Ultrasonic waves in saturated porous materials. Discussion of modeling and experimental results

Models and experimental results obtained for ultrasonic waves in saturated porous materials are analyzed in order to assess the capability of the models to describe basie features of attenuation and dispersion of the waves. The physical mechanisms taken into account are: macroscopic relative motion of phases, micro-inhomogeneity of pore fluid velocity, intergranular friction, and micro-scattering. The role of macroscopic relative motion is studied basing on the results for dry and saturated materials as well as by comparison between wave characteristics for different parameters describing viscous and inertial interaction of the phases. The influence of micro-inhomogeneity of pore fluid velocity is tested throughout the history dependence of interaction force. The theoretical results that incorporate the intergranular friction resulting in complex bulk modulus of dry skeleton are compared with the experimental results for loose and sintered material. The porous samples are filled with water and tested by using the pulse transmission method and immersion technique. The experimental data for wide frequency rangeę are processed derived by using of spectral analysis. The comparison of theoretical and experimental results shows good qualitative agreement between the predictions and experimental data.