Extracting accurately and efficiently burst events of wall turbulence

Flow field measurement of turbulent boundary layer was accomplished in a gravitational low-speed water tunnel set up by us. The velocity signal of a test point in logarithmic layer is analyzed respectively with two methods (autocorrelation method and wavelet transform method), and the results and their analysis demonstrate preliminarily that the autocorrelation method has high precision for the detection of average burst period, while the wavelet transform method can be used to extract burst events but with low precision. Consequently, an improved method with high precision and efficiency is put forward based both on autocorrelation and wavelet transform, and the specific implementation steps are summarized in section 3 of the full paper. Compared with old methods, our improved method can indeed extract burst events of wall turbulence both accurately and efficiently.