Estimation of the vortex shedding frequency of a 2-D building using correlation and the POD methods

A method was developed to estimate the frequency of vortex shedding in turbulent flow. In this method, a Particle Image Velocimetry (PIV) system was used to acquire the original complex turbulent flow field. Proper orthogonal decomposition (POD) analysis was applied to the PIV data in order to extract the main structure of the overall physical characteristics from the measured wind velocity field. A bivariate correlation was introduced to the POD results to determine the correlation of the vortex structures. Fast Fourier Transform (FFT) was employed to perform a power spectra analysis of these correlation coefficients to obtain the frequency of vortex shedding from the power peak. A PIV experiment was carried out within a wind tunnel simulated atmospheric surface layer, which involved a two-dimensional building problem with wind from two directions. The developed method was applied to the PIV experimental data and the frequency of vortex shedding was successfully extracted. The results show that the frequency of vortex shedding increases with increase in incoming flow velocity for both wind directions.