  We present an operator-splitting scheme for fluid-structure interaction (FSI)
problems in hemodynamics, where the thickness of the structural wall is
comparable to the radius of the cylindrical fluid domain. The equations of
linear elasticity are used to model the structure, while the Navier-Stokes
equations for an incompressible viscous fluid are used to model the fluid. The
operator splitting scheme, based on Lie splitting, separates the elastodynamics
structure problem, from a fluid problem in which structure inertia is included
to achieve unconditional stability. We prove energy estimates associated with
unconditional stability of this modular scheme for the full nonlinear FSI
problem defined on a moving domain, without requiring any sub-iterations within
time steps. Two numerical examples are presented, showing excellent agreement
with the results of monolithic schemes. First-order convergence in time is
shown numerically. Modularity, unconditional stability without temporal
sub-iterations, and simple implementation are the features that make this
operator-splitting scheme particularly appealing for multi-physics problems
involving fluid-structure interaction.
