Fluid-structure interaction problem of a deformable lamina solved with an original OpenFOAM code

Abstract Fluid-structure interaction (FSI) problems regard multiphysics systems where structures interact with fluid flows. The structure is subjected to flow-related loads; as a consequence, structural displacements and oscillations influence the fluid motion field. Many engineering fields require the resolution of FSI problems, yet a comprehensive study of such problems remains a challenge due to their strong non-linearity and multidisciplinary nature. In order to investigate the physics involved in this complex interaction, numerical simulations may be employed. The partitioned approach is the numerical procedure used to build the here-described FSI solver, modsFsiFoam (MODalSuperpositionFsiFoam), in OpenFOAM, an opensource software developed for Linux distributions and released under a GPL license with the C++ source code. It has enabled to treat the fluid and the structure as two computational fields, which have been solved separately with their respective mesh discretization. In particular, it has allowed the application of two different methods for fluid and solid solutions. It has to be considered that in OpenFOAM environment several FSI solvers, based on the Finite Volume Method (FVM) for both fluid and structural solutions, can be found. Since satisfactory results have not been obtained, for the here-described solver it has been chosen, in relation to the structural solution, to replace the FVM, with a theoretical approach based on modal superposition. The FVM has been used instead to solve the Navier-Stokes equations for an incompressible laminar flow of Newtonian fluid. The interfacial conditions have been used to pass information between the domains through a coupling algorithm. In this paper, a specific 2D application of this solver on a simple system, made of a deformable lamina interacting with an air flow, is shown.