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

Abstract

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.

The Ventilation Efficiency of Urban Built Intensity and Ventilation Path Identification: A Case Study of Wuhan

“…Urban ventilation research has significance for urban planning [ 39 , 40 ]. Traditional urban planning lacks the aspect of climate research, which plays an important role in the realization of urban sustainable development and in solving urban environmental problems.…”

Urban Design with the Wind: Pedestrian-Level Wind Field in the Street Canyons Downstream of Parallel High-Rise Buildings

“…Since the 1960s, studies of pedestrian wind environments have attracted significant attention. Relevant studies were generally categorized into three aspects, one that examines the effects of a single high-rise building on its surrounding pedestrian-level wind field [1][2][3][4][5], another that investigates the effects of high-rise buildings [6][7][8][9][10][11][12][13][14] and another that focuses on urban street canyons [12][13][14][15][16][17].…”

“…This finding contradicts results obtained from previous studies on parallel street canyon passages. Li et al [12] validated the wind network index based on wind tunnel test results (spatial average velocity, surface pressure on individual buildings and total drag force). They found that the wind network index can effectively identify building layout effects on the wind field.…”

Three-Dimensional Wind Field Construction and Wind Turbine Siting in an Urban Environment

“…Many researchers focus on urban wind field construction and analysis. The straightforward methods are wind tunnel testing and field measurements [2][3][4][5]. Earlier wind tunnel tests were done by Wiren et al [2], where they conducted experimental studies of wind velocities in passages between and through block-type building models with various types of layouts.…”

“…More recently, Weerasuriya et al [4] conducted wind tunnel studies to uncover the effects of twisted wind flows on pedestrian-level wind fields in an urban environment. Finally, Li et al performed wind tunnel studies and tried to find the correlation between urban space quantification and pedestrian-level ventilation [5].…”