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Environmental Fluid Mechanics

, Volume 15, Issue 2, pp 235–250 | Cite as

Large-eddy simulation of turbulent flow in a densely built-up urban area

  • Seung-Bu Park
  • Jong-Jin Baik
  • Beom-Soon Han
Original Article

Abstract

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.

Keywords

Turbulent flow Large-eddy simulation Ejection  Sweep Wake  Turbulence coherent structure Densely built-up urban area 

Notes

Acknowledgments

The authors thank two anonymous reviewers for providing valuable comments on this work. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea Ministry of Education, Science and Technology (MEST) (No. 2012-0005674) and also supported by the Brain Korea 21 Project (through the School of Earth and Environmental Sciences, Seoul National University).

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Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  1. 1.School of Earth and Environmental SciencesSeoul National UniversitySeoulSouth Korea

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