Ultrasonic wave propagation in porous media: determination of acoustic parameters and high frequency limit of the classical models.
Results on the ultrasonic wave propagation in porous materials are presented with emphasis on the measurement of acoustic parameters and on the discrepancy between experimental results and theoretical predictions for the attenuation at high frequencies. This discrepancy can be observed in Biomedical Engineering where the propagation in different sorts of bones is studied as well as in the fields of Geophysics and Material Science. In the present study, the slow wave propagation in polyurethane foams saturated by different gases is investigated in a frequency range of [70-800 kHz]. Methods are presented to determine the tortuosity and the viscous and thermal characteristic lengths. The experimental results, obtained using standard ultrasonic and vacuum equipments, show that an excess attenuation occurs when the wavelength is not sufficiently large compared to the lateral dimensions of the fibers. This effect constitutes a limit of the classical models of equivalent phases. It is evaluated with the help of a model of ultrasonic scattering. A numerical simulation of osteoporosis using Biot's model is also presented.
Leclaire
P
P
Departement Natuurkunde, Katholieke Universiteit Leuven, Belgium.
Kelders
L
L
Lauriks
W
W
Glorieux
C
C
Thoen
J
J
D000162:Acoustics; D001698:Biomedical Engineering; D001842:Bone and Bones / Q000000981:diagnostic imaging* / Q000502:physiology; D006801:Humans; D008962:Models, Theoretical; D010024:Osteoporosis / Q000000981:diagnostic imaging; D016062:Porosity; D014465:Ultrasonics; D014463:Ultrasonography