Study of non stationary mode flow of an abdominal aortic aneurysm.
BACKGROUND
Abdominal aortic aneurysm rupture is 95% lethal. Numerical simulation of Navier-Stokes equations allows seeing complex flow phenomenon in laminar state.


METHODS
In this study, we work on a model using the finite element method with an actual 3D geometry. This geometry is from a point cloud obtained by a tomodensitometry scan of a typical patient. We consider rigid wall, homogeneous and Newtonian fluid. We impose four pulsative waveforms as entrance condition: two rest waveforms, two exercise waveforms. The four aver-age Reynolds numbers are 353 and 363 for the rest waveforms and 1058 and 1388 for the exercise waveforms. For the systolic peaks, the Reynolds numbers are 1639 and 1917 for the rest waveforms and 2800 and 2497 for the exercise waveforms.


RESULTS
RESULTS show that during the systolic acceleration, vortices issued from the previous pulsation are pushed out and the flow reattached on the wall. During the systolic deceleration, a main vortex appears in the upper part of the aneurysm; it grows and moves to the center. During the diastole, the vortex sustains itself until the next pulsation for the exercise conditions. For the rest conditions, imposed oscillations during the diastole lead to secondary vortices. Pressure stays relatively constant in the aneurysm following the entrance conditions.


CONCLUSIONS
These results on the flow and pressure repartition agreed with those found in the literature (1-6) validating in a first time our model. The next step of the study is the wall shear stress data exploitation.
Geneves
C
C
Département de Génie Mécanique, Ecole Polytechnique de Montréal - Canada.
Wilquem
F
F
Treyve
F
F
Cloutier
G
G
Soulez
G
G
Saidane
K
K