Influence of Blood Rheology and Outflow Boundary Conditions in Numerical Simulations of Cerebral Aneurysms - Mathematical Methods and Models in Biomedicine - page 158

0 . 25 cm, the side-branch radius of 0 . 075 cm, and the aneurysm radius of 0 . 4cm.The

side-branch length is 1 . 2 cm. The idealized geometry volumetric mesh is composed

of approximately 0 . 5 M tetrahedral elements, with elements of size 0 . 02 cm.

5 Discussion

5.1 Idealized Geometry

Hemodynamics inside the idealized aneurysm was studied using the Newtonian and
Carreau fluid models, both in steady and unsteady inflow regimes, including and
excluding a side-branch within the aneurysm, and prescribing four different types
of outflow boundary conditions on the side-branch: traction-free (TF), no-slip (NS),
3D-1D coupling (1D), and 3D-0D coupling (0D). At the outflow section of the
main vessel a traction-free boundary condition was always prescribed.
The differences between the Newtonian and Carreau solutions, for both steady
and unsteady regimes, are depicted in Fig. 7 (velocity) and Fig. 8 (WSS). The
geometry considered for these results is the idealized with hole (clipped side-
branch), and the traction-free condition at this outflow boundary. The maximum

Fig. 7 Velocity magnitude (cm/s) for the clipped geometry with traction-free conditions at
the side-branch outflow, using the Newtonian ( top ) and the Carreau ( middle ) models, and its
differences ( bottom ), for the unsteady and steady solutions. The maximum difference is calculated
for the cross-section, using the maximum value for the percentage