Flow and Pollutant Dispersion Model in a 2D Urban Street Canyons Using Computational Fluid Dynamics

Document Type : Original Article

Author

Ph.D., Research Assistant, Heat Island Group, Building, Civil and Environmental Engineering Department, Concordia University, Montreal, Quebec, Canada

Abstract

A two-dimensional model is used to simulate temperature distribution, wind speed and pollutants dispersion within an isolated two-dimensional street canyon using SIMPLE algorithm in ANSYS Fluent version 16.2. The simulation is based on the Reynolds-averaged Navier–Stokes equations coupled with a series of standard, RNG and realizable k-ε turbulence models. Simulation domain consisted of a street canyon with two buildings enclosing a street with the aspect ratio of 1. The wind is assumed to be perpendicular to the direction of the street and the source of the pollution is assumed to be liner. The results showed that the RNG k-ε turbulence model is the most optimum model by comparing with the calculated data under different wind speed patterns and pollutant dispersion model. The improvement of turbulent viscosity term of the RNG k-ε turbulence model provides a more accurate and reliable numerical solution for the present study regarding to the pollution dispersion in a street canyon. The simulation results also showed that the dimensionless pollutant concentrations, P, is larger on the leeward side of the buildings and decrease exponentially from floor to top of the upstream buildings. Furthermore, the results showed that the pollutant concentrations on the leeward side of building are more than that on the windward side due to the pollutant transportation of vortex circulation.

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References

[1]       Fernando HJS, Lee SM, Anderson J, Princevac M, Pardyjak E, Grossman-Clarke S. Urban fluid mechanics: air circulation and contaminant dispersion in cities. Environ Fluid Mech 2001;1:107–64. doi:10.1023/A:1011504001479.
[2]       Britter RE, Hanna SR. Flow and dispersion in urban areas. Annu Rev Fluid Mech 2003;35:469–96.
[3]       Belcher SE. Mixing and transport in urban areas. Philos Trans R Soc A Math Phys Eng Sci 2005;363:2947–68. doi:10.1098/rsta.2005.1673.
[4]       Oke TR. Street design and urban canopy layer climate. Energy Build 1988;11:103–13. doi:https://doi.org/10.1016/0378-7788(88)90026-6.
[5]       Vardoulakis S, Fisher BEA, Pericleous K, Gonzalez-Flesca N. Modelling air quality in street canyons: a review. Atmos Environ 2003;37:155–82. doi:https://doi.org/10.1016/S1352-2310(02)00857-9.
[6]       Ahmad K, Khare M, Chaudhry KK. Wind tunnel simulation studies on dispersion at urban street canyons and intersections—a review. J Wind Eng Ind Aerodyn 2005;93:697–717. doi:https://doi.org/10.1016/j.jweia.2005.04.002.
[7]       Li X-X, Liu C-H, Leung DYC, Lam KM. Recent progress in CFD modelling of wind field and pollutant transport in street canyons. Atmos Environ 2006;40:5640–58. doi:https://doi.org/10.1016/j.atmosenv.2006.04.055.
[8]       Sini J-F, Anquetin S, Mestayer PG. Pollutant dispersion and thermal effects in urban street canyons. Atmos Environ 1996;30:2659–77. doi:https://doi.org/10.1016/1352-2310(95)00321-5.
[9]       Jandaghian Z, Touchaei AG, Akbari H. Sensitivity analysis of physical parameterizations in WRF for urban climate simulations and heat island mitigation in Montreal. Urban Clim 2017. doi:https://doi.org/10.1016/j.uclim.2017.10.004.
[10]     Jandaghian Z, Akbari H. The Effect of Increasing Surface Albedo on Urban Climate and Air Quality: A Detailed Study for Sacramento, Houston, and Chicago. Climate 2018;6:19. doi:10.3390/cli6020019.
[11]     Meroney RN, Pavageau M, Rafailidis S, Schatzmann M. Study of line source characteristics for 2-D physical modelling of pollutant dispersion in street canyons. J Wind Eng Ind Aerodyn 1996;62:37–56. doi:https://doi.org/10.1016/S0167-6105(96)00057-8.
[12]     Kastner-Klein P, Berkowicz R, Britter R. The influence of street architecture on flow and dispersion in street canyons. Meteorol Atmos Phys 2004;87. doi:10.1007/s00703-003-0065-4.
[13]     Kastner-Klein P, Rotach MW. Mean Flow and Turbulence Characteristics in an Urban Roughness Sublayer. Boundary-Layer Meteorol 2004;111:55–84. doi:10.1023/B:BOUN.0000010994.32240.b1.
[14]     Ca VT, Asaeda T, Ito M, Armfield S. Characteristics of wind field in a street canyon. J Wind Eng Ind Aerodyn 1995;57:63–80. doi:https://doi.org/10.1016/0167-6105(94)00117-V.
[15]     Uehara K, Murakami S, Oikawa S, Wakamatsu S. Wind tunnel experiments on how thermal stratification affects flow in and above urban street canyons. Atmos Environ 2000;34:1553–62. doi:https://doi.org/10.1016/S1352-2310(99)00410-0.
[16]     Kim J-J, Baik J-J. Urban street-canyon flows with bottom heating. Atmos Environ 2001;35:3395–404. doi:https://doi.org/10.1016/S1352-2310(01)00135-2.
[17]     Kim J-J, Baik J-J. Effects of inflow turbulence intensity on flow and pollutant dispersion in an urban street canyon. J Wind Eng Ind Aerodyn 2003;91:309–29. doi:https://doi.org/10.1016/S0167-6105(02)00395-1.
[18]     Xie X, Liu C-H, Leung DYC, Leung MKH. Characteristics of air exchange in a street canyon with ground heating. Atmos Environ 2006;40:6396–409. doi:https://doi.org/10.1016/j.atmosenv.2006.05.050.
[19]     Cheng H, Castro IP. Near Wall Flow over Urban-like Roughness. Boundary-Layer Meteorol 2002;104:229–59. doi:10.1023/A:1016060103448.
[20]     Coceal O, Thomas TG, Castro IP, Belcher SE. Mean Flow and Turbulence Statistics Over Groups of Urban-like Cubical Obstacles. Boundary-Layer Meteorol 2006;121:491–519. doi:10.1007/s10546-006-9076-2.
[21]     Hamlyn D, Hilderman T, Britter R. A simple network approach to modelling dispersion among large groups of obstacles. Atmos Environ 2007;41:5848–62. doi:https://doi.org/10.1016/j.atmosenv.2007.03.047.
[22]     Blocken B, Stathopoulos T, Saathoff P, Wang X. Numerical evaluation of pollutant dispersion in the built environment: Comparisons between models and experiments. J Wind Eng Ind Aerodyn 2008;96:1817–31. doi:https://doi.org/10.1016/j.jweia.2008.02.049.
[23]     Reynolds RT, Castro IP. Measurements in an urban-type boundary layer. Exp Fluids 2008;45:141–56. doi:10.1007/s00348-008-0470-z.
[24]     Buccolieri R, Sandberg M, Di Sabatino S. City breathability and its link to pollutant concentration distribution within urban-like geometries. Atmos Environ 2010;44:1894–903. doi:https://doi.org/10.1016/j.atmosenv.2010.02.022.
[25]     Kang Y-S, Baik J-J, Kim J-J. Further studies of flow and reactive pollutant dispersion in a street canyon with bottom heating. Atmos Environ 2008;42:4964–75. doi:https://doi.org/10.1016/j.atmosenv.2008.02.013.
[26]     Yakhot V, Orszag SA. Renormalization group analysis of turbulence. I. Basic theory. J Sci Comput 1986;1:3–51. doi:10.1007/BF01061452.
[27]     Shih T-H, Liou WW, Shabbir A, Yang Z, Zhu J. A new k-ϵ eddy viscosity model for high reynolds number turbulent flows. Comput Fluids 1995;24:227–38. doi:https://doi.org/10.1016/0045-7930(94)00032-T.
[28]     Chan TL, Dong G, Leung CW, Cheung CS, Hung WT. Validation of a two-dimensional pollutant dispersion model in an isolated street canyon. Atmos Environ 2002;36:861–72. doi:https://doi.org/10.1016/S1352-2310(01)00490-3.
[29]     Pielke RA, Cotton WR, Walko RL, Tremback CJ, Lyons WA, Grasso LD, et al. A comprehensive meteorological modeling system?RAMS. Meteorol Atmos Phys 1992;49:69–91. doi:10.1007/BF01025401.
[30]     ANSYS Fluent V16.2. User Guide n.d.
[31]     Li X-X, Britter RE, Norford LK, Koh T-Y, Entekhabi D. Flow and Pollutant Transport in Urban Street Canyons of Different Aspect Ratios with Ground Heating: Large-Eddy Simulation. Boundary-Layer Meteorol 2012;142:289–304. doi:10.1007/s10546-011-9670-9.
[32]     Li X-X, Britter RE, Koh TY, Norford LK, Liu C-H, Entekhabi D, et al. Large-Eddy Simulation of Flow and Pollutant Transport in Urban Street Canyons with Ground Heating. Boundary-Layer Meteorol 2010;137:187–204. doi:10.1007/s10546-010-9534-8.
Computational Engineering and Physical Modeling
Volume 1, Issue 1 - Serial Number 1
January 2018
Pages 83-93

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History

  • Receive Date: 13 March 2018
  • Revise Date: 09 April 2018
  • Accept Date: 09 April 2018

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