In this paper, the interior elastoacoustic problem in a 3D domain is solved
. Displacement variables are used for both the fluid and the solid. To avoi
d the typical spurious modes of this formulation, a non-standard discretiza
tion is used, consisting of classical linear tetrahedral finite element for
the solid and Raviart-Thomas elements of lowest order for the fluid. A new
unknown is introduced on the interface between solid and fluid to impose t
he transmission conditions. (C) 1999 Academic Press.