Quasi-Wavelet Model of Von Kármán Spectrum of Turbulent Velocity Fluctuations

Goedecke, G. H.; Ostashev, Vladimir E.; Wilson, D. Keith; Auvermann, Harry J.

doi:10.1023/b:boun.0000020158.10053.ab

Cited by 30 publications

(32 citation statements)

References 40 publications

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“…At this high-Reynolds number, a relatively broad spectrum of pressure fluctuations is generated with flow over the upstream circular cylinder, in contrast to a low-Reynolds number flow, where only very tonal pressure fluctuations, related to the von Karman vortex shedding frequency, are generated. The shape of the broadband spectrum of the unscreened case (to be shown shortly) is very similar to those of wind noise in the literature [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] that follow the À5/3-frequency power decay of the spectrum of atmospheric turbulent pressure.…”

Section: Resultssupporting

confidence: 63%

“…Broadband pressure fluctuations are generated by placing a solid circular cylinder upstream of the microphone, which produces wake turbulence corresponding to a cylinder-diameter based Reynolds number of 5000. Although more realistic atmospheric turbulence could be incorporated in future studies using other methods such as the quasi-wavelet fields, 16,17 such methods may require further improvements if they are to be adapted for numerical simulation. Nevertheless, this study provides a significant step in solving the numerically and physically complex problem of turbulent WNR.…”

Section: Introductionmentioning

confidence: 99%

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A computational study of the effect of windscreen shape and flow resistivity on turbulent wind noise reduction

Zheng

Wilson

2011

The Journal of the Acoustical Society of America

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In this paper, numerical simulations are used to study the turbulent wind noise reduction effect of microphone windscreens with varying shapes and flow resistivities. Typical windscreen shapes consisting of circular, elliptical, and rectangular cylinders are investigated. A turbulent environment is generated by placing a solid circular cylinder upstream of the microphone. An immersed-boundary method with a fifth-order weighted essentially non-oscillatory scheme is implemented to enhance the simulation accuracy for high-Reynolds number flow around the solid cylinder as well as at the interface between the open air and the porous material comprising the windscreen. The Navier-Stokes equations for incompressible flow are solved in the open air. For the flow inside the porous material, a modified form of the Zwikker-Kosten equation is solved. The results show that, on average, the circular and horizontal ellipse windscreens have similar overall wind noise reduction performance, while the horizontal ellipse windscreen with medium flow resistivity provides the most effective wind noise reduction among all the considered cases. The vertical ellipse windscreen with high flow resistivity, in particular, increases the wind noise because of increased self-generation of turbulence.

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Section: Resultssupporting

confidence: 63%

Section: Introductionmentioning

confidence: 99%

A computational study of the effect of windscreen shape and flow resistivity on turbulent wind noise reduction

Zheng

Wilson

2011

The Journal of the Acoustical Society of America

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“…More realistic atmospheric turbulence could be incorporated in future studies using other methods such as the quasi-wavelet method. 16,17 The Reynolds number for the cases presented here is 500, which approximately corresponds to a windscreen with a diameter of 0. . In the simulation here, the grid size is 0.025 in both the x and y directions, and the time step is 0.002, which satisfies the stability condition for the computational scheme.…”

Section: Resultsmentioning

confidence: 99%

Simulation of Turbulent Wind Noise Reduction by Porous Windscreens Using High-Order Schemes

Zheng

Wilson

2010

J. Comp. Acous.

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The purpose of the study is to investigate the wind noise reduction provided by microphone windscreens at different frequencies of the impinging turbulence. The windscreen is assumed to be a cylindrically shaped porous medium. This paper uses a high-order scheme to improve the accuracy at the interface between air and porous medium. The computational scheme is based on a modified immersed-boundary method with distributed forcing terms. The simulation results show that, for low-frequency turbulence, the windscreens with low flow resistivity are more effective in noise reduction, while for high-frequency turbulence, the windscreens with high flow resistivity are more effective.

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“…(5) in Ref. [15]. After some manipulation of that equation, we obtain the 1D spectrum of temperature uctuations, which appears in Eq.…”

Section: Relative Contributions To the Effec-tive Spectrummentioning

confidence: 99%

“…Equation (2a) in Ref. [15] presents the realistic, height-dependent, von Kármán energy spectrum of turbulence. Using that equation, we obtain the 1D spectrum of velocity uctuations, which appears in Eq.…”

Section: Relative Contributions To the Effec-tive Spectrummentioning

confidence: 99%

Waveguide sound propagation in a turbulent atmosphere above randomly rough ground

Ostashev

Wilson

Vecherin

2012

Proceedings of Meetings on Acoustics

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Quasi-Wavelet Model of Von Kármán Spectrum of Turbulent Velocity Fluctuations

Cited by 30 publications

References 40 publications

A computational study of the effect of windscreen shape and flow resistivity on turbulent wind noise reduction

A computational study of the effect of windscreen shape and flow resistivity on turbulent wind noise reduction

Simulation of Turbulent Wind Noise Reduction by Porous Windscreens Using High-Order Schemes

Waveguide sound propagation in a turbulent atmosphere above randomly rough ground

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