On the separation of hydrodynamic and acoustic waves in linear free‐shear flows

Abstract

The governing equations for sound propagation through free‐shear flows, like jets and mixing layers, are the linearized Euler equations. These equations support both hydrodynamic and acoustic waves. For an aeroacoustician wishing to study the refraction effects of a sound source by shear flows, it is important to distinguish the acoustic solution from the hydrodynamic waves. Agarwal et al. (AIAA J., Vol. 42, No. 1, 2004) presented a technique to achieve this in the frequency domain. In this talk, we present a time‐domain technique to separate the hydrodynamic and acoustic waves. The idea is to implement a filter that filters out only the acoustic wave solution from the linearized Euler equations. Some sample solutions are presented for two‐dimensional free‐shear flows and comparisons are made against known analytical solution for parallel flows and from solution obtained by approximate methods, which have a limited range of applicability. The advantage for the present technique is that it is applicable to...