The perturbed low Mach number approximation for the aeroacoustic computation of anisothermal flows

Cyril Nana (1) , David Marx (1) , Christian Prax (1) , Véronique Fortuné (1)

1 PPrime [Poitiers] - Institut Pprime [UPR 3346]

We present here a new hybrid method for the computation of the sound emitted by subsonic flows with temperature and density inhomogeneities. This method consists in splitting the flow field into a hydrodynamic part and an acoustic one thanks to a low Mach number approximation of the Navier-Stokes equations. We therefore consider the hydrodynamic part to be quasi incompressible. The acoustic quantities are obtained by a perturbation of the compressible Navier-Stokes equations from which hydrodynamic quantities are subtracted. These become a source term based on the convective derivative of the hydrodynamic pressure. The method has been successfully applied to isothermal and anisothermal excited mixing layers. The validity of the proposed method is assessed by comparison to a compressible direct numerical simulation on the one hand and to LEE computations with different source terms on the other hand.

Mots clés: shear layer; anisothermal subsonic flow; computational aeroacoustics; hybrid method

Domaines: Acoustique [physics.class-ph]

Cyril Nana, David Marx, Christian Prax, Véronique Fortuné. The perturbed low Mach number approximation for the aeroacoustic computation of anisothermal flows. Acoustics 2012, Apr 2012, Nantes, France. ⟨hal-00810971⟩