Three-field partitioned analysis of fluid–structure interaction problems with a consistent interface model

Abstract

This paper proposes a new Fluid–Structure Interaction computational framework. The coupling between the solid and an incompressible fluid is formulated by means of the method of localized Lagrange multipliers (LLM). Instead of applying a direct coupling between the fluid and the structure, which is the traditional approach, LLM introduces an intermediate surface with its own degrees of freedom that is connected to the fluid and structure sides using independent fields of localized Lagrange multipliers. This approach allows the connection of non-matching meshes with mortar or classical localized methods and provides consistent dynamic equations of motion for the interface that can be integrated in parallel. Interface multipliers are later eliminated and the interface motion is used to update the fluid and structure states. This way, dedicated stand-alone software modules for the fluid and the structure are connected to a third interface system treating their interaction, thus preserving the modularity of the single-discipline software modules. Different numerical examples are solved with the proposed methodology to prove its efficiency and accuracy by running a series of classical dynamic FSI benchmark problems.