Sttented Aneurysm Model

Fig. 4 shows the flow volume rate for the inlet and outlet in the stented aneurysm model. It is expressed by: (4) where V is the flow velocity and A is the cross-sectional area of the aorta. During one cycle, the flow volume passing through the outlet is the same as the flow volume passing through the inlet. This indicates that conservation of mass in the fluid flow is satisfied. The contours of pressure change in fluid domain for six different values of intraluminal thrombus elasticity modulus in case of filled cavity at the time of peak pressure have been depicted in Fig. 5. Modulus of elasticity of thrombus

8 shows velocity contours for stented aneurysm model with different thrombus depth that varies from 10% to 100% at the time of peak flow when Eth= 0.2MPa. At the entrance of the aneurysm, the blood flow velocity is much higher than that of downstream. It can be seen that the velocity increases by the growth of thrombus depth and this may be due to reduction in cross-sectional area at the distal neck. Figs. 9 and 10 present the von Mises stress distribution along the wall thickness at the inflection points when entire cavity of aneurysm is filled with thrombus at the time peak flow and peak pressure, respectively. It can be seen that the media layer has the highest stress among three layers. Furthermore, the wall stress decreases by the value of 46% at the time of peak flow and 38% at the time of peak pressure as the elastic modulus of thrombus increases from 0.1 MPa to 2 MPa. Figs.11 and 12 show von Mises stress distribution along the wall thickness as the thrombus depth with the elastic modulus of 0.2 MPa fills 10% to 100% of the entire cavity at the time of peak flow and peak pressure, respectively. By increasing thrombus depth the wall stress is reduced. This reduction is considerable when the thrombus depth is higher than 60%. moreover, the wall stress decreases by the value of 27% at the time of peak flow and 22% at the time of peak pressure as thrombus depth grows from 10% to 100%.

4.

A two-dimensional axisymmetric model of aortic aneurysm with various both depth and elastic modulus of thrombus in the presence of pulsatile flow with considering fluid-solid interaction was simulated. The results revealed that the wall stress decreases by the growth of thrombus elastic modulus for both times of peak flow and peak pressure and the difference between pressure values of the inlet and outlet at the time of peak pressure decreases in the case of reduction in difference between elastic modulus of intima and thrombus. Furthermore, at the time of peak flow as the thrombus elastic modulus closes to that of intima, the blood flow velocity increases. The amount of thrombus depth has significant effect on wall stress at both times of peak flow and peak pressure in such a way by increase in thrombus depth, the wall stress can be decreased and when thrombus depth is approximately higher than 50% of entire cavity, the pressure and velocity increases at the peak pressure and velocity times, respectively. Our results also show that the media layer is subjected to higher loads than other layers and that the stresses are much higher in the media layer in all cases. The achievements of this study can help the researchers by providing more detailed information about aortic aneurysm