Numerical prediction method for the acoustic characterization of network elements in presence of mean flow

In the present paper a numerical prediction method for the acoustic characterization of network elements is developed. The acoustic field inside the tested elements is evaluated solving the linearized Euler equations (LEE), or the acoustic perturbation equations (APE), with a discontinuous Galerkin method (DGM). The pressure field is post-processed with a plane wave decomposition method to obtained left- and right-running plane waves at each element port. To characterize the element either the scattering matrix or the impedance is evaluated. For the solution of the hydrodynamic mean flow field the open source Open-FOAM toolbox is used. The numerical method is applied to evaluate the scattering matrix of a sudden area discontinuity both with medium at rest and in presence of mean flow and to evaluate the impedance of an orifice plate as function of the frequency. For both cases the results obtained by the numerical simulations are compared with experimental data