Wavelet-based method for burst detection

A method to detect energetic structures based on wavelet analysis is outlined. Combined with a quadrant decomposition the method may provide information about the scale dependency of ejection and sweep events. One advantage of this method compared to previously published algorithms is that there are no thresholds or grouping times involved. The method was applied to a number of zero pressure gradient boundary layer flows covering a large range of Reynolds numbers. It is shown that the duration of the ejections, over the entire boundary layer, scales with inner variables for a nide range of turbulent scales. The time between the events scale with inner variables in the immediate vicinity of the wall, but for gamma (+) greater than about 70, outer scaling proved to give the best collapse for the Re range investigated. (C) 2001 Published by The Japan Society of Fluid Mechanics and Elsevier Science B.V. All rights reserved.