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Wind and Structures Volume 9, Number 4, July 2006 , pages 315-330 DOI: https://doi.org/10.12989/was.2006.9.4.315 |
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Modeling flow and scalar dispersion around Cheomseongdae |
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Jae-Jin Kim,Hyo-Jong Song and Jong-Jin Baik
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| Abstract | ||
| Flow and scalar dispersion around Cheomseongdae are numerically investigated using a three-dimensional computational fluid dynamics (CFD) model with the renormalization group (RNG) k - e turbulence closure scheme. Cheomseongdae is an ancient astronomical observatory in Gyeongju, Korea, and is chosen as a model obstacle because of its unique shape, that is, a cylinder-shaped architectural structure with its radius varying with height. An interesting feature found is a mid-height saddle point behind Cheomseongdae. Different obstacle shapes and corresponding flow convergences help to explain the presence of the saddle point. The predicted size of recirculation zone formed behind Cheomseongdae increases with increasing ambient wind speed and decreases with increasing ambient turbulence intensity. The relative roles of inertial and eddy forces in producing cavity flow zones around an obstacle are conceptually presented. An increase in inertial force promotes flow separation. Consequently, cavity flow zones around the obstacle expand and flow reattachment occurs farther downwind. An increase in eddy force weakens flow separation by mixing momentum there. This results in the contraction of cavity flow zones and flow reattachment occurs less far downwind. An increase in ambient wind speed lowers predicted scalar concentration. An increase in ambient turbulence intensity lowers predicted maximum scalar concentration and acts to distribute scalars evenly. | ||
| Key Words | ||
| computational fluid dynamics; renormalization group k-e turbulence model; Cheomseongdae; recirculation zone; saddle point; flow reattachment; scalar dispersion. | ||
| Address | ||
| Jae-Jin Kim; Climate Environment System Research Center, Seoul National University, Seoul 151-742, KorearnHyo-Jong Song and Jong-Jin Baik; School of Earth and Environmental Sciences, Seoul National University, Seoul 151-742, Korea | ||