**5. Concluding remarks**

In this work, different boundary layer flows were experimentally analyzed. The BLF developed at the UNNE wind tunnel include a naturally developed boundary layer with the empty wind tunnel, a full-depth ABL generated by the Counihan method, and a part-depth ABL simulated by the Standen method.

A simplified analysis considering the depth of the neutral ABL of about 500 m compared with the gradient height (0.30 m) obtained for the empty tunnel implicates a scale factor of 1/1650. In addition, turbulence intensity values inside the boundary layer are always minor than 10%, concluding that this boundary layer flow is not appropriate to wind engineering experiments.

Full-depth and part-depth simulations developed in the UNNE wind tunnel seem to show adequate performance. It is observed that values of measured turbulence intensity are lower than the values in the neutral atmosphere, mainly in the positions above, but other authors obtained similar results. Dimensionless spectral comparison indicates a deviation of the experimental results with respect to design spectra, but it is possible that parameters used to normalize the spectrum are not fully adequate. Some studies are being developed to verify this behavior.

Comparison of ABL flows obtained with low velocities and the ABL flow obtained with high velocity at the UFRGS wind tunnel indicates an acceptable behavior of the mean velocity and turbulence intensity distribution. Dimensionless spectra were not obtained for measurements with low velocities. However, a poor spectral definition was observed for measurements realized at the lowest velocity.

Five recent applications of ABL simulations in both wind tunnels (UNNE and UFRGS) are presented. A study of local wind loads on a high-rise building considering the urban environment and the surrounding topography realized in the UNNE wind tunnel, where full-depth simulation flows were used. An experimental study of a low structure, specifically an airport where a part-depth boundary layer simulation developed at the UNNE wind tunnel, was utilized. Some wind tunnel applications to the aerodynamic analysis of cable-stayed bridges are shown where different incident flows were used.

Then, a pollutant atmospheric dispersion study realized in the UFRGS wind tunnel was shown. ABL flows obtained with low velocities were used to simulate the gas plume emission. A case study applied to the Brazilian Launch Center of Alcântara to evaluate the emitted gas dispersion process is also shown.

Finally, a recent wind tunnel study of the flow in the wake of wind turbines is presented. Measurements of the flow characteristics upwind and downwind of the turbine rotor were analyzed. Comparison of the turbulence spectra were also developed to evaluate the rotor effects on the turbine wake flow.

Also numerical methods are used mainly for forecasting and studying the dynamics of the airflow over large surfaces, usually with domains of several square kilometers. The Weather Research and Forecasting (WRF) model, which is a numerical weather prediction and atmospheric simulation system, is an example of this type of computational modeling. The size of the domain of the simulation of these models is much larger than the simulated spaces of boundary layer flows in a wind tunnel. However, some efforts are being made to link results from computational model and experimental data. In South America, for example, a WRF model was used by Puliafito et al. [26] to simulate mesoscale events of Zonda winds, and the obtained results were compared with meteorological data. The next objective of this research is to try the physical simulation of these events in a wind tunnel [27].
