Time-Domain Numerical Simulation of a Flow-Impedance Tube

Özyörük, Yusuf; Long, Lyle N.; Jones, Michael G.

doi:10.1006/jcph.1998.5919

Cited by 108 publications

(64 citation statements)

References 15 publications

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“…[11], was collected specifically for the purpose of validating acoustic propagation codes and is the most comprehensive available. As such, it has been widely used to benchmark the use of flow impedance boundary conditions in numerical schemes [12,26,14,13].…”

Section: Validation Of the Propagation Methodologymentioning

confidence: 99%

“…The results are compared against the data from the grazing incidence tube (GIT) at the NASA Langley Research Center, published by Jones et al [11] in Section 5. These data are the most extensive available for such a configuration and have been widely used to benchmark the use of flow impedance boundary conditions in numerical schemes [12,13,14]. These results are discussed further along with the improved efficiency of the methodology in Section 6, before conclusion are presented in Section 7.…”

Section: Introductionmentioning

confidence: 99%

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A wave expansion method for acoustic propagation in lined flow ducts

O’Reilly

2015

Applied Acoustics

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Acoustic liners are used extensively in engineering applications, particularly in aero-engines and automotive exhaust systems. In this paper, a flow impedance boundary conditions is introduced into the wave expansion method with the aim of providing an efficient methodology for computing the acoustic propagation through a lined duct with flow. For a potential flow, the boundary layer and the lined wall are included in the discretisation scheme by the Myers flow impedance boundary condition. The acoustic propagation through a flow-impedance tube is computed in order to validate the implementation of the impedance boundary condition in this scheme. The results show that this computationally light methodology provides generally good agreement with the experimental data.

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Section: Validation Of the Propagation Methodologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A wave expansion method for acoustic propagation in lined flow ducts

O’Reilly

2015

Applied Acoustics

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“…Other popular impedance models include the Extended Helmholtz Resonator proposed by Rienstra [33], the three-parameter model by Tam and Auriault [36], and broadband impedance models [28]. They differ by the way they are formulated and implemented in the time domain, as well as their ability to represent realistic impedance functions.…”

Section: Impedance Conditionmentioning

confidence: 99%

“…As reported in the literature [28,12,23,30], it is quite common to use additional damping or filtering in the Myers condition to attempt to remove the instability associated with the liner in time-domain simulations (although the details are not always fully described). In principle the filter should not remove any physical instabilities.…”

Section: Use Of Filters and Damping Termsmentioning

confidence: 99%

“…In practice the filter strength has generally been fixed to a large value with the expectation that it should be sufficient for most cases. There is the risk with this approach that the filtering of the Myers condition has an impact on the acoustic field, although some published results indicate that this is not necessarily the case [28,12,23,30] and that accurate acoustic predictions can be obtained with a strong filter.…”

Section: Use Of Filters and Damping Termsmentioning

confidence: 99%

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A full discrete dispersion analysis of time-domain simulations of acoustic liners with flow

Gabard

2014

Journal of Computational Physics

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The effect of flow over an acoustic liner is generally described by the Myers impedance condition. The use of this impedance condition in time-domain numerical simulations has been plagued by stability issues, and various ad hoc techniques based on artificial damping or filtering have been used to stabilise the solution. The theoretical issue leading to the ill-posedness of this impedance condition in the time domain is now well understood. For computational models, some trends have been identified, but no detailed investigation of the cause of the instabilities in numerical simulations has been undertaken to date. This paper presents a dispersion analysis of the complete numerical model, based on finite-difference approximations, for a twodimensional model of a uniform flow above an impedance surface. It provides insight into the properties of the instability in the numerical model and clarifies the parameters that influence its presence. The dispersion analysis is also used to give useful information about the accuracy of the acoustic solution.Comparison between the dispersion analysis and numerical simulations shows that the instability associated with the Myers condition can be identified in the numerical model, but its properties differ significantly from that of the continuous model. The unbounded growth of the instability in the continuous model is not present in the numerical model due to the wavenumber aliasing inherent to numerical approximations. Instead, the numerical instability includes a wavenumber component behaving as an absolute instability. The trend previously reported that the instability is more likely to appear with fine grids is explained. While the instability in the numerical model is heavily dependent on the spatial resolution, it is well resolved in time and is not sensitive to the time step. In addition filtering techniques to stabilise the solutions are considered and it is found that, while they can reduce the instability in some cases, they do not represent a systematic or robust solution in general.

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Highlights of Aeroacoustics Research in the U.S.—1998

Raman

McLaughlin

1999

Journal of Sound and Vibration

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Time-Domain Numerical Simulation of a Flow-Impedance Tube

Cited by 108 publications

References 15 publications

A wave expansion method for acoustic propagation in lined flow ducts

A wave expansion method for acoustic propagation in lined flow ducts

A full discrete dispersion analysis of time-domain simulations of acoustic liners with flow

Highlights of Aeroacoustics Research in the U.S.—1998

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