Wavelet analysis of unsteady flows: Application on the determination of the Strouhal number of the transient wake behind a single cylinder

This paper presents experimental results of the accelerating and decelerating flow in the wake of a cylinder obtained by means of hot wire anemometry measurements in a wind tunnel with high blockage ratio. The analysis was done in Fourier and wavelet spaces. The Strouhal number for Reynolds numbers up to 3 × 104 was studied in a transient flow and compared with the results obtained from steady flows at several velocities uniformly distributed from Re = 1.7 × 103 to 3 × 104. Results show that the wavelet analysis is a valuable tool to deal with both transient and stationary random phenomena and that is able to capture the characteristics of the transient flow as well as the Fourier analysis can do with the steady state acquisitions.