A wind tunnel study of effects of twisted wind flows on the pedestrian-level wind field in an urban environment

Weerasuriya, Asiri Umenga; Tse, Kam Tim; Zhang, Xuelin; Li, S.W.

doi:10.1016/j.buildenv.2017.11.041

Cited by 43 publications

(20 citation statements)

References 35 publications

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“…Two twisted wind profiles and a conventional wind profile were employed as approaching wind profiles for the detailed AVA test. The two twisted wind profiles were simulated using a novel vane system originally developed by Tse et al [12] and were proven to be having consistent wind speeds and turbulence intensities to conduct successful pedestrian-level wind tunnel studies as reported previously [15][16][17]. Fig.…”

Section: The Wind Tunnel Experimentsmentioning

confidence: 99%

“…In addition, the hilly terrain of Hong Kong frequently produces twisted wind profiles: at different heights within the profile winds have various directions [12][13][14]. The authors of this paper have used twisted wind profiles in a series of wind tunnel tests on isolated buildings [16], arrays of buildings [16], and a real urban area [17], and have demonstrated the profiles' considerable influence on the PLW fields in built-up areas. This influence is even more critical on AVA as reported by Tse et al [12] after analysing data of 256 wind profiles obtained from 13 previous AVAs.…”

Section: Introductionmentioning

confidence: 98%

“…Although few studies attempted to improve the accuracy of AVA by addressing special environmental conditions such as unstable atmospheric stability [18,19], the existence of highly complex terrain [20], the presence of buildings with different heights [21], and heterogeneous urban morphology and surface roughness [22] but to the best of the authors' knowledge, no AVA has ever used twisted wind profiles as a boundary condition. This omission is partially attributable to inadequate understanding on simulation techniques, as only limited information has been made available by several studies on yacht sail's aerodynamics [23][24][25][26] and a few PLW studies done by the authors [15][16][17]. Constraints in cost, time, and resources pertaining to simulating twisted wind profiles give further reasons for omitting them from AVA.…”

Section: Introductionmentioning

confidence: 99%

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Integrating twisted wind profiles to Air Ventilation Assessment (AVA): The current status

Weerasuriya

Tse

Zhang

et al. 2018

Building and Environment

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Twisted wind flows generated by the complex terrain of Hong Kong induce two types of complication to Air Ventilation Assessment (AVA), first, imposing a false boundary condition on the wind tunnel tests done for AVA and, second, creating an ambiguity in determining the approaching wind direction in calculating the probability of occurrence of winds. The latter issue is partially solved using correction methods in post-analysis of AVA but the accuracy of these methods is not yet accessed. This study employs two twisted wind profiles to test an urban area in a boundary layer wind tunnel to investigate the influence of twisted wind flows on the outcomes of AVA and to estimate the accuracy of three common correction methods: No-Shift, Threshold, and Proportional methods. The results reveal significant differences in wind speeds at the pedestrian level for twisted and conventional wind flows at locations with low building densities. The discrepancies in wind speeds are minimum at the locations where the density of buildings is high. The indicators calculated by the No-Shift method frequently deviate from those of the twisted wind flows, while the Threshold and Proportional methods routinely overpredict the indicators of AVA.

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Section: The Wind Tunnel Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Integrating twisted wind profiles to Air Ventilation Assessment (AVA): The current status

Weerasuriya

Tse

Zhang

et al. 2018

Building and Environment

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“…Some researchers have utilized "around buildings" arrangements to study a wind environment around buildings [19,22,23] (Figure 1c). Some researchers have utilized "distributed" arrangements to perform the wind environment assessment for built-up areas [24,25] (Figure 1d). In the wind tunnel experiments, authors have used different arrangements of measurement points for different research objectives [18][19][20][21][22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

“…Some researchers have utilized "distributed" arrangements to perform the wind environment assessment for built-up areas [24,25] (Figure 1d). In the wind tunnel experiments, authors have used different arrangements of measurement points for different research objectives [18][19][20][21][22][23][24][25]. These four main arrangements of measurement points take into consideration some urban spatial characteristics (such as streets), but because their research purpose is not based on the characteristics of the urban space, the arrangements do not fully reflect the characteristics of the urban space.…”

Section: Introductionmentioning

confidence: 99%

A Wind Tunnel Study on the Correlation between Urban Space Quantification and Pedestrian–Level Ventilation

Peng

et al. 2019

Atmosphere

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Correlation research on urban space and pedestrian–level wind (PLW) environments is helpful for improving the wind comfort in complex urban space. It could also be significant for building and urban design. Correlation research is usually carried out in a space with clear urban spatial characteristics, so it is necessary to define the space first. In this paper, a typical urban area in Nanjing, China, is selected as the research object, and a spatial partition method is used to divide the real complex urban space into subspaces. The urban spatial characteristics of such subspaces are quantified using three urban spatial indices: openness (O), area (A), and shape (S). By comparing the quantitative results, 24 (12 pairs) subspaces with prominent urban spatial indices are selected as the correlation research cases. The 24 subspaces also provide a reference for the layout of the measurement points in a wind tunnel experiment. This is a new arrangement for locating the measurement points of a wind tunnel for correlation research. In the experiment, 45 measurement points are located, and the mean wind velocity of four different wind directions at 45 measurement points is experimented. The results clearly show that, when the experimental conditions are the same, the changes of mean wind velocity ratio (UR) of 24 (12pairs) subspaces under the four experimental wind directions are close. The URs of the subspaces are not significantly affected by the wind direction, which is affected more by the subspaces’ spatial characteristics. When making the correlation analysis between mean wind speed ratio and spatial characteristics’ indices, a direct numerical comparison was not able to find a correlation. By comparing the difference values of mean wind speed (△UR) and indices between each pair of subspaces, the correlation between UR and openness of subspaces were found. Limited by spatial partition method, the correlation between UR and the other indices was not obvious.

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Effect of aspect ratio on the aerodynamic performance and correlation of square section building exposed to twisted wind profile

Zhou,

Tse,

et al. 2023

Structural Design Tall Build

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SummaryThis study investigates the aerodynamic performance of three square‐section buildings with different aspect ratio (AR = 1:1, 1:4, and 1:6) exposed to twisted wind profile (TWP) by pressure measurement test. The effect of AR on the correlation of wind loads specifically for TWP is systematically revealed from both time–frequency domain and local–global perspective. Results show that compared with its counterparts in conventional wind profile (CWP), the effect of AR on aerodynamic load under TWP becomes significantly different and more prominent, which can be categorized into two types of patterns. For pattern low‐rise building, TWP is more resembling the condition of CWP with certain attack angle. For pattern high‐rise building, TWP results in stronger momentum exchange along building height but suppresses fluctuating feature associated with Karman vortex. As a result, under TWP, mean base moments of all buildings are enhanced except for longitudinal component of case AR = 1:4 and 1:6; while the fluctuating base moment for three AR cases is all reduced, which indicates that dynamic pattern of wake flow is suppressed. Moreover, the discrepancy of local wind load between case CWP and TWP concentrates on the lower‐middle location for high‐rise building but distributed evenly along all low‐rise building height. Additionally, it is found that the effect of AR on aerodynamic correlation exhibits different mechanisms and patterns when building is under the impact of CWP or TWP.

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A wind tunnel study of effects of twisted wind flows on the pedestrian-level wind field in an urban environment

Cited by 43 publications

References 35 publications

Integrating twisted wind profiles to Air Ventilation Assessment (AVA): The current status

Integrating twisted wind profiles to Air Ventilation Assessment (AVA): The current status

A Wind Tunnel Study on the Correlation between Urban Space Quantification and Pedestrian–Level Ventilation

Effect of aspect ratio on the aerodynamic performance and correlation of square section building exposed to twisted wind profile

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