https://www.colonius.caltech.edu/pdfs/ColoniusLele2004.pdf

Computational aeroacoustics: progress on nonlinear problems of sound generation

Broadband slat noise prediction based on CAA and stochastic sound sources from a fast random particle-mesh (RPM) method

Several methods for the prediction of jet noise are described. All but one of the noise prediction schemes are based on Lighthill's or Lilley's acoustic analogy, whereas the other is the jet noise generation model recently proposed by Tam and Auriault. In all of the approaches, some assumptions must be made concerning the statistical properties of the turbulent sources. In each case the characteristic scales of the turbulence are obtained from a solution of the Reynolds-averaged Navier-Stokes equation using a kappa-sigma turbulence model. It is shown that, for the same level of empiricism, Tam and Auriault's model yields better agreement with experimental noise measurements than the acoustic analogy. It is then shown that this result is not because of some fundamental flaw in the acoustic analogy approach, but instead is associated with the assumptions made in the approximation of the turbulent source statistics. If consistent assumptions are made, both the acoustic analogy and Tam and Auriault's model yield identical noise predictions. In conclusion, a proposal is presented for an acoustic analogy that provides a clearer identification of the equivalent source mechanisms, as is a discussion of noise prediction issues that remain to be resolved.

/pdf/acoustic-analogy-and-alternative-theories-for-jet-noise-2bl9szc9vb.pdf

Acoustic Analogy and Alternative Theories for Jet Noise Prediction

On the simulation of trailing edge noise with a hybrid LES/APE method

Linearized perturbed compressible equations for low Mach number aeroacoustics

Acoustic perturbation equations based on flow decomposition via source filtering

To compare numerical methods and boundary conditions for computational aeroacoustics (CAA) two-dimensional aeroacoustic benchmark problems are solved. The numerical methods are the dispersion relation preserving scheme (DRP) of Tam et al. [1] and the compact finite difference scheme proposed by Lele [2]. The acoustic boundary conditions applied are the non-reflecting boundary condition of Thompson [4,5] and the asymptotic boundary condition of Tam [2]. The benchmark problems used describe the propagation of acoustic, vorticity and entropy waves relative to a mean flow with varied flow direction.

R. Ewert

Papers

Acoustic perturbation equations based on flow decomposition via source filtering

Comparison of Numerical Schemes Applied to CAA Problems