Wind-tunnel simulations of the suburban ABL and comparison with international standards

Abstract

Abstract. Three wind-tunnel simulations of the atmospheric boundary layer (ABL) flow in suburban country exposure were generated for length scale factors 1:400, 1:250 and 1:220 to investigate scale effects in wind-tunnel simulations of the suburban ABL, to address recommended wind characteristics for suburban exposures reported in international standards, and to test redesigned experimental hardware. Investigated parameters are mean velocity, turbulence intensity, turbulent Reynolds shear stress, integral length scale of turbulence and power spectral density of velocity fluctuations. Experimental results indicate it is possible to reproduce suburban natural winds in the wind tunnel at different length scales without significant influence of the simulation length scale on airflow characteristics. However, in the wind tunnel it was not possible to reproduce two characteristic phenomena observed in full-scale: dependence of integral length scales on reference wind velocity and a linear increase in integral length scales with height. Furthermore, in international standards there is a considerable scatter of recommended values for suburban wind characteristics. In particular, recommended integral length scales in ESDU 85020 (1985) are significantly larger than in other international standards. Truncated vortex generators applied in this study proved to be successful in part-depth suburban ABL wind-tunnel simulation that yield a novel methodology in studies on wind effects on structures and air pollution dispersion.

Comparison of Testing Results of Three Poorly Streamlined Entertainment Venues / Trijų Sudėtingo Pavidalo Pramoginių Statinių Maketų Bandymų Rezultatų Gretinimas

“…Building site conditions around the models were simulated by creation of vortexes in the boundary layer: large size vortexes were produced by jagged ledges on the front edge of the flat plate, small ones -by cube-shaped blocks (about 300 units). Such reproduction of the boundary layer is well studied by authors (Pavlovskij, Kuznecov 2009) and agrees with the foreign test practice (Lawson 2001;Kozmar 2011). a) b) Fig.…”

“…− an exact estimation of the load distribution is significant in many engineering applications (Lazzari et al 2009) as an example for optimisation problems; this allows to use materials taking into account structural reliability and to solve design problems at a higher level by using plastic deformations in case of variable loads (Jankovski, Atkočiūnas 2010, 2011Atkočiūnas, Venskus 2011).…”

Truncated vortex generators for part-depth wind-tunnel simulations of the atmospheric boundary layer flow

“…These results were compared with those of ESDU 74031 (1974). It is worth mentioning that wind specifications in major international standards and ESDU data sheets for suburban type terrain were compared elsewhere (Kozmar, 2011). The obtained turbulence intensities agree well with the ESDU 74031 (1974) data, i.e.…”

Simplified Wind Flow Model for the Estimation of Aerodynamic Effects on Small Structures

“…Performing wind tunnel experiments is more difficult for low-rise buildings than for high-rise buildings, as it entails partial simulation of the entire atmospheric boundary layer (ABL) and accurate modeling of wind turbulence in the lower reaches of the atmospheric surface layer (ASL) (Cermak 1995;Kozmar 2011;Stathopoulos 2003;Uematsu and Isyumov 1999). An international comparison reported by Fritz et al (2008) showed that, depending upon low-rise building dimensions, terrain exposure, and wind speed direction, the ratio between the largest and the smallest of the internal forces obtained from pressure measurements in six wind tunnels (Clemson University, Colorado State University, Texas Tech University, University of Western Ontario, Nantes Centre Scientifique et Technique du Bâtiment, and Tsukuba Building Research Institute) varied between 1.5 and 3.5.…”