ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

clarify the factors that cause aneurysms to expand and rupture. In this research, we
examined the effect to aneurysm after treatment for MAA using CFD analysis.
3. METHODS
3.1 Construction modeled shape
To clarify the effect of post treatment for MAA, three models were constructed as
shown in Figure 1. Figure 1(a) shows the model of the aorta with AAA and TAA before
treatment, Figure 1(b) shows the model of the aorta after the treatment of AAA, and
Figure 1(c) shows the model of the aorta after the treatment of TAA. In this paper, we
called these models as Figure 1(a): multiple, 1(b): upstream, and 1(c): downstream. The
radius of the arch was set to 0.03 [m] (6) . The diameter of the aorta set to 0.025 [m] (6) .
The diameter of aneurysm set to 0.05 [m] because surgery is performed when the
diameter of aneurysm becomes two times bigger than the diameter of the aorta. The
models were constructed using GAMBIT 2.4.6 and were analyzed using OpenFOAM.
Fig.1 Three models: multiple aneurysm (left), upstream aneurysm (middle), and
downstream aneurysm (right)
3.2 Calculation and Boundary Conditions
The blood flow was simplified as isothermal, incompressible, and Newtonian flow with
density of 1050 [kg/m 3 ] and a viscosity of 0.0035 [Pa·s].
As for boundary conditions, many studies about AAs use time dependent inlet velocity
(6) (7) . Figure 2 shows a time dependent inlet uniform velocity profile that indicates the
peak systolic conditions of the cardiac cycle.
In the case of this research, we used CFD analysis to compare pressure and WSS at
aneurysms before and after treatment. To examine results using same condition in three
models, the pressure difference is fixed to pressure difference of healthy aorta model as
shown in Figure 3 (left). To obtain the pressure difference between inlet and outlet
position, the inlet boundary condition is set to inlet velocity profile as shown in Figure 2,
and the outlet boundary condition is set to zero uniform pressure. Using CFD analysis,
we computed pressure difference between inlet and outlet of healthy aorta. This
obtained pressure difference was used as boundary condition for three models as shown
in Figure 3(right).