Acoustic and turbulent wavenumbers separation in wall pressure array signals using EMD in spatial domain

Empirical mode decomposition (EMD) is a powerful "time-frequency" tool that is used here in the spatial domain to filter out at each instant, short scale wall pressure fluctuations measured by a linear microphone array beneath a boundary layer. A frequency over streamwise wavenumber representation is used to separate acoustic and turbulent energy: it is obtained by a classical spatial-correlogram which is performed either on original signals or on spatial EMD-filtered signals. It is shown how spatial EMD filtering reduces the spread of the convective energy due to the truncation effects and is tuned to improve the separation of the acoustical energy out of the turbulent energy.