Roughness sublayer flows over real urban morphology: A wind tunnel study

Mo, Ziwei; Ho, Yat-Kiu

doi:10.1016/j.buildenv.2020.107463

Cited by 28 publications

(5 citation statements)

References 61 publications

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“…Fifty measurement points were randomly selected in the study area and their CFD simulation results were compared with the wind tunnel test results (Figure 7). The root mean square error (RMSE) of the wind speed ratio between the CFD simulation and the wind tunnel test was found to be 0.02, which is close to the RMSE value of 0.08∼0.24 found in similar validation studies [87], indicating the credibility of the CFD results. Additional information on the wind tunnel test, CFD approach, model set-up and validation can be found in the Supplementary Material (see Supplementary Material: Note S1).…”

Section: Eer Reviewsupporting

confidence: 77%

A Novel Quantitative Approach to the Spatial Configuration of Urban Streets Based on Local Wind Environment

Ji,

Li,

et al. 2023

Land

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The urban street is an important part of the urban form and serves as the primary medium for public activities within cities. The morphological characteristics of urban street space not only influence people’s spatial experience but also have an impact on the quality of the physical environment, such as the wind environment. Numerous scholars have studied the wind environment of streets with different morphological characteristics using abstract and simplified street models, uncovering certain relationships between specific morphological features and airflow patterns. However, due to the significant disparity between simplified models and reality, researchers have attempted to develop models applicable to the complex characteristics of urban street space, with the aim of exploring the relationship between street spatial features and airflow characteristics. This study explores a method to quantify the complex spatial characteristics of urban streets, using a series of parameters to describe the streets, such as average width, proportion of secondary interfaces, and proportion of opening length. Streets with different spatial characteristics in the centre of Nanjing are selected and quantified. A comparison is conducted between the parameters representing street spatial morphology and the simulation results of the wind environment in the area, aiming to assess the effectiveness of these parameter values. The results demonstrate that complex urban spaces can still be effectively represented through parameterization and confirm the validity of our quantitative representation of complex street spatial characteristics. The results could serve as a reference for urban design and urban construction.

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Section: Eer Reviewsupporting

confidence: 77%

A Novel Quantitative Approach to the Spatial Configuration of Urban Streets Based on Local Wind Environment

Ji,

Li,

et al. 2023

Land

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“…(2021); Mo et al. (2021) and therefore not easily accessible by the public. Furthermore, urban geometries were simulated with varying resolutions and differed in how the non‐building urban features were treated, making direct comparisons and reproduction of their results difficult.…”

Section: Methodsmentioning

confidence: 99%

Novel Geometric Parameters for Assessing Flow Over Realistic Versus Idealized Urban Arrays

Nazarian

Hart

et al. 2023

J Adv Model Earth Syst

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Urban heterogeneity, such as the variation of street layouts, building shapes, and building heights, cannot be fully represented by density parameters commonly used in idealized urban environmental analyses. To address this shortcoming and better model flow fields over complex urban neighborhoods, we propose two novel descriptive geometric parameters, alignedness and building facet entropy, which quantify the connectivity of inter‐building spaces along the prevailing wind direction and the variation of building facet orientations, respectively. We then conducted large eddy simulations over 101 urban layouts, including realistic urban configurations with uniform building height as well as idealized building arrays with variable heights, and evaluated the resulting bulk flow properties. Urban canopy flow over realistic neighborhoods resembles staggered building arrays for low urban densities but becomes similar to aligned configurations beyond λp ∼ 0.25 where the realistic flow is less sensitive to changes in density. We further show that compared to traditional density parameters (such as plan and frontal area densities), the mean alignedness, a measure of connectivity of flow paths in street canyons, better predicts canopy‐averaged flow properties. Furthermore, for realistic urban flow, the dispersive momentum flux shows a clear increasing trend with building density, and a decreasing trend with alignedness, which is in contrast with idealized cases that exhibit no clear trend. This distinct behavior further highlights the necessity of evaluating flow over realistic urban layouts for flow parameterization. This study provides an improved method of describing urban layouts for flow characterization that can be applied in neighborhood‐scale urban canopy parameterization.

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“…However, each of the assumptions has its drawbacks. For applications in urban context especially at the nearground level, the log-law wind profile's validity is dubious, as the roughness of urban areas would significantly alter the atmospheric boundary layer's (ABL) layered structure which makes the log-law wind profile less accurate [1,2]. The power-law wind profile is an empirical assumption that describes the ground surface roughness's influence on the wind profile, of which the validity in describing the near-ground wind profile is also dubious.…”

Section: Introductionmentioning

confidence: 99%

Mean Wind Velocity Distribution at Near-ground Level Obtained Through Field Measurements

Zhong

Liu²,

Liang³

2022

E3S Web Conf.

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Mean wind velocity profiles enable researchers to conduct efficient and accurate analyses of a wide variety of urban microclimatic problems, such as pollution dispersion, heat island effect and pedestrian wind comfort. However, due to the heterogeneity in the complex urban context, the wind profile at near-ground level within the real urban context remains insufficiently investigated. The present study aims to measure the near-ground level mean wind profiles in an industrial park. To this practical end, a sonic anemometer was equipped to a height adjustable bar on a mobile measurement platform. Through adjusting the sonic anemometer’s height, the mean wind velocities at different heights of the near-ground level were measured. Results indicate that the mean wind velocities’ variation along the near-ground heights measured at the site exposed to open and flat upwind areas can be reasonably captured by the power-law profile, while the other two conventional profiles, i.e. the log-law and the exponential profiles, show different levels of inaccuracy.

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Roughness sublayer flows over real urban morphology: A wind tunnel study

Cited by 28 publications

References 61 publications

A Novel Quantitative Approach to the Spatial Configuration of Urban Streets Based on Local Wind Environment

A Novel Quantitative Approach to the Spatial Configuration of Urban Streets Based on Local Wind Environment

Novel Geometric Parameters for Assessing Flow Over Realistic Versus Idealized Urban Arrays

Mean Wind Velocity Distribution at Near-ground Level Obtained Through Field Measurements

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