**3.2 Analysis of the model scale factor**

The evaluation of the model scale factor was only realized with high velocity *Uref* = 35 m/s. The Cook's procedure [5] was applied using the form proposed by Blessmann [11] and a value of the scale factor at each measurement position by means of the roughness length *z*0 and the integral scale *Lu*. Finally, a mean value of the model scale factor of 400 was calculated, and it is considered the same in the case of low velocities based on the maintenance of the mean statistical parameters.

**Figure 11.** *Perforated spires, barrier, and roughness elements to simulate a full-depth atmospheric boundary layer.*

**135**

**Figure 13.**

*boundary layer simulation.*

**Figure 12.**

*depth boundary layer simulation.*

*Physical Models of Atmospheric Boundary Layer Flows: Some Developments and Recent…*

**4. Recent applications of simulated boundary layer flows**

Some recent wind engineering applications of the ABL simulations are presented. In general, this type of applications was referred to wind action on civil structures, but new studies related with ambient evaluation, urban design, and wind energy are being developed. In this work, experimental studies related to

*Spectral density function measured with low velocity at two positions* z *= 0.15 m and 0.35 m for a full-depth* 

*Vertical mean velocity and turbulence intensity profiles measured with different reference velocities for a full-*

*DOI: http://dx.doi.org/10.5772/intechopen.86483*

*Physical Models of Atmospheric Boundary Layer Flows: Some Developments and Recent… DOI: http://dx.doi.org/10.5772/intechopen.86483*

**Figure 12.**

*Boundary Layer Flows - Theory, Applications and Numerical Methods*

ness *H* = 0.60 m.

laser Doppler velocimetry [12].

**3.2 Analysis of the model scale factor**

**Figure 12** shows the non-dimensional profiles obtained with low velocities *Uref* = 1 and 3.5 m/s, respectively. These profiles are compared with the values obtained with the highest mean velocity achievable in the wind tunnel (*Uref* ≈ 35 m/s). The mean velocity profile given by the power law expression (Eq. (2)) is also included in this graph, being the power law exponent *α* equal to 0.23 and the boundary layer thick-

Also, turbulence intensities measured in correspondence to *Uref* = 1, 3.5, and 35 m/s are shown in **Figure 12**. Turbulence intensity values corresponding to 3.5 m/s are slightly higher than those obtained at high velocity, which is a behavior commonly observed at low velocities. For measurements at velocity *Uref* = 1 m/s, it is possible to observe even larger deviations in comparison with 3.5 and 35 m/s cases that can be attributed to extremely low velocity. It is worth noting that with these velocity magnitudes, the relative errors affecting the hot-wire anemometer technique are larger than for measurements at high velocities. This kind of measurement deviation was also observed in similar wind tunnel tests using three-dimensional

Power spectra of the velocity fluctuations obtained at two different positions, *z* = 0.15 and 0.35 m with low velocities *Uref* = 1 and 3.5 m/s, respectively, are presented in **Figure 13**. Sampling series used for the spectral analysis were obtained with an acquisition frequency of 1024 Hz. A poor definition of the Kolmogorov's inertial subrange is observed for the spectra measured at velocity *Uref* = 1 m/s.

The evaluation of the model scale factor was only realized with high velocity *Uref* = 35 m/s. The Cook's procedure [5] was applied using the form proposed by Blessmann [11] and a value of the scale factor at each measurement position by means of the roughness length *z*0 and the integral scale *Lu*. Finally, a mean value of the model scale factor of 400 was calculated, and it is considered the same in the case of low velocities based on the maintenance of the mean statistical parameters.

*Perforated spires, barrier, and roughness elements to simulate a full-depth atmospheric boundary layer.*

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**Figure 11.**

*Vertical mean velocity and turbulence intensity profiles measured with different reference velocities for a fulldepth boundary layer simulation.*

**Figure 13.**

*Spectral density function measured with low velocity at two positions* z *= 0.15 m and 0.35 m for a full-depth boundary layer simulation.*
