A matrix-free, implicit, incompressible fractional-step algorithm for fluid–structure interaction applications

In this paper we detail a fast, fully-coupled, partitioned fluid–structure interaction (FSI) scheme. For the incompressible fluid, new fractional-step algorithms are proposed which make possible the fully implicit, but matrix-free, parallel solution of the entire coupled fluid–solid system. These algorithms include artificial compressibility pressure-poisson solution in conjunction with upwind velocity stabilisation, as well as simplified pressure stabilisation for improved computational efficiency. A dual-timestepping approach is proposed where a Jacobi method is employed for the momentum equations while the pressures are concurrently solved via a matrix-free preconditioned GMRES methodology. This enables efficient sub-iteration level coupling between the fluid and solid domains. Parallelisation is effected for distributed-memory systems. The accuracy and efficiency of the developed technology is evaluated by application to benchmark problems from the literature. The new schemes are shown to be efficient and robust, with the developed preconditioned GMRES solver furnishing speed-ups ranging between 50 and 80.