Wave propagation in a stratified fluid / porous medium is studied here using
analytical and numerical methods. The semi-analytical method is based on an
exact stiffness matrix method coupled with a matrix conditioning procedure,
preventing the occurrence of poorly conditioned numerical systems. Special
attention is paid to calculating the Fourier integrals. The numerical method is
based on a high order finite-difference time-domain scheme. Mesh refinement is
applied near the interfaces to discretize the slow compressional diffusive wave
predicted by Biot's theory. Lastly, an immersed interface method is used to
discretize the boundary conditions. The numerical benchmarks are based on
realistic soil parameters and on various degrees of hydraulic contact at the
fluid / porous boundary. The time evolution of the acoustic pressure and the
porous velocity is plotted in the case of one and four interfaces. The
excellent level of agreement found to exist between the two approaches confirms
the validity of both methods, which cross-checks them and provides useful tools
for future researches.Comment: Wave Motion (2012) XX