Acoustic absorption of solid foams with thin membranes

Gaulon, Camille; Pierre, Juliette; Derec, Caroline; Jaouen, Luc; Bécot, François‐Xavier; Chevillotte, Fabien; Elias, Florence; Drenckhan, Wiebke; Leroy, Valentin

doi:10.1063/1.5025407

Cited by 21 publications

(19 citation statements)

References 23 publications

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“…The eects of membrane on acoustical properties are now the subject of active research [3,811]. It has been shown that closed membranes can increase the eective density of foam [8] and therefore, in agreement with the work of Jonhson et al [1], the foam tortuosity α ∞ [10]. Moreover, closed membranes imply some percolation eects at the mesoscale which can drastically reduce the foam permeability K as shown in [9].…”

Section: Introductionmentioning

confidence: 81%

“…This is certainly not true if the tortuosity is much larger than one. For example, in the case of porous media with soft and/or lightweight frame, sound propagation through uid can induce frame resonance at specic frequencies as observed in [8]. It should be possible in the future to see a comparison between the predictions of the current model and the results from direct experiments using alternative techniques, such as (i) electrical conductivity measurements [4,29], (ii) superuid acoustics (He II) taking advantage of the fact that the acoustics of He II can become identical with the acoustics of an ideal uid [29,30], or (iii) ultrasonic measurements of velocity dispersion in porous media saturated by various uids [31].…”

Section: Discussionmentioning

confidence: 99%

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Electrical conductivity and tortuosity of solid foam: Effect of pore connections

2019

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Numerical and analytical methods at both micro-and mesoscales are used to study how the electrical resistivity and the high frequency tortuosity of solid foam are modied by the presence of membranes that partially or totally close the cell windows connecting neighbor pores. Finite element method (FEM) simulations are performed on two pores connected by a single-holed membrane and on well-ordered Kelvin foam. For two pores connected by a single-holed membrane, we show that the equation for pore access resistance obtained by Sahu and Zwolak (Phys. Rev. E 98, 012404, 2018) can predict, after a few modications, the electrical resistivity at the membrane scale for a large range of membrane apertures. In the second part, considering these analytical results, we build a pore-network model by using two kinds of conductances at the pore scale -inter-pore conductance and intra-pore conductance. Local inter-pore resistances govern foam electrical conductivity at small membrane aperture size, but when the membrane aperture has the same order of magnitude as the pore size, the intra-pore resistances are no longer negligible. An important success of this pore-network model is that it can be used to study the eects of percolation on the foam electrical conductivity by using pore-network simulations on larger samples containing a few thousands of pores and having dierent proportions of closed membrane randomly distributed over the sample.The tortuosity is found to be drastically larger than one in foam containing membranes with small apertures or a signicant fraction of closed membranes.

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Section: Introductionmentioning

confidence: 81%

Section: Discussionmentioning

confidence: 99%

Electrical conductivity and tortuosity of solid foam: Effect of pore connections

2019

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“…Connected to the use of polymerized emulsions or foams, an important axis of research is indeed also to investigate the links between liquid and solid foams, and how a better understanding of sound propagation in liquid foams could help to design better solid ones. For instance, Gaulon et al studied two types of highly controlled polyurethane foams [73]: classical open-cell ones versus membrane foams, in which thin polyurethane membranes were preserved during solidification. Interestingly, the latter presented better absorption abilities, indicating that membranes could be an asset for sound absorption [73].…”

Section: Perspectivesmentioning

confidence: 99%

“…For instance, Gaulon et al studied two types of highly controlled polyurethane foams [73]: classical open-cell ones versus membrane foams, in which thin polyurethane membranes were preserved during solidification. Interestingly, the latter presented better absorption abilities, indicating that membranes could be an asset for sound absorption [73].…”

Section: Perspectivesmentioning

confidence: 99%

The Acoustics of Liquid Foams

Elias

Crassous

Derec

et al. 2020

Current Opinion in Colloid & Interface Science

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Beside other transport properties of liquid foams, like the optical or electrical ones, the acoustics of liquid foams reveals a great complexity and non-trivial features. Here we present a review of recent experimental and theoretical results on how a sound wave interacts with either a macroscopic foam sample or with its isolated building blocks (films and Plateau borders). The analysis of the literature allows us to determine what is now well understood, what could be measured in foams by acoustics, and what are the remaining issues and perspectives in this research field.

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“…Recent years have witnessed the continuous and robust development of acoustic metamaterials, which are defined as man-made structures of flexible and even novel acoustic effective properties [ 1 , 2 ]. By using subwavelength structures as units, acoustic metamaterials can realise many extraordinary phenomena such as negative refraction, inverse Doppler effect, cloaking, slab focusing, deep-subwavelength imaging, and super absorption [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ]. More recently, acoustic metasurfaces, metamaterials of reduced dimension, have attracted much research efforts owing to their ultra-thin thickness.…”

Section: Introductionmentioning

confidence: 99%

Tunable Acoustic Metasurface with High-Q Spectrum Splitting

et al. 2018

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We propose a tunable acoustic metasurface using a nested structure as the microunit, which is constituted by two distinct resonators. Thanks to the coupling resonance for the microunit and by simply adjusting the rotation angle of the inner split cavity, this nested structure provides nearly 2π phase shift. The full-wave simulations demonstrate that the constructed metasurface can be tuned to reflect incident sound waves to different directions in the operation frequency region with a very narrow bandwidth, which is a key functionality for many applications such as filtering and imaging. Meanwhile, the reflected sound waves out of the operation frequency region always remain unchanged. As a result, a high Q-factor spectrum splitting can be realised. The presented metasurface is of importance to develop many metamaterial-based devices, such as tunable acoustic cloaks and acoustic switching devices.

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Acoustic absorption of solid foams with thin membranes

Cited by 21 publications

References 23 publications

Electrical conductivity and tortuosity of solid foam: Effect of pore connections

Electrical conductivity and tortuosity of solid foam: Effect of pore connections

The Acoustics of Liquid Foams

Tunable Acoustic Metasurface with High-Q Spectrum Splitting

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