An accelerated, fully-coupled, parallel 3D hybrid finite-volume fluid–structure interaction scheme

In this paper we propose a fast, parallel 3D, fully-coupled partitioned hybrid-unstructured finite volume fluid–structure-interaction (FSI) scheme. Spatial discretisation is effected via a vertex-centred finite volume method, where a hybrid nodal-elemental strain procedure is employed for the solid in the interest of accuracy. For the incompressible fluid, a split-step algorithm is presented which allows the entire fluid–solid system to be solved in a fully-implicit yet matrix-free manner. The algorithm combines a preconditioned GMRES solver for implicit integration of pressures with dual-timestepping on the momentum equations, thereby allowing strong coupling of the system to occur through the inner solver iterations. Further acceleration is provided at little additional cost by applying LU-SGS relaxation to the viscous and advective terms. The solver is parallelised for distributed-memory systems using MPI and its scaling efficiency evaluated. The developed modelling technology is evaluated by application to two 3D FSI problems. The advanced matrix-free solvers achieve reductions in overall CPU time of up to 50 times, while preserving close to linear parallel computing scaling using up to 128 CPUs for the problems considered.