Physical sources of sound in laminar and turbulent jets

Abstract

An algorithm to compute the physical sources of sound in a jet is introduced. The algorithm is based on spatio-temporal ltering of the flow eld and is applicable to multi- frequency sources. It is rst applied to an axisymmetric laminar jet and the resulting sources are validated successfully. It is shown that the dominant source mechanism is the \shear-noise term. The algorithm is also applied to a fully turbulent jet obtained by Direct Numerical Simulation. The sound sources are computed for the axisymmetric mode over a broad range of frequencies. Various physical sources of sound, including monopoles, wavepackets, and vortex pairings are identied. © 2011 by the author(s). Published by the ..