Spectral analysis of pressures measured on two high-rise building models in side-by-side arrangement

Pressure measurements on an isolated square plan form high-rise building model and two square high-rise building models in side-by-side arrangement were analysed using the Fast Fourier Transform (FFT) to define peak frequencies resulting from interference. For the isolated building model, a peak in the power spectrum was determined on the side face at a reduced frequency of fred = fB/UH = 0.08. This value corresponds with St = 0.09, which is a typical value for the vortex shedding process for this type of model. In the side-by-side arrangement, spectral peaks were observed at fred = 0.03, 0.09, and 0.12 on the face inside the passage. The first peak is related to vortex shedding of the combination of two models, the second peak to vortex shedding of the single model. The last peak is caused by reattachment of the shear layer. Analysis of the reduced power (fSpp/qH2) in three frequency bands, fred = 0.01 – 0.06, 0.06 – 0.11 and 0.11 – 0.16, shows an increase in power near the entrance and a decrease near the exit of the passage in all bands with decreasing separation distance. These changes in the spectral power distribution indicate the processes related to the determined spectral peaks (fred = 0.03, 0.09, and 0.12) increase in intensity, but their region of influence in the passage decreases.