1. Introduction

The vibratory behavior of a structure is often modified if it is in the presence of a fluid: this is called vibro-acoustic coupling. Coupling cases are distinguished into two categories: either the fluid is infinite (this is the case of submerged structures), or the fluid is contained in a bounded medium (this is the case of reservoirs more or less filled with fluid).

The finite elements described here make it possible to solve coupling problems with a finite dimensional fluid.

General notes:

\(P\):	instantaneous total pressure at a point in the fluid,
\({p}_{0}\):	pressure at rest,
\(p\):	sound pressure,
\({\rho }_{t}\):	instantaneous total density at a point in the fluid,
\({\rho }_{0}\):	density of the fluid at rest,
\(\rho\):	acoustic density,
\({\rho }_{S}\):	density of the structure,
\({\mathrm{u}}_{f}\):	acoustic displacement,
\(u\):	moving the structure,
\(\varphi\), \(\mathrm{\Phi }\):	fluid displacement potential,
\(\psi\), \(\mathrm{\Psi }\):	fluid speed potential,
\(\omega\), \(f\):	pulsation, frequency,
\(c\):	speed of sound in the fluid,
\(\lambda\), \(k\):	wavelength, wave number,
\(\sigma\):	structure stress tensor,
\(\varepsilon\):	structural deformation tensor,
\(C\):	structural elasticity tensor,
\(T\):	fluid stress tensor.