Abstract

This seminar will present a journey into the acoustics of turbulent flows. It will start with jet noise, one of the most challenging topics in fluid mechanics, for which we have developed a new theory for identifying the noise sources. It relies on filtering the flow in the frequency-wavenumber domain to separate hydrodynamic fluctuations from acoustic fluctuations. The theory has been applied to jets obtained by direct numerical simulation and it provides greater physical insights than classical acoustic analogies.

We will then discuss recent theoretical findings on trailing edge noise, the dominant source of wind turbine noise. These findings have put an end to a long standing controversy on a popular method for predicting trailing edge noise for rotating aerofoils. They show how one can extend theoretical, numerical or experimental results for an aerofoil sitting in a wind tunnel to a rotating aerofoil.

We will conclude by focusing on one key aspect of both problems: understanding the peculiar geometry of acoustic waves in fluid flows. This geometry will be brought to light by introducing a newly defined acoustic space-time inspired by the theory of special relativity.