Evaluation of the characteristic dimensions for porous sound-absorbing materials

Henry, Michel; Lemarinier, Pavel; Allard, Jean François; Bonardet, J.L.; Gédéon, A.

doi:10.1063/1.359366

Cited by 31 publications

(15 citation statements)

References 10 publications

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“…These macroscopic parameters are of utmost importance to characterize the thermal dissipation mechanisms in sound absorbing materials. 1,10,31 Finally, the PUC approach is presented here as a simple microstructural method that could be used to extract other macroscopic and dynamic acoustical properties from a porous medium, such as the dynamic thermal and viscous permeabilities, directly computed on a three-dimensional reconstructed idealized PUC. 32 FIG.…”

Section: Discussionmentioning

confidence: 99%

“…It is worth mentioning that the studied thermal characteristic lengthcommonly used in acoustics of porous media-is a parameter closely related to the specific surface of the solid porous frame. 10 This article is organized as follows. Section II describes the studied porous media, the experimental setup, and the method of idealized PUC reconstruction.…”

Section: Introductionmentioning

confidence: 99%

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Periodic unit cell reconstruction of porous media: Application to open-cell aluminum foams

Perrot

Panneton

Olny

2007

Journal of Applied Physics

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In this article, the issue of reconstructing an idealized periodic unit cell ͑PUC͒ to represent a porous medium is examined by means of microcomputed tomography ͑ CT͒. Using CT, three-dimensional images of open-cell foam are collected and used to characterize the representative parameters of its cellular morphology. These parameters are used in order to reconstruct the porous medium by means of an idealized PUC: a tetrakaidecahedron with ligaments of triangular cross sections, whose characteristic dimensions have been measured on the CT images. The proposed reconstruction of the idealized PUC is applied to four aluminum foams. The averaged macroscopic properties of the foams ͑open porosity and thermal characteristic length͒ are deduced from their respective PUC model and compared to experimental measurements and literature data. Good correlations are obtained. For each of the foams, this provides a parameterized idealized periodic unit cell on which the partial differential equations governing sound dissipation and propagation in foams can be solved with a view to studying the microphysical basis of the acoustical macrobehavior.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Periodic unit cell reconstruction of porous media: Application to open-cell aluminum foams

Perrot

Panneton

Olny

2007

Journal of Applied Physics

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“…Champoux and Allard 22 and Henry et al 23 reported a slightly different expression for the polytropic exponent n.…”

Section: ͑A6͒mentioning

confidence: 99%

Dispersive surface waves along partially saturated porous media

Chao

Smeulders

Dongen

2006

The Journal of the Acoustical Society of America

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Numerical results for the velocity and attenuation of surface wave modes in fully permeable liquid/ partially saturated porous solid plane interfaces are reported in a broadband of frequencies ͑100 Hz-1 MHz͒. A modified Biot theory of poromechanics is implemented which takes into account the interaction between the gas bubbles and both the liquid and the solid phases of the porous material through acoustic radiation and viscous and thermal dissipation. This model was previously verified by shock wave experiments. In the present paper this formulation is extended to account for grain compressibility. The dependence of the frequency-dependent velocities and attenuation coefficients of the surface modes on the gas saturation is studied. The results show a significant dependence of the velocities and attenuation of the pseudo-Stoneley wave and the pseudo-Rayleigh wave on the liquid saturation in the pores. Maximum values in the attenuation coefficient of the pseudo-Stoneley wave are obtained in the 10-20 kHz range of frequencies. The attenuation value and the characteristic frequency of this maximum depend on the liquid saturation. In the high-frequency limit, a transition is found between the pseudo-Stoneley wave and a true Stoneley mode. This transition occurs at a typical saturation below which the slow compressional wave propagates faster than the pseudo-Stoneley wave.

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“…͑4͒ shall be solved by using the proper boundary condition on the fibers. In the literature [1][2][3][4][5][6][7][8][9][10][11][12] one assumes that the temperature rise on the fibers is zero. But this is not accurate for light commercial glass wool, because the heat capacity of the glass fibers per volume is not infinitely great compared to the heat capacity of the air.…”

Section: General Theorymentioning

confidence: 99%

“…The established way of predicting the acoustical properties of fiber materials is by use of the theory of porous materials, which has been described by many authors. [1][2][3][4][5][6][7][8][9][10][11][12] In this theory, one assumes that the material consists of a matrix with circular pores of small radius. The compressibility of the air in the pores can be computed if one knows the radius of the pores, but for fibrous material it is not obvious how one finds the radius of the pores from the diameters of the fibers and their mean distances.…”

Section: Introductionmentioning

confidence: 99%

Compressibility of air in fibrous materials

Tarnow

1996

The Journal of the Acoustical Society of America

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The dynamic compressibility of air in fibrous materials has been computed for two assumed configurations of fibers which are close to the geometry of real fiber materials. Models with parallel cylinders placed in a regular square lattice and placed randomly are treated. For these models the compressibility is computed approximately from the diameter and mean distances between cylinders. This requires calculation of the air temperature, which is calculated for cylinders in a regular lattice by the Wigner-Seitz cell approximation. In the case of random placement, the calculation is done by a summation over thermal waves from all fibers, and by a self-consistent procedure. Figures of the compressibility in the frequency range 10-100 000 Hz, are given for diameter of the cylinders of 6.8 m, and mean distances between them from 50 to 110 m, which corresponds to glass wool with a density of 40 to 16 kg/m 3 . When the theoretical values for random placement were compared with measurements, it turned out that the random model could not describe the experimental data. However, they could be described accurately by assuming that the fibers have a tendency to form pairs.

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Evaluation of the characteristic dimensions for porous sound-absorbing materials

Cited by 31 publications

References 10 publications

Periodic unit cell reconstruction of porous media: Application to open-cell aluminum foams

Periodic unit cell reconstruction of porous media: Application to open-cell aluminum foams

Dispersive surface waves along partially saturated porous media

Compressibility of air in fibrous materials

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