A Fully Stabilized Combined Field Formulation for Coupled Fluid-Structure Interactions

We present a fully coupled three dimensional formulation based on arbitrary Lagrangian-Eulerian (ALE) approach with exact interface tracking for nonlinear fluid-structure interactions. This formulation is second order accurate in time and stable for very low mass ratios of O(10). The proposed formulation is an extension of the combined field with explicit interface (CFEI) presented in [1, 2] for two-dimensional framework. The CFEI is a monolithic nonlinear coupled fluid-structure formulation with explicit/implicit time integration. In the CFEI formulation the fluid-structure interface is explicitly determined at the start of each time step. This enables decoupling of ALE mesh from the remaining variables (structural velocity, fluid velocity and pressure) and consequently requires an explicit treatment of convective velocity. Hence, the CFEI formulation needs to solve the system of linear equations only once per time step. Additionally, the combined field formulation [2] absorbs the traction and velocity continuity equations into its weak form resulting in lesser number of linear equations per time step.