Guided wave propagation along the surface of a one-dimensional solid-fluid phononic crystal

We consider an arbitrary periodic corrugated surface of a semi-infinite elastic solid that is immersed in a fluid, forming a one-dimensional phononic crystal. We study the existence and the polarization of guided waves that propagate along the interface. A coupled elastic-acoustic variational model is devised to obtain the dispersion of guided waves, which is implemented with a finite element method. It is found that the deeply corrugated interface supports a family of interface waves whose phase velocity decreases as the corrugation depth increases. Among these interface waves, some display an evanescent decay in the fluid that is reminiscent of the Scholte-Stoneley wave, while others propagate in the solid without causing significant pressure variation in the fluid, or cause localized pressure variations only inside the corrugation openings. The obtained results open the way for the study of conversions between bulk and surface waves in solid-fluid phononic crystals, and their use for wave confinement at the surface.