1. Introduction

Simulating the aeroelastic behaviour of realistic configurations such as airplane wing assemblies or turbomachinery components is now within the capabilities of computer power and numerical methods. However, the process can become an extremely long and costly enterprise, especially when precise methods are demanded. Often it is sufficient to use frequency domain techniques based on linearised equations and a linear relationship between the aerodynamic loads and the structural deformation. These methods fail when non-linear effects are important such as vibrating shocks as in transonic regimes or non linearities in the structure properties, then time domain methods are necessary. The fluid and the structural equations can be solved separately or together, in each case the reaction of the fluid from the deforming structure and vice versa takes place at the interface between the two. For example, an aeroelastic fluid-structure interaction computation requires that the airloads induced by the flow on the solid are translated via a boundary condition as the external forces for the structural mechanics calculation, which in turns leads to a deformation of the structure which needs to be accounted for in the fluid dynamics simulation. In general, the geometrical representation and the numerical techniques used in the fluid and structural mechanics computations are not the same; as a result the coupling of these two simulation methods requires algorithms that maintain energy transfer...