An acoustic/viscous splitting technique for computational aeroacoustics

Hardin, Jay C.; Pope, D. Stuart

doi:10.1007/bf00311844

Cited by 198 publications

(137 citation statements)

References 5 publications

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“…Likewise, high temperature gradients could induce additional vorticity in the flow through density variations (Zhou & Gore 1998). The incorporation of nonlinear effects in viscous flows has been discussed by Hardin & Pope (1994), who examined pressure fluctuations obtained about the corresponding 'corrected' incompressible flow. Despite this difficulty in separating the effect of modes, there is a clear advantage in isolating the acoustic mode to determine the near-field sound signature and dynamics of the corresponding source mechanisms.…”

Section: S Unnikrishnan and D V Gaitondementioning

confidence: 99%

Acoustic, hydrodynamic and thermal modes in a supersonic cold jet

Nair

Gaitonde

2016

J. Fluid Mech.

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Large-eddy simulation data for a Mach 1.3 round jet are decomposed into acoustic, hydrodynamic and thermal components using Doak's momentum potential theory. The decomposed fields are then analysed to examine the properties of each mode and their dynamics based on the transport equation for the total fluctuating enthalpy. The solenoidal fluctuations highlight hydrodynamic components of the jet and capture the shear layer growth and breakdown process. The acoustic mode exhibits a jittering coherent wavepacket structure in the turbulent region and consequent highly directional downstream radiation. The expected radial decay rates, r for acoustic, are recovered and closely follow the universal radiation spectra in the sideline and downstream directions. The scalogram of the acoustic mode in the near-acoustic-field region is consistent with that of the pressure perturbation signal in the acoustic-frequency range, but effectively removes the hydrodynamic and thermal content. The time-resolved and mean behaviour of terms in the total fluctuating enthalpy equation is analysed in detail. A large-scale intermittent event in the near-acoustic field is shown to be associated with an intrusion of vortices from the shear layer into the core of the jet. Acoustic sources are created when the resulting negative fluctuations in the solenoidal component interact with positive fluctuations in the Coriolis acceleration term. The latter are associated with regions of high vorticity on the inner side of the shear layer. In contrast, sinks result from the interaction of solenoidal momentum fluctuations with positive entropy gradients along entrainment streaks.

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Section: S Unnikrishnan and D V Gaitondementioning

confidence: 99%

Acoustic, hydrodynamic and thermal modes in a supersonic cold jet

Nair

Gaitonde

2016

J. Fluid Mech.

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“…This technique is proposed by Hardin, Pope [6] and improved by Shen and Sørensen [12,13]. It assumes that the compressible flow field at low Mach number can be decomposed into an incompressible flow field and an acoustic field…”

Section: Linearized Euler Equations For Aeroacoustic Simulationmentioning

confidence: 99%

On the Simulation of Aerodynamic Noise With Different Turbulence Models

Huang¹,

Schäfer²

2016

Proceedings of the VII European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS Congress 2016)

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Abstract. This paper investigates the performance of different turbulence models for simulating the aeroacoustic field generated by turbulent flow. The acoustic field is calculated by solving the linearized Euler equations (LEE), while the acoustic source is obtained by solving the incompressible Navier-Stokes equations. Three different turbulence models are adopted for the flow simulation: the large eddy simulation (LES), the delayed detached-eddy simulation (DDES) and unsteady Reynolds Averaged Navier-Stokes equations (URANS). The acoustic sources are calculated on a flow grid and then transferred and interpolated onto an acoustic grid, enabling the acoustic computation of the far field with a reasonable computational cost. We present the acoustic sources calculated using different turbulence models. Furthermore, we compare the sound pressure level (SPL) spectra of different turbulence models with the experimental data. 7599X. Huang, M. Schäfer

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“…For flow situations where no feedback of the acoustics to the flow simulation is necessary, another approach was developed by Hardin and Pope [4], the so called Expansion about Incompressible Flow (EIF). Here, the incompressible equations are solved by any standard incompressible solver.…”

Section: Expansion About Incompressible Flow (Eif)mentioning

confidence: 99%

Calculation of low Mach number acoustics: a comparison of MPV, EIF and linearized Euler equations

Roller¹,

Schwartzkopff²,

Fortenbach³

et al. 2005

ESAIM: M2AN

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Abstract. The calculation of sound generation and propagation in low Mach number flows requires serious reflections on the characteristics of the underlying equations. Although the compressible Euler/Navier-Stokes equations cover all effects, an approximation via standard compressible solvers does not have the ability to represent acoustic waves correctly. Therefore, different methods have been developed to deal with the problem. In this paper, three of them are considered and compared to each other. They are the Multiple Pressure Variables Approach (MPV), the Expansion about Incompressible Flow (EIF) and a coupling method via heterogeneous domain decomposition. In the latter approach, the non-linear Euler equations are used in a domain as small as possible to cover the sound generation, and the locally linearized Euler equations approximated with a high-order scheme are used in a second domain to deal with the sound propagation. Comparisons will be given in construction principles as well as implementational effort and computational costs on actual numerical examples.Mathematics Subject Classification. 41A60, 65M55, 76Q05.

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An acoustic/viscous splitting technique for computational aeroacoustics

Cited by 198 publications

References 5 publications

Acoustic, hydrodynamic and thermal modes in a supersonic cold jet

Acoustic, hydrodynamic and thermal modes in a supersonic cold jet

On the Simulation of Aerodynamic Noise With Different Turbulence Models

Calculation of low Mach number acoustics: a comparison of MPV, EIF and linearized Euler equations

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