Effects of twisted wind flows on wind conditions in passages between buildings

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

doi:10.1016/j.jweia.2017.04.011

Cited by 49 publications

(28 citation statements)

References 13 publications

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“…These maximum K values of the wind flows at test point 71 may be attributed to the intense backflow generated by the high-rise buildings when the buildings are exposed to winds that approach from directions 180°to 200°. Then the variation of φ Kmax (i.e., the wind direction of the maximum K value) may be related to the modifications of upstream flow features by the twisted winds as discussed by Tse et al [20]. The second peak in K value, which is marginally less than 0.3, is found at 0°, for which the location of test point 71 is downstream of the group of high-rise buildings.…”

Section: Wind Conditions Around a Group Of High-rise Buildingsmentioning

confidence: 80%

“…In other words, there were four types of vanes employed to simulate twisted wind profiles in this study. The previous publications of the authors [18][19][20] provide more details of the vane system.…”

Section: Simulation Of Twisted Wind Profilesmentioning

confidence: 99%

“…The vertical variation in wind directions is a topic that has been insensitively studied in the field of yacht sail's aerodynamic [15][16][17]. Conversely, directional variations in a wind flow have not been systematically investigated in the field of wind engineering until very recent when Tse et al [18][19][20] conducted a series of wind tunnel tests using twisted wind profiles. Tse et al [18] first simulated twisted wind profiles, which have varying wind directions along the profile's height, in a BLWT and then used them for the wind tunnel tests to show the ways that twisted wind flows modify the PLW field near isolated buildings and arrays of buildings [19,20].…”

Section: Introductionmentioning

confidence: 99%

“…Conversely, directional variations in a wind flow have not been systematically investigated in the field of wind engineering until very recent when Tse et al [18][19][20] conducted a series of wind tunnel tests using twisted wind profiles. Tse et al [18] first simulated twisted wind profiles, which have varying wind directions along the profile's height, in a BLWT and then used them for the wind tunnel tests to show the ways that twisted wind flows modify the PLW field near isolated buildings and arrays of buildings [19,20]. Although these wind tunnel tests are indicative of the impact of twisted winds on the PLW field near https://doi.org/10.1016/j.buildenv.2017.11.041 Received 25 September 2017; Received in revised form 27 November 2017; Accepted 27 November 2017 generic buildings, it is not yet fully understood whether twisted wind profiles have similar importance in assessing the PLW field in an urban area.…”

Section: Introductionmentioning

confidence: 99%

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

Weerasuriya

Tse

Zhang

et al. 2018

Building and Environment

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The influence of twisted wind flows on the pedestrian-level wind (PLW) field of an urban area was evaluated by testing a typical urban site (Tsuen Wan, Hong Kong) in a boundary layer wind tunnel. Four twisted wind profiles with different magnitudes and directions of yaw angles were employed to investigate variations in wind speed with the properties of the twisted wind flows at the pedestrian level. An additional conventional wind profile with similar wind speeds and turbulence intensities to the twisted winds but with zero yaw angles was simulated for comparisons. The mean wind speeds at 77 locations including the perimeter, roadsides, and groups of highrise buildings were analysed for the conventional and the four twisted wind flows. The comparisons show a tendency of twisted winds to generate higher wind speeds at the pedestrian level than the conventional wind profile. The wind speeds of the twisted winds have a strong dependence on the magnitude and direction of the yaw angles, particularly at locations where the densities of buildings in the neighbourhood are low and hence local wind circulations are significantly modified by the twisted winds.

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Section: Wind Conditions Around a Group Of High-rise Buildingsmentioning

confidence: 80%

Section: Simulation Of Twisted Wind Profilesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

Weerasuriya

Tse

Zhang

et al. 2018

Building and Environment

Self Cite

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show abstract

“…Given that most urban areas in Hong Kong are located near mountains, and yaw angles have been observed to reach as much as 40°, Tse et al [11] proposed to employ twisted wind profiles in wind tunnel tests when the urban PLW field of Hong Kong is concerned. To follow up on this, Tse et al [15,16] conducted a series of wind tunnel tests to investigate the PLW fields around isolated buildings and arrays of buildings with different dimensions. Their results [15] revealed noticeable flow modifications in the PLW field under the influence of twisted wind flows.…”

Section: Introductionmentioning

confidence: 99%

New inflow boundary conditions for modeling twisted wind profiles in CFD simulation for evaluating the pedestrian-level wind field near an isolated building

Weerasuriya

Zhang

et al. 2018

Building and Environment

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The hilly topography of Hong Kong influences oncoming winds and gradually changes their wind directions along the profiles' height. The vertical variation in wind directions, or the twist effect, significantly influences the Pedestrian Level Wind (PLW) field in urban areas of Hong Kong, thus it is a topic demanding systematic investigations. In this study, a new set of inflow boundary conditions are proposed to model twisted wind flows in Computational Fluid Dynamic (CFD) simulations. The new inflow boundary condition derived based on the horizontal homogeneous assumption, specifies a vertical profile of lateral wind speeds at the inlet boundary to sustain the twist effect in the empty computational domain. The proposed boundary conditions are used to simulate the PLW fields near three isolated buildings with different Height-to-Width ratio using two CFD codes; OpenFOAM, and FLUENT. The results reveal that OpenFOAM is more reliable in simulating PLW fields in twisted wind flows using the new set of boundary conditions. The three-dimensional flow field provided by the OpenFOAM simulation shows sparse streamlines downstream the buildings, indicating lack of organized eddies in the building far wake, which negatively affects the dispersion of air pollutants in twisted winds.

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Correction of direction reduction factors of extreme wind speed considering the Ekman spiral in the wind load estimation of super high‐rise buildings with heights of 400–800 m

Quan

et al. 2023

Structural Design Tall Build

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Summary The wind direction in the atmospheric boundary layer (ABL) twists with height due to the Coriolis force; this phenomenon is called the Ekman spiral. However, this phenomenon is generally not considered in the present wind load estimation of super high‐rise buildings, which may lead to an incorrect estimation and affect the safety of structures. Therefore, this study considers and analyzes the influence of the Ekman spiral phenomenon in the wind direction reduction effect (WDRE) of the wind load of super high‐rise buildings. First, this paper proposes an empirical fitting equation for the twisted wind direction angle for a height of 100–800 m according to the classical Ekman spiral theory model (CE model). Subsequently, on the basis of twisted wind, this paper proposes a method for the correction of the wind direction reduction factors (WDRFs) of strong winds considering the influence of the Ekman spiral phenomenon in the design wind load estimation of super high‐rise buildings with heights of 400–800 m. A high‐frequency balance force measurement test of a square‐section super high‐rise building model was performed to analyze the influence of the Ekman spiral phenomenon on the WDRE of the aerodynamic force and wind‐induced response. Three Chinese cities (i.e., Beijing, Wuhan, and Kunming) are selected as case studies to illustrate the importance and necessity of the correction method. The results demonstrate that the proposed empirical fitting equation accurately determines the twisted wind direction angle at different latitudes and altitudes. Furthermore, estimating the design wind load while considering the WDRE and neglecting the influence of the Ekman spiral phenomenon may lead to a significant underestimation of the wind load of super high‐rise buildings, rendering the designed building structure more dangerous.

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Effects of twisted wind flows on wind conditions in passages between buildings

Cited by 49 publications

References 13 publications

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

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

New inflow boundary conditions for modeling twisted wind profiles in CFD simulation for evaluating the pedestrian-level wind field near an isolated building

Correction of direction reduction factors of extreme wind speed considering the Ekman spiral in the wind load estimation of super high‐rise buildings with heights of 400–800 m

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