Coupling of fluid structure interaction solver with a VOF method for multiphase structure interaction

In this work we propose a preliminary model to study the deformation of solid structures induced by the interaction with a two-phase flow. The study of Fluid Structure Interaction and multiphase problems is of great interest because of many potential applications ranging from the biomedical field to the pressure tank design. We use a monolithic approach for the FSI problem while a Volume Of Fluid method (VOF) is considered for the reconstruction and the advection of the multiphase interface. An unstructured, time dependent computational grid and a fine Cartesian mesh are used for the FSI and the VOF problem, respectively. The interaction between the two different grids is obtained by projecting the velocity and the displacement field into the Cartesian grid and the color function into the unstructured mesh. This projection is performed with the MEDmem libraries included in the Salome platform. Concerning the VOF method, for an accurate reconstruction of the interface a huge number of computational elements are required and a multilevel algorithm coupled to an efficient compression-expansion technique is developed to reduce computational costs and memory requirements. After the mathematical description of the problems we test the proposed algorithm with different cases where the solid domain undergoes to both small and large deformation.