  Computational fluid dynamics (CFD) in combination with patient-specific
medical images has been used to correlate flow phenotypes with disease
initiation, progression and outcome, in search of a prospective clinical tool.
A large number of CFD software packages are available, but are typically based
on rigid domains and low-order finite volume methods, and are often implemented
in massive low-level C++ libraries. Furthermore, only a handful of solvers have
been appropriately verified and validated for their intended use. Our goal was
to develop, verify and validate an open-source CFD solver for moving domains,
with applications to cardiovascular flows. The solver is an extension of the
CFD solver Oasis, which is based on the finite element method and implemented
using the FEniCS open source framework. The new solver, named OasisMove,
extends Oasis by expressing the Navier-Stokes equations in the arbitrary
Lagrangian-Eulerian formulation, which is suitable for handling moving domains.
For code verification we used the method of manufactured solutions for a moving
2D vortex problem, and for validation we compared our results against existing
high-resolution simulations and laboratory experiments for two moving domain
problems of varying complexity. Verification results showed that the $L_2$
error followed the theoretical convergence rates. The temporal accuracy was
second-order, while the spatial accuracy was second- and third-order using
P1/P1 and P2/P1 finite elements, respectively. Validation results showed good
agreement with existing benchmark results, by reproducing lift and drag
coefficients with less than 1% error, and demonstrating the solver's ability to
capture vortex patterns in transitional and turbulent-like flow regimes. In
conclusion, we have shown that OasisMove is an open-source, accurate and
reliable solver for cardiovascular flows in moving domains.
