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Effects of a Building's Density on Flow in Urban Areas
Jae-Jin KIM,Do-Yong KIM
Department of Environmental Atmospheric Sciences, Pukyong National University, Busan, Korea;Center for Atmosphere Science and Earthquake Research, Korea Meteorological Administration, Busan, Korea
Abstract The effects of a building's density on urban flows are investigated using a CFD model with the RNG k-ε turbulence closure scheme. Twenty-seven cases with different building's density parameters (e.g., building and street-canyon aspect ratios) are numerically simulated. As the building's density parameters vary, different flow regimes appear. When the street canyon is relatively narrow and high, two counter-rotating vortices in the vertical direction are generated. The wind speed along streets is mainly affected by the building's length. However, it is very difficult to find or generalize the characteristics of the street-canyon flows in terms of a single building's density parameter. This is because the complicated flow patterns appear due to the variation of the vortex structure and vortex number. Volume-averaged vorticity magnitude is a very good indicator to reflect the flow characteristics despite the strong dependency of flows on the variation of the building's density parameters. Multi-linear regression shows that the volume-averaged vorticity magnitude is a strong function of the building's length and the street-canyon width. The increase in the building's length decreases the vorticity of the street-canyon flow, while, the increase in the street-canyon width increases the vorticity.
Jae-Jin KIM,Do-Yong KIM, 2009: Effects of a Building's Density on Flow in Urban Areas . Adv. Atmos. Sci., 26(1), 45-56, doi: 10.1007/s00376-009-0045-9.
