We compare the relative performance of
monolithic and segregated (partitioned) solvers for large-displacement
fluid-structure interaction (FSI) problems within the framework of
oomph-lib, the object-oriented multi-physics
finite-element
library,
available as open-source software at
http://www.oomph-lib.org.
Monolithic solvers are widely acknowledged to be more robust than
their segregated counterparts, but are believed to be too expensive
for use in large-scale problems. We demonstrate that monolithic
solvers are competitive even for problems in which the fluid-solid
coupling is weak and, hence, the segregated solvers converge
within a moderate number of iterations. The efficient monolithic
solution of large-scale FSI problems requires
the development of preconditioners for the iterative
solution of the linear systems that arise during the solution of the
monolithically-coupled fluid and solid equations by Newton's method.
We demonstrate that recent improvements to oomph-lib's FSI
preconditioner result in mesh-independent convergence rates
under uniform and non-uniform (adaptive) mesh refinement, and
explore its performance in a number of two- and three-dimensional
test problems involving the interaction of finite-Reynolds-number
flows with shell and beam structures, as well as finite-thickness solids.