Implementation of nonreflecting boundary conditions for the nonlinear Euler equations

Atassi, Oliver; Galán, José M.

doi:10.1016/j.jcp.2007.09.028

Cited by 6 publications

(2 citation statements)

References 35 publications

(65 reference statements)

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“…In what follows, we nondimensionalize all lengths by the outer radius of the duct, r t , the velocity by the inlet speed of sound, c 1 , and the density by the inlet mean density, ρ 1 . Nonreflecting inflow/outflow boundary conditions are prescribed as described in [21], [22]. The pressure at the inflow and outflow boundaries, respectively, is given by the relations…”

Section: Formulation: Acoustic Wave Interaction With a Heat Sourcementioning

confidence: 99%

Future challenges in computational aeroacoustics for fan broadband and combustor noise

Atassi

Gilson²

2010

Procedia Engineering

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Two critical areas for the design of quiet gas turbine engines, fan broadband and combustor noise, are briefly reviewed. Both of these noise sources are sensitive to local aerodynamic and geometric variations and thus are ideally suited for analysis by computational aeroacoustic methods. To demonstrate this point for combustor noise and show areas where improved understanding is needed, the scattering of an acoustic wave by a localized heat source is studied. The heat source produces gradients in the mean flow and the speed of sound that scatter the incident duct acoustic mode into vortical, entropic, and higher order acoustic modes. Solutions to the Euler equations are computed to (i) understand how variations in the amplitude and axial extent of a steady heat source and (ii) how unsteady heat release can modify the scattered solution. For an acoustic excitation interacting with a steady heat source, significant entropy waves are produced as the net heat addition increases at the expense of the transmitted acoustic energy. When the net heat addition is held constant, increasing the axial extent of the heat source results in a reduction of the entropy waves produced downstream and a corresponding increase in the downstream scattered acoustic energy. When unsteady heat release which is proportional to mass flow fluctuations in the duct is considered, a significant reduction in the entropy occurs and a corresponding increase in the transmitted and reflected acoustic waves occurs. These results suggest that the dominance of the indirect and direct combustor noise mechanisms are highly sensitive to the heat source lengthscale relative to the acoustic lengthscale and the character of the unsteady heat release.

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Section: Formulation: Acoustic Wave Interaction With a Heat Sourcementioning

confidence: 99%

Future challenges in computational aeroacoustics for fan broadband and combustor noise

Atassi

Gilson²

2010

Procedia Engineering

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“…Numerical methods need efficient and easy to implement techniques to truncate the computational domain without disturbing the solution of the original problem. Several efficient methods have been developed in the literature to cope with unbounded domain problem: the Non-Reflecting Boundary Condition (NRBC) methods [1][2][3] using the operator commonly called Dirichlet-to-Neumann (DtN) based on an analytical representation of the external field and needing particular geometries; the Boundary Element Methods (BEM) [4] which is another exact non-reflecting and non-local boundary condition whose main drawbacks are the singularity and the non-uniqueness of the solutions at some characteristic frequencies; and the Infinite Element Methods (IEM) [5] whose efficiency depends on the choice of the multipole expansion functions in the radial direction and on the truncation of the radial order.…”

Section: Introductionmentioning

confidence: 99%

Perfectly Matched Layer for Galbrun׳s aeroacoustic equation in a cylindrical coordinates system with an axial and a swirling steady mean flow

Baccouche

Tahar

Moreau

2016

Journal of Sound and Vibration

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Reprint of:Future Challenges in Computational Aeroacoustics for Fan Broadband and Combustor Noise

Atassi

Gilson²

2010

Procedia IUTAM

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Implementation of nonreflecting boundary conditions for the nonlinear Euler equations

Cited by 6 publications

References 35 publications

Future challenges in computational aeroacoustics for fan broadband and combustor noise

Future challenges in computational aeroacoustics for fan broadband and combustor noise

Perfectly Matched Layer for Galbrun׳s aeroacoustic equation in a cylindrical coordinates system with an axial and a swirling steady mean flow

Reprint of:Future Challenges in Computational Aeroacoustics for Fan Broadband and Combustor Noise

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