Parallel partitioned coupling analysis system for large-scale incompressible viscous fluid-structure interaction problems

Fluid-structure interaction (FSI) affects the dynamic characteristics and behaviors of the fluid and structure, and being able to understand and solve FSI problems is very important in engineering, science, medicine, and everyday life. Generally, FSI problems are simulated by either monolithic or partitioned methods. There are still many challenges in the development of better numerical methods for FSI problems in terms of accuracy, problem scale, stability, robustness, and efficiency. We have focused on partitioned methods because they allow the use of existing flow and structural analysis solvers without elaborate modification. This paper describes the development of a parallel partitioned coupling analysis system for large-scale FSI problems. In this study, we employed the existing flow and structural analysis solvers FrontFlow/blue (FFB) and ADVENTURE_Solid, respectively, both of which are general-purpose codes used to solve large-scale analysis models ranging from millions to billions of degrees of freedom (DOFs). In addition, we developed a parallel coupling tool called ADVENTURE_Coupler to efficiently handle the exchange of interface variables in various parallel computing environments. To achieve the robust and fast convergence of the fixed-point iteration, we employed Broyden's method, which is a quasi-Newton method, to update the interface variables. We verified the accuracy and fundamental performance of the developed FSI analysis system by using it to solve a FSI benchmark problem: the vortex-induced oscillation of a flexible plate in the wake of a square column. The results agreed quantitatively well with other researchers' results. Finally, we successfully applied the system to the analysis of the three-dimensional flapping motion of an elastic rectangular plate, with the objective of furthering the research and development of micro air vehicles (MAVs) with flapping wings.