Fluid-structure interaction of prismatic line-like structures, using LES and block-iterative coupling

The design of long-span bridges to resist wind loading often requires wind tunnel testing of sectional or full aeroelastic models. Recently, efforts have been made to realise a reliable computational alternative to these physical tests. In the current work, a novel computational scheme for fluid-structure interaction (FSI) is presented. Large eddy simulation (LES) for 3D viscous turbulent incompressible flow has been coupled to the response of prismatic line-like structures. LES is chosen because of the inherent unsteadiness in FSI problems and the capability of LES to maintain the turbulence structure in the flow, in contrast to the over-dissipativeness of the traditional Reynolds averaged Navier-Stokes equations (RANS)-based turbulence models. A Gauss-Seidel-type block-iterative algorithm is adopted to address both the field coupling and the non-linearity simultaneously. At global convergence, this gives solutions identical to those obtained using direct coupling, but with field modularity preserved, storage requirements well under control and computational effort significantly reduced. Numerical examples are presented for elastically supported rigid circular and rectangular cylinders (sectional model tests); the method is readily extendable to flexible structures (full aeroelastic models) via modal analysis.