## 1 Introduction  
Atmospheric boundary layer (ABL) wind tunnel model tests are the most widely-employed approaches for wind-engineering research and design today. As physical modeling practices, the accuracies of the ABL wind tunnel model tests draw the attention of the wind engineering community. Until today, hundreds of research projects compared the wind effects or wind-induced structural responses measured on the engineering sites with the corresponding wind tunnel model test data. The majority of these comparisons suggested that the full-scale/model test discrepancies were noticeable. Many researchers subjectively inferred that two reasons should be responsible for the inaccuracies of ABL wind tunnel model tests. First, relying on passive simulation devices, complete turbulent flow characteristics of the realistic ABL flow field cannot be truthfully simulated in a traditional passive wind tunnel (the corresponding influences are referred to as flow characteristic effects hereinafter) [1; 2; 3]. Wind tunnel model tests treat empirical ABL flow characteristics presented in the Codes of Practice and monographs as simulation targets. However, it was found that the turbulent flow characteristics simulatedin the wind tunnel deviated from their simulation targets in many cases, causing significant negative effects. According to [PERSON] [4], the realistic mean wind speed profiles could be correctly simulated using spires and roughness elements in the wind tunnel, and the simulated turbulence intensities and power spectral densities were accurate below a certain height. However, when the height was increased, the simulated turbulence intensities were sometimes lower than their simulation targets, and the simulated power spectral densities became unrealistic. The simulated turbulence integral scale decreased with the increase in height, which was against the physical truth. In the history of the wind engineering community, [PERSON] [1] compared the wind pressures measured on a single-family dwelling with results obtained from a 1:50 scale model placed in a turbulent boundary layer in 1975. It was shown that the fluctuating wind pressure coefficients obtained from the model test were consistently low, which was attributed to the improper simulation of the lower portion of the ABL in the wind tunnel. [PERSON] et al. [2] modeled a two-story house at Aylesbury at 1:500 scale in a ABL wind tunnel to compare with the full-scale measurement results. The roughness length simulated in the wind tunnel was found to be too limited to characterize the local roughness near the measuring site, and it was suggested that the traditionally used similarity parameter in the wind tunnel was probably not sufficient to ensure similarity. [PERSON] [3] compared the surface pressures measured on a low-rise building model to the full-scale data taken on a Silsoe Structures Building. Comparisons between the model and full-scale surface pressure spectra at two taps suggested that differences were notable. It was indicated that the poor comparison was due to the differences in the full-scale and wind-tunnel approach flows. To deal with this issue, actively controlled devices are placed in the beginning of the wind tunnel's working section to increase the turbulence intensity and the turbulence integral scale of the simulated flow by some researchers. The employed actively controlled devices included vibrating grids and active vanes. Second, Reynolds number (Re) effects exist for wind tunnel model tests (the corresponding influences are referred to as Re effects hereinafter) [5; 6; 7; 8]. Basically, the flow separation location for flow around a bluff body without corners is sensitive to Re. Since the Re for model tests is usually two orders of magnitude smaller than the Re for the prototype flow event, significant distortions might be caused for the model test data. [PERSON] et al. [5] compared the detailed wind pressures measured on a Silsoe Structures Building at full scale and on a scaled model.