Coupled Discontinuous Galerkin/Finite Difference Solver on Hybrid Meshes for Computational Aeroacoustics

Léger, Raphaël; Peyret, Christophe; Piperno, Serge

doi:10.2514/1.j051110

Cited by 17 publications

(18 citation statements)

References 12 publications

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“…The ONERA unstructured computational aeroacoustics (CAA) code SPACE 48,49 is used in the zone Z2. The full Euler equations are solved through a nodal discontinuous Galerkin method using high-order polynomial elements without order limit.…”

Section: Acoustic Computationmentioning

confidence: 99%

Accurate simulation of the noise generated by a hot supersonic jet including turbulence tripping and nonlinear acoustic propagation

et al. 2019

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A procedure to accurately simulate a free hot supersonic jet and its associated noise, which uses simultaneously a turbulence tripping method and a two-way coupling between a flow solver and a nonlinear acoustic solver, is proposed in this study. A Mach 3.1 overexpanded hot jet is computed via a large-eddy simulation by solving the filtered Navier-Stokes equations with a finite volume method on unstructured grids. The resulting noise is propagated in the far field by solving the full Euler equations with a high-order discontinuous Galerkin method on unstructured grids. The full convergent-divergent nozzle is explicitly included in the computational domain thanks to the unstructured flow solver. Both a refined grid and a geometrical boundary layer tripping in the convergent are used to get highly disturbed turbulent conditions at the nozzle lips. The flow field appears to agree with the expected turbulence behavior and the available experimental data. The jet development shows significant improvement compared to similar past simulations. The far field acoustic levels are finely recovered at most of observation angles. An analysis of the acoustic near and far fields is then performed. The studied conditions lead to strong shock-associated noise and Mach wave emission. The spatio-frequency and azimuthal content of the acoustic field is described in order to identify the main noise properties. A particular noise component, different from screech tones and radiating upstream like Mach waves, is highlighted. Nonlinear propagation effects are finally quantified through specific metrics. They are found significant in both the near and the far fields which justifies the use of a nonlinear acoustic solver.

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Section: Acoustic Computationmentioning

confidence: 99%

Accurate simulation of the noise generated by a hot supersonic jet including turbulence tripping and nonlinear acoustic propagation

et al. 2019

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“…The spectral interpolation of the Fourier PSTD solutions to obtain the values of the acoustic variables at the DG nodes is performed using Eqs. (10). The interpolation is done by a transformation of the Fourier PSTD solutions to the wavenumber domain, where the transformed variables are multiplied with the exponential that accounts for the location of the DG nodes.…”

Section: Hybridization Processmentioning

confidence: 99%

“…The idea of coupling methodologies in order to get the benefits of each solver has already been presented by many authors as, for instance, Utzmann et al, 9 Léger et al 10 and, recently, Lisitsa et al 11 The present paper introduces a hybrid approach to solve the linearized Euler equations (LEE), coupling Fourier PSTD with the nodal Discontinuous Galerkin (DG) method. DG exhibits almost no restrictions with respect to geometrical complexity or boundary conditions, and has been successfully implemented for aeroacoustics applications, for instance.…”

Section: Introductionmentioning

confidence: 99%

A Hybrid PSTD/DG Method to Solve the Linearized Euler Equations: Optimization and Accuracy

Munoz

Hornikx

2016

22nd AIAA/CEAS Aeroacoustics Conference

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The wave-based Fourier Pseudospectral time-domain (Fourier PSTD) method was shown to be an effective way of modelling acoustic propagation problems as described by the linearized Euler equations (LEE), but is limited to real-valued frequency independent boundary conditions and predominantly staircase-like boundary shapes. This paper presents a hybrid approach to solve the LEE, coupling Fourier PSTD with a nodal Discontinuous Galerkin (DG) method. DG exhibits almost no restrictions with respect to geometrical complexity or boundary conditions. The aim of this novel method is to allow the computation of arbitrary boundary conditions and complex geometries by using the benefits of DG, while keeping Fourier PSTD in the bulk of the domain. The hybridization approach is based on conformal meshes to avoid spatial interpolation of the DG solutions when transferring values from DG to Fourier PSTD and a Gaussian window function to enforce periodicity, while the data transfer from Fourier PSTD to DG is done utilizing spectral interpolation of the Fourier PSTD solutions. Furthermore, the coupling algorithm includes a low-pass filtering approach to suppress instabilities arising from the Fourier PSTD solver. In this paper, the influence of the main parameters of the data-exchange areas and the Gaussian window function on the hybrid method results, is investigated. The precision of the hybrid approach is presented and compared with the precision of the Fourier PSTD standalone solver, showing no significant additional error from the hybrid approach for a suitable selection of parameters. Nomenclature

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“…It suggests that two-way coupling methods need also to be investigated. Implementations of such methods can be found in the works of Borrel et al [30] or Léger et al [31] for two-dimensional and Labbé et al [32] for tri-dimensional applications with structured solvers, but tri-dimensional fully unstructured configurations are quite rare. Langenais et al [15] have carried out a two-way coupled unstructured NS-Euler computation to simulate the noise generated by an overexpanded Mach 3.1 free hot jet.…”

Section: Introductionmentioning

confidence: 99%

“…Benchmark problems have then been applied to various numerical methods for validation purposes. In particular, Harris et al [28] have applied a one-way NS-Euler coupling method to a 2D twocylinder acoustic scattering problem, Léger et al [31] have also validated a two-way LEE-LEE coupling method on several 2D problems of diffraction by cylinders and finally, Labbé et al [29] have simulated a 2D convected isentropic vortex, as proposed first by Yee et al [37], using a one-way NS-Euler coupling method. However, the ability of a two-way coupling method to handle nonlinear propagation effects, acoustic feedback effects and realistic installation effects without significant spurious noise is not often assessed in the literature.…”

Section: Introductionmentioning

confidence: 99%

Assessment of a Two-Way Coupling Methodology Between a Flow and a High-Order Nonlinear Acoustic Unstructured Solvers

Langenais

Vincent

Peyret

et al. 2018

Flow Turbulence Combust

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A two-way coupling on unstructured meshes between a flow and a high-order acoustic solvers for jet noise prediction is considered. The flow simulation aims at generating acoustic sources in the near field while the acoustic simulation solves the full Euler equations, thanks to a discontinuous Galerkin method, in order to take into account nonlinear acoustic propagation effects. This methodology is firstly validated on academic cases involving nonlinear sound propagation, shock waves and convection of aerodynamic perturbations. The results are compared to analytical solutions and direct computations. A good behaviour of the coupling is found regarding the targeted space applications. An application on a launch pad model is then simulated to demonstrate the robustness and reliability of the present approach.

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Coupled Discontinuous Galerkin/Finite Difference Solver on Hybrid Meshes for Computational Aeroacoustics

Cited by 17 publications

References 12 publications

Accurate simulation of the noise generated by a hot supersonic jet including turbulence tripping and nonlinear acoustic propagation

Accurate simulation of the noise generated by a hot supersonic jet including turbulence tripping and nonlinear acoustic propagation

A Hybrid PSTD/DG Method to Solve the Linearized Euler Equations: Optimization and Accuracy

Assessment of a Two-Way Coupling Methodology Between a Flow and a High-Order Nonlinear Acoustic Unstructured Solvers

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