Biomedical Engineering Reference
In-Depth Information
Fig. 4
3D models of an AAA. (
a
) Mechanical model and (
b
) fluidic model
fast and efficient manner, as in Fig.
4
. For an accurate representation, the model must
include the blood flow, the bifurcated stent-graft, the aorta wall motion (including
the aneurysm wall) and the stagnant blood inside the aneurysm sac (essential for the
pressure simulation inside the sac).
Due to the pulsatile nature of blood flow, transient simulations are often used to
model the blood flow. Aneurysms can have several geometries and sizes [
20
,
23
],
but AAAs present most commonly a fusiform geometry. The aorta radius ranges
from 2 to 2,5 cm and the wall thickness presents typical values around 2-2,5 mm
[
20
,
23
].
Figure
5
presents the main parameters of the 3D model implemented by the
authors to assess the pressure distribution inside the aneurysm sac. The ANSYS
multiple code coupling (MFX) with Fluid Solid Interface (FSI) coupling between
ANSYS and CFX was used to solve the model.
The blood flow is considered newtonian, laminar and incompressible; the density
is equal to 1.05 g/cm
3
and the viscosity is 0.0035 Pa.s.
The model uses an aorta radius and aorta wall thicknesses of 2.5 cm and 2.5 mm
respectively, and an aneurysm length of 10.5 cm and main radius of 6.7 cm.
