Revisiting Lighthill’s acoustic analogy
* Präsentierender Autor
Zusammenfassung:Lighthill’s analogy is an exact reformulation of the fluid dynamic equations into an inhomogeneous wave equation. Thereby, the source term not only accounts for generation of sound but also for acoustic nonlinearity, convection and refraction of sound waves by the flow, as well as attenuation due to thermal and viscous actions. In order to compute the flow induced sound, one needs Lighthill’s tensor for which the full set of compressible flow dynamics equations have to be solved. However, for low Mach number flows, the Reynolds stress tensor is the leading order term, which can be obtained by an incompressible flow computation. Furthermore, we want to note that Lighthill’s inhomogeneous wave equation with the physical correct boundary conditions can be applied to any aeroacoustic application and the second spatial derivative of Lighthill’s tensor contains all physical aeroacoustic source terms.