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Aerodynamic Parameters of Urban Building Arrays with Random Geometries

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It is difficult to describe the flow characteristics within and above urban canopies using only geometrical parameters such as plan area index (λ p ) and frontal area index (λ f ) because urban surfaces comprise buildings with random layouts, shapes, and heights. Furthermore, two types of ‘randomness’ are associated with the geometry of building arrays: the randomness of element heights (vertical) and that of the rotation angles of each block (horizontal). In this study, wind-tunnel experiments were conducted on seven types of urban building arrays with various roughness packing densities to measure the bulk drag coefficient (C d ) and mean wind profile; aerodynamic parameters such as roughness length (z o ) and displacement height (d) were also estimated. The results are compared with previous results from regular arrays having neither ‘vertical’ nor ‘horizontal’ randomness. In vertical random arrays, the plot of C d and z o versus λ f exhibited a monotonic increase, and z o increased by a factor of almost two for λ f = 48–70%. C d was strongly influenced by the standard deviation of the height of blocks (σ) when λ p ≥ 17%, whereas C d was independent of σ when λ p = 7%. In the case of horizontal random arrays, the plot of the estimated C d against λ f showed a peak. The effect of both vertical and horizontal randomness of the layout on aerodynamic parameters can be explained by the structure of the vortices around the blocks; the aspect ratio of the block is an appropriate index for the estimation of such features.

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  • Burian SJ, Brown MJ, Linger SP (2002) Morphological analyses using 3D building databases, Los Angeles, California. LA-UR-02-0781, Los Alamos National Laboratory, Los Alamos, 66 pp

  • Cheng H, Castro IP (2002a) Near wall flow over urban-like roughness. Boundary-Layer Meteorol 104: 229–259

    Article  Google Scholar 

  • Cheng H, Castro IP (2002b) Near-wall flow development after a step change in surface roughness. Boundary-Layer Meteorol 105: 411–432

    Article  Google Scholar 

  • Cheng H, Hayden P, Robins AG, Castro IP (2007) Flow over cube arrays of different packing densities. Boundary-Layer Meteorol 95: 715–740

    Google Scholar 

  • Coceal O, Thomas TG, Castro IP, Belcher SE (2006) Mean flow and turbulence statistics over groups of urban-like cubical obstacles. Boundary-Layer Meteorol 121: 491–519

    Article  Google Scholar 

  • Di Sabatino S, Solazzo E, Paradisi P, Britter R (2008) A simple model for spatially-averaged wind profiles within and above an urban canopy. Boundary-Layer Meteorol 127: 131–151

    Article  Google Scholar 

  • Grimmond CSB, OKE TR (1999) Aerodynamic properties of urban areas derived from analysis of surface form. J Appl Meteorol 38: 1262–1292

    Article  Google Scholar 

  • Hagishima A, Tanimoto J (2005) Investigations of urban surface conditions for urban canopy model. Build Environ 40: 1638–1650

    Article  Google Scholar 

  • Hagishima A, Tanimoto J, Nagayama K, Meno S (2009) Aerodynamic parameters of regular arrays of rectangular blocks with various geometries. Boundary-Layer Meteorol 132: 315–337

    Article  Google Scholar 

  • Hanna SR, Tehraniana S, Carissimoa B, Macdonald RW, Lohner R (2002) Comparisons of model simulations with observations of mean flow and turbulence within simple obstacle arrays. Atmos Environ 33: 5067–5079

    Article  Google Scholar 

  • Hansen AC, Cermak JE (1975) Vortex-containing wakes of surface obstacles. Project THEMIS Technical Report No. 29, Civil Engineering, Department Colorado State University ADA019785, 163 pp

  • Jackson PS (1981) On the displacement height in the logarithmic velocity profile. J Fluid Mech 111: 15–25

    Article  Google Scholar 

  • Jiang D, Jiang W, Liu H, Sun J (2008) Systematic influence of different building spacing, height and layout on mean wind and turbulent characteristics within and over urban building arrays. Wind Struct 11: 275–289

    Google Scholar 

  • Kanda M (2006) Large-eddy simulations on the effects of surface geometry of building arrays on turbulent organized structures. Boundary-Layer Meteorol 118: 151–168

    Article  Google Scholar 

  • Kanda M, Moriizumi T (2009) Momentum and heat transfer over urban-likes surfaces. Boundary-Layer Meteorol 131: 385–401

    Article  Google Scholar 

  • Kanda M, Moriwaki R, Kasamatsu F (2004) Large eddy simulation of turbulent organized structure within and above explicitly resolved cube arrays. Boundary-Layer Meteorol 112: 343–368

    Article  Google Scholar 

  • Macdonald RW, Griffiths RF, Hall DJ (1998) An improved method for estimation of surface roughness of obstacle arrays. Atmos Environ 32: 1857–1864

    Article  Google Scholar 

  • Perry AE, Schofield WH, Joubert PN (1969) Rough wall turbulent boundary layers. J Fluid Mech 37: 383–413

    Article  Google Scholar 

  • Plate, EJ (eds) (1982) Engineering meteorology: studies in wind engineering and industrial aerodynamics, vol 1. Elsevier, Amsterdam, p 740

    Google Scholar 

  • Raupach MR, Hughes DE, Cleugh HA (2006) Momentum absorption in rough-wall boundary layers with sparse roughness elements in random and clustered distributions. Boundary-Layer Meteorol 120: 201–218

    Article  Google Scholar 

  • Santiago JL, Coceal O, Martilli A, Belcher SE (2008) Variation of the sectional drag coefficient of a group of buildings with packing density. Boundary-Layer Meteorol 128: 445–457

    Article  Google Scholar 

  • Snyder WH, Castro IP (2002) The critical Reynolds number for rough-wall boundary layers. J Wind Eng Ind Aerodyn 90: 41–54

    Article  Google Scholar 

  • Stoesser T, Mathey F, Frohlich J, Rodi W (2003) LES of flow over multiple cubes. Ercoftac Bull 56: 15–19

    Google Scholar 

  • Xie Z-T, Coceal O, Castro IP (2008) Large-eddy simulation of flows over random urban-like obstacles. Boundary-Layer Meteorol 129: 1–23

    Article  Google Scholar 

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Correspondence to Sheikh Ahmad Zaki.

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Zaki, S.A., Hagishima, A., Tanimoto, J. et al. Aerodynamic Parameters of Urban Building Arrays with Random Geometries. Boundary-Layer Meteorol 138, 99–120 (2011).

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