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http://dx.doi.org/10.14191/Atmos.2015.25.4.659

A Study on Sensitivity of Pollutant Dispersion to Inflow Wind Speed and Turbulent Schmidt Number in a Street Canyon  

Wang, Jang-Woon (Department of Environmental Atmospheric Sciences, Pukyong National University)
Kim, Jae-Jin (Department of Environmental Atmospheric Sciences, Pukyong National University)
Publication Information
Atmosphere / v.25, no.4, 2015 , pp. 659-667 More about this Journal
Abstract
In this study, sensitivity of inflow wind speed and turbulent Schmidt number to pollutant dispersion in an urban street canyon is investigated, by comparing CFD-simulated results to wind-tunnel results. For this, we changed systematically inflow wind speed at the street-canyon height ($1.5{\sim}10.0m\;s^{-1}$ with the increment of $0.5m\;s^{-1}$) and turbulent Schmidt number (0.2~1.3 with interval of 0.1). Also, we performed numerical experiments under the conditions that turbulent Schmidt numbers selected with the magnitude of mean kinetic energy at each grid point were assigned in the street canyon. With the increase of the inflow wind speed, the model underestimated (overestimated) pollutant concentration in the upwind (downwind) side of the street canyon because of the increase of pollutant advection. This implies that, for more realistic reproduction of pollutant dispersion in urban street canyons, large (small) turbulent Schmidt number should be assigned for week (strong) inflow condition. In the cases of selectively assigned turbulent Schmidt number, mean bias remarkably decreased (maximum 60%) compared to the cases of constant turbulent Schmidt number assigned. At week (strong) inflow wind speed, root mean square error decreases as the area where turbulent Schmidt number is selectively assigned becomes large (small).
Keywords
CFD model; pollutant concentration; wind speed; turbulent Schmidt number; street canyon;
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Times Cited By KSCI : 3  (Citation Analysis)
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1 Kim, J.-J., and J.-J. Baik, 2003: Effects of inflow turbulence intensity on flow and pollutant dispersion in an urban street canyon. J. Wind Engineering Industrial Aerodyn., 53, 309-329.
2 Kim, J.-J., and J.-J. Baik, 2004: A numerical study of the effects of ambient wind direction on flow and dispersion in urban street canyons using the RNG k-${\varepsilon}$ turbulence model. Atmos. Environ., 38, 3039-3048.   DOI
3 Kim, J.-J., and J.-J. Baik, 2005: Classification of Flow Regimes in Urban Street Canyons Using a CFD Model. J. Korean Soc. Atmos. Environ., 21, 525-535.
4 Koeltzsch, K., 2000: The height dependence of the turbulent Schmidt number within the boundary layer. Atmos. Environ., 34, 1147-1151.   DOI
5 Lee, Y.-S., and J.-J. Kim, 2011: Effects of an Apartment on Flow and Dispersion in an Urban Area. Atmos. Korean Meteor. Soc., 21, 95-108.
6 Li, Y., and T. Stathopoulos, 1997: Numerical evaluation of wind-induced dispersion of pollutants around a building. J. Wind Engineering Industrial Aerodyn., 67&68, 757-766.
7 Lien, F.-S., E. Yee, H. Ji, A. Keats, and K.-J. Hsieh, 2006: Progress and challenges in the development of physically-based numerical models for prediction of flow and contaminant dispersion in the urban environment. Int. J. Computational Fluid Dyn., 20, 323-337.
8 Park, S.-J., D.-Y. Kim, and J.-J. Kim, 2013: Effects of Atmospheric Stability and Surface Temperature on Microscale Local Airflow in a Hydrological Suburban Area. Atmos. Korean Meteor. Soc., 23, 13-21.
9 Park, S.-J., and J.-J. Kim, 2014: Effects of Building-roof Cooling on Scalar Dispersion in Urban Street Canyons. Atmos. Korean Meteor. Soc., 24, 331-341.
10 Baik, J.-J., J.-J. Kim, and H.-J.-S. Fernando, 2003: A CFD Model for Simulating Urban Flow and Dispersion. J. Appl. Meteorol., 42, 1636-1648.   DOI
11 Baik, J.-J., Y.-S. Kang, and J.-J. Kim, 2007: Modeling reactive pollutant dispersion in an urban street canyon. Atmos. Environ., 41, 934-949.   DOI
12 Brzoska, M.-A., D. Stock, and B. Lamb, 1997: Determination of plume capture by the building wake. J. Wind Engineering Industrial Aerodyn., 67&68, 909-922.
13 Castro, I.-P., and D.-D. Apsley, 1997: Flow and dispersion over topography: a comparison between numerical and laboratory data for two dimensional flow. Atmos. Environ., 31, 839-850.   DOI
14 Flesch, T.-K., J.-H. Prueger, and J.-L. Hatfield, 2002: Turbulent Schmidt number from a tracer experiment. Agric. Forest Meteor., 111, 299-307.   DOI
15 He, G., Y. Guo, and A.-T. Hsu, 1999: The effect of Schmidt number on turbulent scalar mixing in a jet-in-cross flow. Int. J. Heat and Mass Transfer, 42, 3727-3738.   DOI
16 Huang, H., J. Imran, A.-M. ASCE, and C. Pirmez, 2005: Numerical Model of Turbidity Currents with a Deforming Bottom Boundary. J. Hydrauric Engineering, 131, 283-293.   DOI
17 Riddle, A., D. Carruthers, A. Sharpe, C. McHugh, and J. Stocker, 2004: Comparisons between FLUENT and ADMS for atmospheric dispersion modelling. Atmos. Environ., 38, 1029-1038.   DOI
18 Park, S.-J., J.-J. Kim., M.-J. Kim, R.-J. Park, and H.-B. Cheong, 2015: Characteristics of flow and reactive pollutant dispersion in urban street canyons. Atmos. Environ., 108, 20-31.   DOI
19 Patankar, S.-V., 1980: Numerical Heat Transfer and Fluid Flow.
20 Pavageau, M., and M. Schatzmann, 1999: Wind tunnel measurements of concentration fluctuations in an urban street canyon. Atmos. Environ., 33, 3961-3971.   DOI
21 Tang, W., A. Huber, B. Bell, and W. Schwarz, 2006: Application of CFD simulations for short-range atmospheric dispersion over open fields and within arrays of building. AMS 14th Joint Conference on the Applications of Air Pollution Meteorology with the A&WMA, Atlanta GA, J1.8.
22 Tominaga, Y., and T. Stathopoulos, 2007: Turbulent Schmidt numbers for CFD analysis with various types of flowfield. Atmos. Environ., 41, 8091-8099.   DOI
23 Versteeg, H. K., and W. Malalasekera, 1995: An Introduction to Computational Fluid Dynamics: The Finite Volume Method. Longman, Malaysia, 257 pp.
24 Wang, X., 2006: Numerical Simulation of Wind Induced Dispersion of Emissions From Rooftop Stacks. M.A.Sc. Thesis, Concordia University, Montreal, Quebec, Canada.
25 Wang, X., and K.-F. Mcnamara, 2006: Evaluation of CFD Simulation using RANS Turbulence Models for Building Effects on Pollutant Dispersion. Environ. Fluid Mech., 6, 181-202.   DOI
26 Zhang, Y.-Q., S.-P. Arya, and W.-H. Snyder, 1996: A Comparison of Numerical and Physical Modeling of Stable Atmospheric Flow and Dispersion around a Cubical Building. Atmos. Environ., 30, 1327-1345.   DOI
27 Wang, X., T. Stathopoulos, and P. Saathoff, 2006: Numerical evaluation of dispersion of pollutants in the building environment: comparisons with models and experiments. The Fourth International Symposium on Computational Wind Engineering, Yokohama, Japan., 805-808.
28 Yakhot, V., S.-A. Orszag, S. Thangam, T.-B. Gatski, and C.-G. Speziale, 1992: Development of turbulence models for shear flows by a double expansion technique. Phys. Fluids A, 4, 1510-1520.   DOI
29 Yimer, I., I. Campbell, and L.-Y. Jiang, 2002: Estimation of the turbulent Schmidt number from experimental profiles of axial velocity and concentration for High-Reynolds-Number Jet Flows. Can. Aeronautics Space J., 48, 195-200.   DOI