TY - JOUR

T1 - A new semi-empirical model for estimating the drag coefficient of the vertical random staggered arrays using LES

AU - Mohammad, Ahmad Faiz

AU - Zaki, Sheikh Ahmad

AU - Ikegaya, Naoki

AU - Hagishima, Aya

AU - Ali, Mohamed Sukri Mat

N1 - Funding Information:
This research was financially supported by the grant project of ASEAN University Network/Southeast Asia Engineering Education Development Network (AUN/SEED-Net) (Vot 4B229 ) under the Japan International Cooperation Agency (JICA) and the Research University Grant ( 17H94 ) project of Universiti Teknologi Malaysia .
Publisher Copyright:
© 2018 Elsevier Ltd

PY - 2018/9

Y1 - 2018/9

N2 - Sheltering of buildings has a significant impact on the total drag of an urban surface. This study performs large eddy simulations (LESs) of flows over vertical random arrays (comprised of buildings with height variability) in staggered layout to estimate the drag coefficient, CD. The vertical random arrays are configured in several frontal area densities, λF (ratio of buildings’ frontal area to total surface area) ranging from 0.09 to 0.81. The sheltering effect is parameterized using the individual building's wind pressure coefficient, Cp(t) normalized with that of the isolated building, Cp(iso). The ratio Cp(t)/Cp(iso) is well correlated with the target building's frontal area density, λf(t). Subsequently, the relationship between Cp(t) and λf(t) is expressed using power law equations for three building categories based on the height-to-width ratio, αp(t): tall (2.64 ≤ αp(t) ≤ 3.76), medium-rise (1.32 ≤ αp(t) ≤ 2.00), and low-rise (0.36 ≤ αp(t) ≤ 0.84). Based on the Cp(t), an equation of the CD is formulated, yielding the following outcomes. Firstly, the predicted CD values are mostly within 10% of the previous experimental results. Secondly, a semi-empirical model is derived, whereby the predicted CD values are generally consistent for various vertical random arrays.

AB - Sheltering of buildings has a significant impact on the total drag of an urban surface. This study performs large eddy simulations (LESs) of flows over vertical random arrays (comprised of buildings with height variability) in staggered layout to estimate the drag coefficient, CD. The vertical random arrays are configured in several frontal area densities, λF (ratio of buildings’ frontal area to total surface area) ranging from 0.09 to 0.81. The sheltering effect is parameterized using the individual building's wind pressure coefficient, Cp(t) normalized with that of the isolated building, Cp(iso). The ratio Cp(t)/Cp(iso) is well correlated with the target building's frontal area density, λf(t). Subsequently, the relationship between Cp(t) and λf(t) is expressed using power law equations for three building categories based on the height-to-width ratio, αp(t): tall (2.64 ≤ αp(t) ≤ 3.76), medium-rise (1.32 ≤ αp(t) ≤ 2.00), and low-rise (0.36 ≤ αp(t) ≤ 0.84). Based on the Cp(t), an equation of the CD is formulated, yielding the following outcomes. Firstly, the predicted CD values are mostly within 10% of the previous experimental results. Secondly, a semi-empirical model is derived, whereby the predicted CD values are generally consistent for various vertical random arrays.

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U2 - 10.1016/j.jweia.2018.08.003

DO - 10.1016/j.jweia.2018.08.003

M3 - Article

AN - SCOPUS:85053070757

VL - 180

SP - 191

EP - 200

JO - Journal of Industrial Aerodynamics

JF - Journal of Industrial Aerodynamics

SN - 0167-6105

ER -