SCOPUS:84882756602
SN - 1567-7419
VL - 15
SP - 235
EP - 250
JO - Environmental Fluid Mechanics
JF - Environmental Fluid Mechanics
IS - 2
ER -