Separation of viscothermal losses and scattering in ultrasonic characterization of porous media

Acoustic behaviour of high pressure air-filled porous media

“…The Young's modulus value measured at 100 kHz is higher than the quasi-static values, which is in agreement with the evolution of this parameter at low frequency [8]. However, such values of E and g are obtained in the pressure range [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] bars for a temperature which is not constant all over this pressure range (it varies more than 1°C for pressure greater than 15 bars). Secondly, such a fit was possible for a value of m p equal to 0.47.…”

“…11 presents, for foam M1, minimization for the 2 sets of the measurements (stemmed from measurements at 23 and 24°C seen in Fig. 7 (the second and third cuves from the bottom of the figure)) for pressure in the range [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] bars.…”

“…With the densification of the saturating fluid, leading to a better coupling between transducers and fluid, and a decrease of viscothermal skin depths, this method allows a better transmission through media. Thus, it permits to characterize highly absorbant or damping porous media, even in the presence of weak scattering [12].…”

“…In order to characterize the highly damping materials, a new experimental set-up was developed to realize measurements for higher static pressures included in the range [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] bars. In this high pressure range, the behaviour of n 2 r and j ln jTj differs from the equivalent fluid model one, and is highly sensitive to temperature.…”

Nonlinear Biot waves in porous media with application to unconsolidated granular media

“…26 For shorter wavelengths, becoming of the order of the bead diameter, scattering occurs and its modeling for such close scatterers is a hard task even if the geometry is well-known. 27 In water, owing to the lower acoustic energy dissipation than in air, several pioneering experiments have been carried out on the acoustic energy diffusion process and showed that most of the energy transports through water and that the associated waves are multiply scattered by the glass beads. 28 There are only few experiments where both waves in the fluid and in the bead structure have been shown to play a role and to couple.…”