Fluid Structure Interaction

The Problem

Fluid Structure Interaction (FSI) has received a growing focus of attention in both the fields of Computational Fluid Dynamics (CFD) and Finite Element (FE) analysis and examples are found in diverse fields. FSI requires a multi-physics approach, requiring multiple numerical models to be coupled together. Specifically, FSI is concerned with obtaining a numerical solution for the stresses and displacements of a structure, due to applied fluid and thermal loadings, and, determining how such displacements affect the fluid flow.

The Approach

The problem can be tackled by either a Monolithic approach that integrates the FSI as a single system and solves simultaneously for the fluid and the structure, or, a Coupled Field approach that couples separate structural and fluid solvers through various algorithms. This study focused on the theoretical and practical development of a novel Monolithic formulation that can be applied to the FSI problem. This required the development of appropriate boundary conditions for normal, shear and bending type problems as well as problems involving non-uniform torsion, in particular, warping of cross-sections and calculation of the Warping Function.

The Result

By expressing the Equations of Equilibrium in terms of displacements, both the fluid and the structure are able to be represented by a single general differential equation, this allows a single solution procedure to be enlisted for simultaneous FSI analysis. The formulation was tested successfully on numerous problems indicating its potential for use in this field.