Symposium of sound source mechanisms in turbulent shear flows

The question regarding the mechanisms by which heated turbulent flows convert vortical and thermal energy into acoustic energy remains as controversial as ever, despite over 50 years of intensive research in the field. The first golden age of aeroacoustics (1950s-1970s), where the analysis approach was largely theoretical, led to an impasse in terms of an unambiguous identification of causality (between vortical, thermal and acoustic motions) in the flow equations, and indeed a general unified theory of aeroacoustics was not achieved-this impasse is of course inextricably tied to the theoretical problems faced in the field of compressible turbulence. Many of the most sophisticated theoretical developments were difficult to assess, due to the complexity of the physical quantities identified as relevant to the jet noise problem. As a result, many of the ideas and theories which currently exist regarding noise sources in jets remain contentious, and, rather than serving as a guide for low-noise design, tend instead to generate controversy and disaccord.

Recent developments in terms of our capacity to both numerically and experimentally analyse the physics of compressible, turbulent flows have opened up new possibilities however. The objective of this workshop was to provide a platform for open discussion of these possibilities.

The workshop comprised invited talks, held over a two-day period, wherein recent studies, findings and ideas can be presented. Extended round-table sessions provided an opportunity for the community to think collectively, with a view to arriving at some consensus regarding priority future research goals, and the analysis tools which these will necessitate.