Partitioned formulation of internal fluid–structure interaction problems by localized Lagrange multipliers Original Research Article

A partitioned formulation of compressible internal fluid–structure interaction problems is presented by employing a displacement model for both the fluid and structure. Partitioning is effected by a localized version of the method of Lagrange multipliers, which assigns two independent sets of Lagrange multipliers to the structural and fluid interfaces. Two major features of the present formulation include: an interface compliance normalization that helps capture the predominant physics of interaction phenomena when the interfaces are characterized by two radically different rigidities, and a novel transformation of the displacement model into a fluid-pressure model that is suitable for both transient and vibration analyses. The present formulation first solves for the interface Lagrange multipliers, which are subsequently used to solve for the structural displacements and the fluid displacement or pressure by employing two independent analysis modules.