The Fast Field Program (FFP). A second tutorial: Application to long range sound propagation in the atmosphere

West, M.; Sack, R. A.; Walkden, F.

doi:10.1016/0003-682x(91)90058-m

Cited by 28 publications

(10 citation statements)

References 15 publications

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“…[1][2][3][4] In addition, some publications have dealt with theoretical verification and modification of models of this type and comparison with other types of models. [5][6][7][8][9] FFP models have proven to give satisfactory results for a variety of propagation conditions and for sources of different nature. Lowfrequency sound propagation has been studied by some authors, e.g., Robertson et al ͑1995͒ 10 who presented parabolic approximation predictions of pure-tone frequencies from 40 to 160 Hz out to 3 km and compared with experimental data.…”

Section: Introductionmentioning

confidence: 95%

Effects of strong sound velocity gradients on propagation of low-frequency impulse sound: Comparison of fast field program predictions and experimental data

Hole

Lunde

Gjessing³

1997

The Journal of the Acoustical Society of America

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As part of a large outdoor sound propagation experiment series, propagation of low-frequency impluse sound at ranges from 100 to 1400 m was studied at Haslemoen, Norway in February 1995. Sound sources were charges of 1 and 8 kg C4 explosives. Experiments were carried out in both a uniform forest and above a flat and uniform open field. Extensive meteorological measurements were carried out. Both automatic weather stations mounted in permanent towers and a tethered balloon were employed. The measurements resulted in a manifold set of sound velocity profiles. Occasionally, profiles were pure downwind or upwind, but mostly they were complex, often with large vertical gradients. One conclusion is that one should not uncritically use simple profile parameterizations, e.g., logarithmic, in sound propagation models. A fast field program (FFP), CAPROS, handles the complex sound-speed profiles well, predicting propagation of sound at 8, 16, 32.5, and 63 Hz. In this model, ground is considered a viscoelastic medium. At 63 Hz, the forest seems to cause an excess attenuation. At the lower frequencies, distinct effects of forest are not observed. There is no evidence that FFP predictions are less accurate in periods with high turbulence levels, which is here characterized with dynamical instability. However, variability of meteorological profiles causes predictions to be less accurate. This investigation suggests that it is sufficient to sample atmospheric variables up to 300 m above ground to predict sound propagation at the ranges studied here.

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Section: Introductionmentioning

confidence: 95%

Effects of strong sound velocity gradients on propagation of low-frequency impulse sound: Comparison of fast field program predictions and experimental data

Hole

Lunde

Gjessing³

1997

The Journal of the Acoustical Society of America

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“…This is the case for approaches based on the fast field program (FPP) and parabolic equations (PE), which have been used extensively to study acoustic propagation. [6][7][8] Such approaches provide approximate solutions to the wave equation, and suffer from limitations due both to the resolution technique, e.g., FFP is limited to horizontally homogeneous problems while PE methods have angular limitations, and to the wave equation itself, in particular its linearity. It should be noted that recently developed non-linear parabolic equations 9 alleviate the latter problem.…”

Section: Introductionmentioning

confidence: 99%

A study of infrasound propagation based on high-order finite difference solutions of the Navier-Stokes equations

Marsden

Bogey

Bailly

2014

The Journal of the Acoustical Society of America

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The feasibility of using numerical simulation of fluid dynamics equations for the detailed description of long-range infrasound propagation in the atmosphere is investigated. The two dimensional (2D) Navier Stokes equations are solved via high fidelity spatial finite differences and Runge-Kutta time integration, coupled with a shock-capturing filter procedure allowing large amplitudes to be studied. The accuracy of acoustic prediction over long distances with this approach is first assessed in the linear regime thanks to two test cases featuring an acoustic source placed above a reflective ground in a homogeneous and weakly inhomogeneous medium, solved for a range of grid resolutions. An atmospheric model which can account for realistic features affecting acoustic propagation is then described. A 2D study of the effect of source amplitude on signals recorded at ground level at varying distances from the source is carried out. Modifications both in terms of waveforms and arrival times are described.

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“…Originally developed for applications in underwater acoustics, several computational methods for modelling acoustic environments have been adapted and successfully applied (Gilbert & Di, 1993;Salomons, 2001;West, Gilbert, & Sack, 1992;West, Sack, & Walden, 1991) to atmospheric acoustic problems over several years. The fast-field program (FFP) (West et al, 1991), Crank-Nicholson parabolic equation (CNPE) (West et al, 1992), and Green's function parabolic equation (GFPE) (Gilbert & Di, 1993) are among the most extensively studied atmospheric acoustic models.…”

Section: Introductionmentioning

confidence: 99%

“…The fast-field program (FFP) (West et al, 1991), Crank-Nicholson parabolic equation (CNPE) (West et al, 1992), and Green's function parabolic equation (GFPE) (Gilbert & Di, 1993) are among the most extensively studied atmospheric acoustic models. Using any of these techniques, the calculated TL values are generally accepted as reliable (Attenborough et al, 1995), but the computational resources required to compute these TL values is highly variable.…”

Section: Introductionmentioning

confidence: 99%

Environmentally adaptive acoustic transmission loss prediction in turbulent and nonturbulent atmospheres

2007

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An environmentally adaptive system for prediction of acoustic transmission loss (TL) in the atmosphere is developed in this paper. This system uses several back propagation neural network predictors, each corresponding to a specific environmental condition. The outputs of the expert predictors are combined using a fuzzy confidence measure and a nonlinear fusion system. Using this prediction methodology the computational intractability of traditional acoustic model-based approaches is eliminated. The proposed TL prediction system is tested on two synthetic acoustic data sets for a wide range of geometrical, source and environmental conditions including both nonturbulent and turbulent atmospheres. Test results of the system showed root mean square (RMS) errors of 1.84 dB for the nonturbulent and 1.36 dB for the turbulent conditions, respectively, which are acceptable levels for near real-time performance. Additionally, the environmentally adaptive system demonstrated improved TL prediction accuracy at high frequencies and large values of horizontal separation between source and receiver.

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The Fast Field Program (FFP). A second tutorial: Application to long range sound propagation in the atmosphere

Cited by 28 publications

References 15 publications

Effects of strong sound velocity gradients on propagation of low-frequency impulse sound: Comparison of fast field program predictions and experimental data

Effects of strong sound velocity gradients on propagation of low-frequency impulse sound: Comparison of fast field program predictions and experimental data

A study of infrasound propagation based on high-order finite difference solutions of the Navier-Stokes equations

Environmentally adaptive acoustic transmission loss prediction in turbulent and nonturbulent atmospheres

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