This paper describes a coupling scheme for fluid–structure interaction (FSI) applications extended to high-density fluids. The scheme is based on the classical iterative partitioned approach (one solver per physics), an approach easy to implement, but which traditionally has only been used in aeroelasticity applications. As fluid density increases convergence is no longer ensured, being clearly dependent on the ratio between the total fluid mass and the mass of the structure. An approach based on the estimation of the added mass matrix is here presented in detail, and validated using the classical 1D problem of a piston in a cylinder. Results are shown for a cylinder moving in a moderate fluid flow, and the case of an elastic membrane allows conclusions to be drawn regarding the applicability of this approach to general FSI cases.