Conservative source term interpolation for hybrid aeroacoustic computations

Schoder, Stefan; Junger, Clemens; Weitz, Michael

doi:10.2514/6.2019-2538

Cited by 10 publications

(13 citation statements)

References 5 publications

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“…The aeroacoustic sound generation and acoustic wave propagation is described by the perturbed convective wave equation (PCWE) (Kaltenbacher et al, 2016 ), which is solved via the finite element solver CFS++ (Schoder et al, 2020 ). To compute the acoustic source term for the PCWE, the incompressible pressure field from the CFD is transferred onto the CAA mesh by a conservative interpolation scheme based on a cut cell algorithm (Schoder et al, 2019 , 2020 ). The acoustic source term is then computed on the CAA grid as the partial time derivative of the incompressible pressure.…”

Section: Methods: Hybrid Aeroacoustic Numerical Larynx Model— mentioning

confidence: 99%

3D-FV-FE Aeroacoustic Larynx Model for Investigation of Functional Based Voice Disorders

et al. 2021

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For the clinical analysis of underlying mechanisms of voice disorders, we developed a numerical aeroacoustic larynx model, called simVoice, that mimics commonly observed functional laryngeal disorders as glottal insufficiency and vibrational left-right asymmetries. The model is a combination of the Finite Volume (FV) CFD solver Star-CCM+ and the Finite Element (FE) aeroacoustic solver CFS++. simVoice models turbulence using Large Eddy Simulations (LES) and the acoustic wave propagation with the perturbed convective wave equation (PCWE). Its geometry corresponds to a simplified larynx and a vocal tract model representing the vowel /a/. The oscillations of the vocal folds are externally driven. In total, 10 configurations with different degrees of functional-based disorders were simulated and analyzed. The energy transfer between the glottal airflow and the vocal folds decreases with an increasing glottal insufficiency and potentially reflects the higher effort during speech for patients being concerned. This loss of energy transfer may also have an essential influence on the quality of the sound signal as expressed by decreasing sound pressure level (SPL), Cepstral Peak Prominence (CPP), and Vocal Efficiency (VE). Asymmetry in the vocal fold oscillations also reduces the quality of the sound signal. However, simVoice confirmed previous clinical and experimental observations that a high level of glottal insufficiency worsens the acoustic signal quality more than oscillatory left-right asymmetry. Both symptoms in combination will further reduce the quality of the sound signal. In summary, simVoice allows for detailed analysis of the origins of disordered voice production and hence fosters the further understanding of laryngeal physiology, including occurring dependencies. A current walltime of 10 h/cycle is, with a prospective increase in computing power, auspicious for a future clinical use of simVoice.

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Section: Methods: Hybrid Aeroacoustic Numerical Larynx Model— mentioning

confidence: 99%

3D-FV-FE Aeroacoustic Larynx Model for Investigation of Functional Based Voice Disorders

et al. 2021

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“…Since in addition to the wave propagation resolution, acoustic source terms must be resolved. As shown in [9], all sources in the dimension of the mesh size can be resolved, properly. So the first guess is to discretize this region with the same resolution as the propagation region and to refine where small scale source terms are assumed.…”

Section: Mesh Discretizationmentioning

confidence: 99%

“…Considering low pressure axial fans, main contributions to the current state of the art have been made by several authors [4][5][6][7][8] but are not limited to them. In this contribution, we aim to present the whole aeroacoustic simulation process for a successful computation of the flow and acoustic signature of an axial fan: (1) meshing approach for the computational fluid dynamics (CFD) simulation; (2) turbulence modeling; (3) CFD convergence study; (4) evaluation of the most significant flow results for a subsequent acoustic simulation; (5) computational domain and meshing for the simulation of the acoustic field; (6) acoustic source term evaluation, possible truncation and interpolation [9] from the CFD to the acoustic grid; (7) acoustic field computation and the analysis of its most relevant physical quantities. For the aeroacoustic modeling, we investigate two sound propagation models.…”

Section: Introductionmentioning

confidence: 99%

Computational aeroacoustics of the EAA benchmark case of an axial fan

Schoder

Junger

2020

Acta Acust.

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This contribution benchmarks the aeroacoustic workflow of the perturbed convective wave equation and the Ffowcs Williams and Hawkings analogy in Farassat’s 1A version for a low-pressure axial fan. Thereby, we focus on the turbulence modeling of the flow simulation and mesh convergence concerning the complete aeroacoustic workflow. During the validation, good agreement has been found with the efficiency, the wall pressure sensor signals, and the mean velocity profiles in the duct. The analysis of the source term structures shows a strong correlation to the sound pressure spectrum. Finally, both acoustic sound propagation models are compared to the measured sound field data.

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“…PCWE has been applied to HVAC systems 181,182 extensively. The prediction of fan noise 42,60,183,184 as well as human phonation 185,186 suits the assumptions of this equation.…”

Section: Perturbed Convective Wave Equation (Pcwe)mentioning

confidence: 75%

“…This difference might be due to the limited source interpolation. 183 Both compressible and incompressible flow simulation have been investigated with a minor difference, as expected at this low Mach number (Mach 0.05). The results show good agreement, at least for the velocity-based simulations.…”

Section: Comparison Of the Formulationsmentioning

confidence: 99%

Hybrid Aeroacoustic Computations: State of Art and New Achievements

Schoder

2019

J. Theor. Comp. Acout.

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This paper collects the state of the art and the tremendous progress that has been made in hybrid modeling of aeroacoustic sound. Hybrid modeling is defined such that flow and acoustics are modeled separate and connected by an aeroacoustic model. The contributions will be classified with respect to the aeroacoustic models being developed, covering Lighthill’s analogy, Ffowcs Williams and Hawkings, vortex sound, linearized Euler equations (LEE), and different perturbation equations modeling flow induced sound. Within each topic, specific applications, such as jet noise, aircraft noise, ground mobility, noise, fan noise and human phonation, are covered. We focus on the accomplishments and provide the authors’ contribution to aeroacoustic research. Eventually, a concise summary of the different methods and their capabilities is included.

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Conservative source term interpolation for hybrid aeroacoustic computations

Cited by 10 publications

References 5 publications

3D-FV-FE Aeroacoustic Larynx Model for Investigation of Functional Based Voice Disorders

3D-FV-FE Aeroacoustic Larynx Model for Investigation of Functional Based Voice Disorders

Computational aeroacoustics of the EAA benchmark case of an axial fan

Hybrid Aeroacoustic Computations: State of Art and New Achievements

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