The acoustic properties of granular materials with pore size distribution close to log-normal

Citation
Kv. Horoshenkov et Mj. Swift, The acoustic properties of granular materials with pore size distribution close to log-normal, J ACOUST SO, 110(5), 2001, pp. 2371-2378
Citations number
22
Categorie Soggetti
Multidisciplinary,"Optics & Acoustics
Journal title
JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA
ISSN journal
00014966 → ACNP
Volume
110
Issue
5
Year of publication
2001
Part
1
Pages
2371 - 2378
Database
ISI
SICI code
0001-4966(200111)110:5<2371:TAPOGM>2.0.ZU;2-C
Abstract
The majority of realistic porous materials are composed of pores of which t he shape is variable and the size of the pores normally obeys a distinctive statistical distribution. Although the variation of pore shape is less imp ortant, the statistical parameters of pore size distribution can have a con siderable effect on the acoustic properties of porous media. This paper dis cusses the application of a simple model for the prediction of the acoustic properties of porous granular media with some assumed pore geometry and po re size distribution close to log-normal. The model is based on the rationa l (Pade) approximation approach [K. V. Horoshenkov, K. Attenborough, and S. N. Chandler-Wilde, J. Acoust. Soc. Am. 104, 1198-1209 (1998)] which has be en developed for some simple pore geometries. It is shown that the experime ntally determined pore size distribution for a representative range of gran ular materials is often close to log-normal. This assumption enables accura te predictions of the acoustic performance of these materials using the pre sented model. The water suction method is proposed to determine the paramet ers of the log-normal distribution, which are the mean pore size, [phi], an d its standard deviation, sigma. This method is nonacoustic, modelless and well-adapted to acoustic materials and, unlike the BET method [S. Brunauer, P. H. Emmett, and E. Teller, J. Am. Chem. Soc. 60, 309-319 (1938)], is eas y to reproduce in any basic acoustic laboratory requiring no expensive part s or chemicals. The proposed Pade approximation is based entirely on four m easurable nonacoustic parameters, the porosity, Ohm, flow resistivity, R-b, tortuosity, q(2) and the standard deviation of the pore size, sigma. The m ethod is successfully tested on a representative selection of consolidated and nonconsolidated porous granular materials. (C) 2001 Acoustical Society of America.