Numerical Study on Thoracic Aortic Aneurysms: The Aneurysm Aggravation Effects on the Secondary Flow Motion

Abstract

It is well know  that there is a strong correlation between artery wall diseases and the flow structure disturbance. Aneurysms are enlargements situated at different but specifics parts of the vascular system; it is a silent diseas that evolves in time. The thoracic aortic aneurysms  (T. A. A) remains relatively unstudied and therefore the present study aimis is to clarify the effects of the  (T . A. A) evolution and the geometrical variations on both hydrodynamic instabilities inside the aortic bulge especially the vortex ring phenomenon and the secondary motion (Dean and lyne vortices) downsream the aneurysms.  Two different cases of asymmetric enlargements in the ascending part of the aortic are studied for both newtonien and the shear-thinning model to mimic the blood rheology inside the aneurysms bulge in order to investigate both parameters impact on the vortex ring behavior. Results schowed that the blood rheoligy effects the propagation velocity while the aneurysms size influences the vortex ring rupture,  the motion of the ring interaction with an inclined wall phenomenon. Results also showed that vortex ring disturbs the boundary layer and therefore the secondary motion in the rest of the aorta.