Guided wave modes in porous cylinders: experimental results

In this paper guided wave modes in porous media are investigated. A water-saturated porous cylinder is mounted in the test section of a shock tube. Between the porous sample and the wall of the shock tube a water-filled annulus exists. For very small annulus width, bulk waves are generated and one-dimensional modeling is sufficient. Otherwise two-dimensional effects become important and multiple guided wave modes occur. Using a newly developed traversable positioning system in the shock tube, the frequency-dependent phase velocities and damping coefficients in the 1-120 kHz frequency range were measured. Prony's method was used for data processing. Agreement was found between the experimental data and the two-dimensional modeling of the shock tube which was based on Biot's theory.