Wind tunnel simulation of atmospheric turbulent flow over a flat terrain

Abstract

Wind tunnel experiment on the turbulence characteristics over a flat terrain was examined on the basis of field data. The wind tunnel results were compared with the field data in which vertical distributions of mean wind speed, turbulence intensity, Reynolds stress, and energy spectra and cospectra had been obtained from a 200 m meteorological tower at six levels under neutral atmospheric conditions. The experiment with 1 1000 scaled model was carried out under the following similarity conditions: (1) the vertical profile of mean wind speed is set to be similar to the field one, and (2) the experimental Reynolds number is set sufficiently large (i.e. Reynolds number independence). The critical Reynolds number over the flat terrain was found to be 3.7 × 10 4. The wind tunnel results of vertical profiles of turbulence intensity and normalized Reynolds stress ( − uw U 2 ) were similar to the field results. Moreover, the similarity of spectra and cospectra was obtained concerning the spectral structure and the height dependence. From the agreement between the wind tunnel and field spectra with nondimensional frequency, it follows that the field time scale, T f is reduced to the wind tunnel time scale, T w by a factor of α β , where α is the wind tunnel reduction scale and β is the ratio of the wind tunnel to field wind speeds.