Analysis of porous plate/water layered structures by means of the transition terms method

Abstract

This paper is devoted to the study of water-saturated porous plate/water layered structures by means of the transition terms defined from the reflection and transmission coefficients. Transition terms are obtained from the eigenvalues of the scattering matrix of the water-immersed structure and exhibit the symmetric or antisymmetric resonances of the structures. The N porous plates associated in our structures obey Biot's theory. The reflection and transmission coefficients of a unique water-saturated plate being calculated, an induction on N process allows to find the reflection and transmission coefficients of a given N plate/water-layer structure. The plates used in the experiments at normal incidence are 5mm thick. The reflection and transmission coefficients of sets of 1, 2, 3, and 4 water immersed plates, separated from each other by a 1cm water gap, are measured. There are good agreements between the calculated and experimental transition terms. Which obey the Breit-Wigner resonant form which characteristics can be obtained.