Wind tunnel measurement dataset of 3D turbulent flow around a group of generic buildings with and without a high-rise building

This paper presents a high tempo-spatial resolution dataset of the three-dimensional (3D) turbulent flow over a group of generic buildings with and without a high-rise building measured in an atmospheric boundary layer wind tunnel. This dataset is the basis of the study reported in the research article entitled “Wind tunnel measurement of three-dimensional turbulent flow structures around a building group: Impact of high-rise buildings on pedestrian wind environment” by Tominaga and Shirzadi (2021), which investigates the effect of a high-rise building on the pedestrian wind environment formed around the surrounding buildings and its interaction mechanism with the street flow at the pedestrian height. The instantaneous velocity vectors over a vertical central plane and a horizontal plane and the time-averaged surface pressure over the central building were measured for two cases consisting of a low-rise (Case 1H) and high-rise (Case 3H) buildings, which are in the center of a group of eight low-rise cubic buildings at a regular arrangement with an urban planar area density of 0.25. Data acquisition procedure and measurements details are explained in this paper. Time-averaged values of three velocity components and surface pressure coefficients, and turbulent statistics, i.e. turbulent kinetic energy and normal component of the Reynolds stresses are presented. Furthermore, the time-averaged two-dimensional (2D) velocity magnitude over the pedestrian height are presented for evaluating the gust factor. The presented database is useful for the validation of computational fluid dynamics (CFD) models and turbulent model developments for urban and building-related studies.

face pressure coefficients, and turbulent statistics, i.e. turbulent kinetic energy and normal component of the Reynolds stresses are presented. Furthermore, the time-averaged twodimensional (2D) velocity magnitude over the pedestrian height are presented for evaluating the gust factor. The presented database is useful for the validation of computational fluid dynamics (CFD) models and turbulent model developments for urban and building-related studies. ©

Value of the Data
• The dataset is intended to provide a high tempo-spatial resolution database for assessing the wind environment around a group of buildings in presence of a high-rise building to assess the complex interactions of the flow around the high-rise building and the street flow. • The dataset can be used by researchers and CFD users in the field of wind environment and urban climate simulations for validation studies.
• The dataset can be used as a benchmark for accuracy assessment of different CFD settings, including grid resolution, turbulence models, numerical schemes, steady-state or transient analysis [2][3][4] . • The dataset can be utilized as a high-quality source for calibration of the closure coefficients of turbulence models [5][6][7] .

Data Description
The dataset presented in this paper are described in the following: Wind tunnel profile of the approaching flow (supplementary file Table 1): The wind tunnel profiles of the time-averaged streamwise velocity, turbulent kinetic energy, and fluctuating velocity components in the streamwise, lateral, and vertical directions, which are measured at the center of the empty turntable are shown in this file.
Turbulent statistics over the vertical plane for Case 1H (supplementary file The data presented within this paper are completed with the coordinates of the measurement points over horizontal and vertical planes for the velocity measurements for Case 1H and Case 3H, which are shown in Fig. 3 (see Section 3 of this paper).

Building configuration
The building configuration, as shown in Fig. 1 , is a group of nine generic cubic buildings which are arranged in a regular form with a planar area ratio of λ p = 0 . 25 . The planar area ratio is defined as: where B and D are the breadth and depth of the building, respectively, and W is the distance between the buildings. The distance between all buildings in the lateral and streamwise directions is 0 .  benchmark [ 8 , 9 ]. Furthermore, this configuration was used in several CFD validation studies, e.g. [10][11][12] .

Experimental settings
Experiments were performed in the atmospheric boundary layer wind tunnel at the Niigata Institute of Technology [ 13 , 14 ]. The test section length is 13 m and the cross-section dimension is 1 . 8 × 1 . 8 m . The experimental set-up for the velocity and surface pressure measurements is shown in Fig. 2 . The building models were made of 3 mm-thick acrylic plates.
The reference velocity measured at the center of the empty turntable at H = 0 . 1 m is U H = 3 . 1 m s . The building Reynolds number, which is determined by H and U H , is 2 . 1 × 10 4 . The aerodynamic roughness length z o , deduced from the line fitted to the mean velocity profile of the approaching flow, was 0 . 0 0 02 m .

Measurement details
Velocity measurements : Three components of the instantaneous velocity vector u i ( i stands for The three velocity components were measured by rotating the probe in the corresponding direction. Time-averaging was conducted with a sampling rate of 10 0 0 Hz for a period of 60 s to obtain statistically stationary values for the time-averaged velocity components ( U i ) and fluctuat- where v m −xy for each segment. The final GF is the average of GF for all segments. The measurement relative expanded uncertainty [15] of the velocity components was less than 10%.
Wind pressure measurements : The static pressures on the building surfaces were measured using a multipoint transducer (Kyowa Electronic Instruments; F94-2206). Long, thin tubes were used to connect the taps to the transducers located outside the wind tunnel. Time-averaging was conducted with a sampling rate of 100 Hz for a period of 60 seconds. The pressure coefficient C p is defined as: C p = ( P − P re f ) / 1 2 ρU 2 H , where P and P re f are the static pressure over the building and the reference static pressure at a point not affected by the building, respectively, and ρ is the air density. The measurement relative expanded uncertainty [15] of the pressure coefficient was less than 5%.

Ethics Statement
There is no ethical issue in this paper.

Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships which have or could be perceived to have influenced the work reported in this article.