# FSI Fluid-structure interaction and vibroacoustics

Fluid-structure interaction problems can be stronly non-linear and thus difficult to model specially when thin flexible structures are immersed in a fluid flow as for instance for an artificial cardiac valve. The classical ALE (Arbitrary Lagrangian Eulerian) approach is largely use to treat these problems. However, it has the disadvantage of needed a conforming mesh on the fluid-structure interface: the fluid mesh needs to be updated during the time integration process.

Noise reduction for passengers comfort in transport industry is now an important constraint to be taken into account during the design process. This process involves to study several configurations of the structures inside a given acoustic cavity in the context of an optimization, uncertainty or reliability study for instance. The finite element method can be used to model this coupled fluid-structure problem but needs an interface conforming mesh for each studied configuration which may become time comsuming.

In the context of interior noise reduction for the transport industry, porous materials have been used extensively as passive noise control solutions. The need for optimum price-performance ratio implies optimization in the design process, during which several simulations have to be run. However, numerically expensive modelling of porous material combined with the need for refined structural-acoustic finite element (FE) models can lead to prohibitive size of problems to solve.

Ces recherches sont effectuées en collaboration avec le département aéroélasticité et dynamique des structures DADS de l’ONERA (J.S. Schotté, G. Morchelewicz).