Attenuation and group speed in water-saturated granular materials at MHz frequencies

作者：Hare Jenna; Hay Alex E^*

来源：Journal of the Acoustical Society of America, 2018, 143(5): 2744-2755.

DOI：10.1121/1.5033901

Attenuation and group speed measurements are reported for water-saturated granular materials (natural sand and glass beads) at frequencies of 1.0 to 1.8 MHz. Median grain diameters were 219 to 497 mu m, corresponding to kd greater than or similar to 1, i.e., the scattering regime. The measurements were made for different thicknesses of sediment resting on a reflective surface using a monostatic geometry. The attenuation estimates compare well with previously reported experimental results and to the predictions of multiple scattering theory, confirming in particular the tendency toward f(4) dependence for kd greater than or similar to 1. Group speed estimates exhibit the negative dispersion predicted by theory and are comparable in magnitude to previously reported measurements made using transmission geometries. It is found that the available data exhibit a O(10)% spread among the sound speed measurements at a given kd value, and that this spread is reduced to 2.2% when the data are scaled by a factor dependent on porosity and grain density, and that essentially all of the reduction can be attributed to differences in porosity.

• 出版日期2018-5