Fluid-structure interaction analysis using a 3D general frame element with positional formulation

Abstract

This project proposes to investigate the simulation of fluid-structure interaction problems employing a 3D general frame finite element. To this purpose, computational codes already developed by the research group where the project is inserted shall be used as a basis. This project seeks simulating such 3D problems in a realistic way. For simplicity, we deal with compressible inviscid flows in order to avoid turbulence problems and latter it should be extended to incompressible viscous flows. The problems to be studied involve mainly 3 different subjects: The computational fluid dynamics (CFD), the computational structural dynamics (CSD) and the coupling problem (CP). Many structures, like airplane wings and bridges, present one dimension much larger than the others, and so, may be represented by 3D general frame elements, needing less degrees of freedom to represent the structural kinematics, minimizing computational costs. The adopted frame element takes into account flexure, torsion and axial forces effects, including warping effect for any cross section. Once such element consists of one single line plus cross section discretization, a boundary mesh will be generated and coupled to the frame element, so that coupling is possible. Over this mesh, the surface forces taken from the flow pressure and shearing stresses are also multiplied by the frame element shape functions and integrated in order to generate nodal equivalent forces to the frame element. The position based formulation performs large displacements simulations avoiding the need for dealing with finite rotation approximations, sowing to be very robust. Regarding fluid dynamics, we use a finite element formulation, explicit for compressible and implicit for incompressible flow, which takes in account the structural movement by using the Arbitrary Lagrangian-Eulerian (ALE) description with a mesh adaptation algorithm. (AU)