Revisiting the amplitude modulation in wall-bounded turbulence: towards a robust definition

Authors: Dogan, E.D., Örlü, R., Gatti, D., Vinuesa, R., Schlatter, P.
Document Type: Article
Pubstate: Accepted
Journal: 12th ERCOFTAC Symp. on Engineering Turbulence Modeling and Measurements (ETMM12), Montpellier, France, September 26-28
Year: 2018


The present study revisits the amplitude modulation phenomenon, specifically for the robustness in its quantification. To achieve this, a well-resolved large-eddy simulation (LES) data set at Re θ ≈ 8200 is used. First, the fluctuating streamwise velocity signal is decomposed into its small-and large-scale components using both Fourier filters and empirical mode decomposition (EMD), allowing the comparison among different separation filters. The effects of these filters on various definitions for quantifying the amplitude modulation have been discussed. False positive identification of the amplitude modulation has also been tested using a randomised signal. Finally, the impact of the inclination angle of the large-scale structures on the modulation quantification has been assessed.