TABLE OF CONTENTS Daniel J.Bodony and Sanjiva K.Lele
It can be said that most of the current research on the generation of sound by turbulent flows has had its origin in the prediction of jet noise (in particular the noise from jet exhaust plumes) by Lighthill (1952, 1954) in his two papers On Sound Generated Aerodynamically . [*] Lighthill s 
scaling of the radiated noise intensity, where U j is the jet exit velocity, gave engine manufacturers an initial tool by which to design quieter engines and led, in part, to the development of internal and external mixers and the turbofan engine. In the early 1970s, it became clear that a more detailed knowledge of the noise sources and the resulting radiation field would be needed to further reduce jet noise. Lilley s (1974) inhomogeneous convective wave equation, based on the work of Phillips (1960), gave further insight into the noise sources and attempted to separate out the sound-generation and sound-propagation processes that are present in the jet. [ ]
The numerical prediction of jet noise for design applications came with the introduction of the MGB [ ] jet prediction tool (Balsa et al. 1978). The MGB code uses a Reynolds-averaged Navier-Stokes (RANS) mean flow solution to define local length scale, time scale, and source strength parameters for a semiempirical source model. The source model is based on a simplified Lighthill quadmpole source term with an approximate high-frequency solution of Lilley s equation for...
