Interface treatment in computational fluid-structure interaction

Computational approaches for the simulation of fluid-structure interaction (FSI) problems have received much attention in recent years and their importance is still continuously growing. The main reason for this is that FSI problems are of great relevance in all fields of engineering (civil, mechanical, aerospace, bio, etc.) as well as in the applied sciences. In order to develop robust, reliable and efficient methods a number of challenges have to be met. This contribution focuses on the important question of how to treat the interface between solid and fluid. The topic is addressed by reviewing our novel, recently proposed method for dealing with nonmatching grids in the context of moving grid FSI schemes. In contrast to available approaches in the literature, the proposed formulation is based on a mortar method with so-called dual Lagrange multipliers and handles the additional complexity of coupling non-matching interface meshes at negligible computational cost. Owing to its generality, the resulting FSI framework does not introduce any restriction on the particular choice of finite element formulations neither for fluid, ALE nor structure. It allows for the application of state-of-the-art iterative solution methods to the resulting system matrices in a straightforward manner and shows an excellent performance within monolithic FSI coupling algorithms.