Bandgap calculations of two-dimensional solid-fluid phononic crystals with the boundary element method

► A boundary element method (BEM) for solid-fluid phononic crystals is developed. ► The solid-fluid interface conditions can be considered. ► The transverse wave mode in the solid has great effect on the band structures. ► The localization mode of the fluid scatterer disappears with its density increasing. ► BEM is efficient for the fluid-solid systems with non-circular scatterers.