Drag forces of porous-medium acoustics

Pride, Steven R.; Morgan, Frank Dale; Gangi, Afshin

doi:10.1103/physrevb.47.4964

Cited by 212 publications

(173 citation statements)

References 12 publications

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“…In channels with fractal pore-fluid surfaces A fs , the classical scaling in (20) does not hold anymore because Λ ≡ 2V f /A fs → 0, and consequently M → ∞. If the yardstick of our fractal analysis is represented by the thickness of the boundary layer, δ, we expect that the measure of the boundary layer itself will roughly follow the scaling of the fractal surface.…”

Section: Fractal Wall Surfacesmentioning

confidence: 99%

“…Despite the great variability of the pore microgeometries considered in the literature [15][16][17][18] , it is generally found, both experimentally and numerically, that the normalized dynamic permeabilityk(ω) matches reasonably well a scaling function 19,20 which depends on a characteristic frequency ω c and a similarity parameter, M . Remarkably, M is usually found to be almost configuration independent and close to unity, as long as the pore surface is locally smooth 19,21,22 .…”

Section: Introductionmentioning

confidence: 99%

“…The universal scaling can be modeled in terms of a function, F (ω), which is defined in such a way to satisfy both the low-and high-frequency theoretical limits, and to be exact in the limiting case of 2D slit flow. The expression for the dynamic permeability reads thus 19,20 …”

Section: B Macroscopic Flow Equationsmentioning

confidence: 99%

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Frequency-dependent viscous flow in channels with fractal rough surfaces

Cortis

Berryman

2010

Physics of Fluids

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The viscous dynamic permeability of some fractal-like channels is studied. For our particular class of geometries, the ratio of the pore surface area-to-volume tends to ∞ (but has a finite cutoff), and the universal scaling of the dynamic permeability, k(ω), needs modification. We performed accurate numerical computations of k(ω) for channels characterized by deterministic fractal wall surfaces, for a broad range

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Section: Fractal Wall Surfacesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Frequency-dependent viscous flow in channels with fractal rough surfaces

Cortis

Berryman

2010

Physics of Fluids

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“…The soobtained solutions are only the best fitted parameters for the model under consideration. It should be mentioned that both the Johnson et al and Lafarge et al model were improved 26,27 in order to match more exactly the frequency behavior of K eq and q eq introducing more intrinsic geometrical parameters. However, due to the actual difficulties to measure or determine these parameters, they are not studied in this paper.…”

Section: -3mentioning

confidence: 99%

Effect of the microstructure closed pore content on the acoustic behavior of polyurethane foams

Doutres¹,

Atalla²,

Dong³

2011

Journal of Applied Physics

129

134

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The present paper proposes to investigate the links between the microstructure of polyurethane foams and their sound absorbing efficiency, and more specifically the effect of membranes closing the cells. This study is based on the complete characterization of 15 polyurethane foam with various cell sizes and reticulation rates (i.e., open pore content): (i) characterization of the microstructure properties (cell size C s , strut thickness t, reticulation rate R w …) from SEM pictures, (ii) characterization of nonacoustic parameters (porosity U, airflow resistivity r, tortuosity a 1 …) from direct and indirect methods. Existing analytical links between microstructure properties and nonacoustic parameters are first applied to fully reticulated materials. Then, they are improved empirically to account for the presence of the closed pore content. The proposed expressions associated to the Johnson-Champoux-Allard porous model allow a good estimation of the sound absorbing behavior of all polyurethane foams, fully reticulated or not. This paper also demonstrates the important effect of the presence of cell membranes: increase of the airflow resistivity, tortuosity, and the ratio between the thermal and viscous characteristic lengths while decreasing these two characteristic lengths. Thus, the sound absorption efficiency at low frequencies is improved but can be worsened in some higher frequency bands.

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“…1,2 Alternatively, in a search for a theoretical understanding, one may try to better understand the mathematical and physical basis of the macroscopic equations governing acoustic dissipation phenomena. [3][4][5][6][7] Finally, numerical studies based on simulations can be considered. [8][9][10][11][12][13] Each of these ways of considering these questions has advantages and disadvantages.…”

Section: Introductionmentioning

confidence: 99%

Computation of the dynamic thermal dissipation properties of porous media by Brownian motion simulation: Application to an open-cell aluminum foam

Perrot

Panneton

Olny³

2007

Journal of Applied Physics

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To cite this version:C. Perrot, R. Panneton, X. Olny. This paper reports simulation results of frequency dependent heat conduction through three-dimensional reconstructed unit cells of an open-cell aluminum foam under acoustic excitations. First, a three-dimensional random walk based algorithm is proposed to calculate the dynamic thermal permeability or dynamic bulk modulus of periodic complex porous geometries. Second, the error and convergence of the implemented calculation algorithm are quantified in terms of the random walk population, normalized trapping distance, and type of geometry. Finally, the algorithm is applied to the calculation of the dynamic bulk modulus of an aluminum foam and compared to laboratory measurements. Good agreement is obtained between simulations and measurements.

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Drag forces of porous-medium acoustics

Cited by 212 publications

References 12 publications

Frequency-dependent viscous flow in channels with fractal rough surfaces

Frequency-dependent viscous flow in channels with fractal rough surfaces

Effect of the microstructure closed pore content on the acoustic behavior of polyurethane foams

Computation of the dynamic thermal dissipation properties of porous media by Brownian motion simulation: Application to an open-cell aluminum foam

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