Theoretical and experimental studies of surface waves on solid–fluid interfaces when the value of the fluid sound velocity is located between the shear and the longitudinal ones in the solid

The existence of two surface waves propagating on a plane solid–fluid interface is demonstrated when the value of the fluid sound velocity is located between the shear and the longitudinal ones in the solid. First, the Scholte–Stoneley dispersion equation is studied analytically and numerically to find the roots corresponding to the Stoneley and the Rayleigh waves. The anatomy of each one is then described with the formalism of the evanescent plane waves: both waves are unleaky. Finally, the results are confirmed experimentally by measuring the times of flight on a Plexiglas–water interface and on a PVC–water interface.