Time-domain calculations of sound interactions with outdoor ground surfaces

Wilson, D. Keith; Ostashev, Vladimir E.; Collier, Sandra L.; Symons, Neill P.; Aldridge, David F.; Marlin, David H.

doi:10.1016/j.apacoust.2005.10.004

Cited by 41 publications

(39 citation statements)

References 18 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: 64%

“…The resulting momentum equation for air flow inside the windscreen is the ZK equation, 11 which is the low-frequency limit of more general forms of porous media equations. 19 In addition, incompressibility is assumed for flow inside the porous medium. The convection and diffusion terms are neglected in the original ZK equation because the velocity is low in the porous medium.…”

Section: Formulation and Solution Schemesmentioning

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: 64%

Section: Formulation and Solution Schemesmentioning

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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“…Only when there is interest in predicting the attenuation inside the porous medium at high sound frequencies and low flow resistivities, adaptions should be made as presented in [21]. Note, however, that the UWVF model is not restricted to a particular porous model, and other models can be implemented without additional difficulties.…”

Section: Equations For Sound Propagation In Porous Mediamentioning

confidence: 99%

“…The porosity, structure factor and flow resistivity of the barrier are chosen as 0.4, 1.35 and 50k Pa·s/m 2 , respectively. Although no particular material is aimed at, such a set of parameters could be representative for uncompacted earth [26,21]. In the UWVF method, the largest allowed mesh size of 0.68 m is used, which is twice the wave length which equals 0.34 m when using a speed of sound of 340 m/s.…”

Section: Sound Propagation Near a Porous Barriermentioning

confidence: 99%

Estimating the Effect of Semi-Transparent Low-Height Road Traffic Noise Barriers with Ultra Weak Variational Formulation

Ding¹,

Renterghem²,

Botteldooren³

2011

Acta Acustica united with Acustica

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Abstract:The ultra weak variational formulation (UWVF) approach is used to study the effect of semi-transparent road traffic noise barriers of limited height. This numerical method is extended to simulate sound propagation through a porous medium, based on the Zwicker and Kosten phenomenological porous rigid-frame model. An efficient approach to calculate noise levels in multi-lane road traffic noise situations is presented. The UWVF method was validated successfully by comparison with finite-difference time-domain (FDTD) calculations, for the case of sound propagation near a porous, low-height, and complex shaped noise barrier, and for sound propagation above porous ground in a refracting atmosphere. An assessment is made of the shielding of various porous low-height noise barriers for people on the pavement along the road. Porous barriers were shown to improve noise shielding when compared to geometrically identical rigid noise barriers.

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“…The air flow inside the windscreen is modeled with the ZK equation, 3 which is the low-frequency limit of more general forms of porous media equations. 11 In addition, incompressibility is assumed for flow inside the porous medium. The governing equations for airflow inside the windscreen are expressed in Eq.…”

Section: Formulation and Numerical Schemesmentioning

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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Time-domain calculations of sound interactions with outdoor ground surfaces

Cited by 41 publications

References 18 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

Estimating the Effect of Semi-Transparent Low-Height Road Traffic Noise Barriers with Ultra Weak Variational Formulation

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

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