Mean Wind Flow Field around Idealized Block Arrays with Various Aspect Ratios

Abstract:

This study investigates the characteristic of spatially averaged mean velocity profile and the flow pattern within urban canopy layer especially in pedestrian level using CFD technique. Large eddies simulation (LES) was used to perform a series of simulation of the flow around block arrays with staggered arrangement under various conditions of aspect ratio, α_p (roof-to-frontal area ratio) from 0.33 to 3.0. The spatially-average profiles of both mean wind speed and streamwise velocity over various block arrays were compared with each other. The analysis clarified the following two facts. 1) The vertical mean flow structure inside the canyon change due to change a plan area ratio and block aspect ratio. 2) The horizontal mean flow structure around the block change if pedestrian level change form z = 0.05h to z = 0.25h. This can be translated to the effect of high-rise building to the flow around the building.

• Periodical: Applied Mechanics and Materials (Volume 393)
• Pages: 767-773
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.393.767
• Online since: September 2013
• Authors: Azli Abd Razak, Aya Hagishima, Naoki Ikegaya, Mohd Faizal Mohamad, Sheikh Ahmad Zaki
• Keywords: Block Aspect Ratio, Flow Pattern, LES, Pedestrian Wind Environment, Vortex

References

[1] T. R. Oke, Street design and urban canopy layer climate, Energy and Building. 11 (1988) 103 – 113.

DOI: 10.1016/0378-7788(88)90026-6

[2] L. J. Hunter, I. D. Watson and G. T. Johnson, Modelling air flow regimes in urban canyons, Energy and Building. 15 - 16 (1991) 315 – 324.

DOI: 10.1016/0378-7788(90)90004-3

[3] J. F. Sini, S. Anquetin and P. G. Mestayer, Pollutant dispersion and thermal effects in urban street canyons, Atmospheric Environment. 30 (1996) 2659 – 2677.

DOI: 10.1016/1352-2310(95)00321-5

[4] J. J. Baik and J. J. Kim, A numerical study of flow and pollutant dispersion characteristics in urban street canyons, J. Appl. Meteorol. 38 (1999) 1576 – 1589.

DOI: 10.1175/1520-0450(1999)038<1576:ansofa>2.0.co;2

[5] R. Martinuzzi and C. Tropea, The flow around surface-mounted, prismatic obstacles placed in a fully developed channel flow, J. Fluids Engineering. 115 (1993) 85 – 92.

DOI: 10.1115/1.2910118

[6] E. R. Meinders and . K. Hanjalić, Vortex structure and heat transfer in turbulent flow over a wall-mounted matrix of cubes, Int. J. Heat and Fluid Flow. 20 (1999) 255 – 267.

DOI: 10.1016/s0142-727x(99)00016-8

[7] O. Coceal, . T. G. Thomas , . I. P. Castro and S. E. Belcher, Mean flow and turbulence statistics over groups of urban-like cubical obstacles, Boundary-Layer Meteorol. 121 (2006) 491 – 519.

DOI: 10.1007/s10546-006-9076-2

[8] M. O. Letzel, High resolution large-eddy simulation of turbulent flow around building, PhD Thesis (2007).

[9] S. Raasch and M. Schröter, PALM – A large-eddy simulation model performing on massively parallel computers, Meteorologische Zeitschrift. 10 (2001) 363 – 372.

DOI: 10.1127/0941-2948/2001/0010-0363

[10] A. Abd Razak, A. Hagishima, N. Ikegaya and J. Tanimoto, Analysis of airflow over building arrays for assessment of urban wind environment, Building and Environment. 59 (2013) 56 – 65.

DOI: 10.1016/j.buildenv.2012.08.007

[11] Y. Yang and Y. Shao, Numerical simulations of flow and pollutioan dispersion in urban atmospheric boundary layer, Environmental Modelling & Software. 23 (2008) 906 – 921.

DOI: 10.1016/j.envsoft.2007.10.005

[12] I. N. Harman, J. F. Barlow and S. E. Belcher, Scalar fluxes from urban street canyons. Part II: Model, Bondary-Layer Meteorol. 131 (2004) 387 – 360.

DOI: 10.1007/s10546-004-6205-7

[13] O. Coceal and S. E. Belcher, Mean flow and turbulence statistics over groups of urban-like cubical obstacles, Boundary-Layer Meteorol. 121 (2005) 491 – 519.

DOI: 10.1007/s10546-006-9076-2

[14] T. Kubota, . M. Miura, . Y. Tominaga and A. Mochida, Wind tunnel tests on the relationship between building density and pedestrian-level wind velocity: Development of guidelines for realizing acceptable wind environment in residential neighborhoods, Building and Environment. 43 (2008).

DOI: 10.1016/j.buildenv.2007.10.015