Arterial circulation   Out of the heart, blood is conducted towards the vital organs through the aorta (diameter of 28mm at its root) which ramifies as it goes farther from the heart. The arterial tree features numerous native singularities: - curves (aortic arch) - bifurcations(carotidian, aorto-iliac, or kidney bifurcations, Willis polygon) - swelling (carotidian bifurcation) Some diseases of the vascular system modify the geometry and the structure of the original vascular network. It is for instance the case of atherosclerosis. The atheromateous lesions may partially or totally block the ducts. Such stenoses hence lead to a decrease of the arterial diameter.     Formation of a stenosis by development of an atheromateous lesion   The cardio-vascular affections may also show up by the development of an anevrism, in particular inbound the abdominal aorta. Finally, regular surgery acts to restore a satisfying flow such as grafts or bridgings may also modify the native spatial configuration and hemodynamics. In any case, peculiar fluid phenomena are induced by these changes in configuration. Still, it has been clearly prooved that local hemodynamics was one of the parameter accounting for the initiating and the development of some pathologic processes. Biomechanics researchers have actually manage to establish correlations between the most common sites of development of athrosclerosis, and the lining shear: sites of weak/oscillating friction are convenient to the progression of the arterial disease. Seeting up models of these flows therefore allows to designate more accurately the potentially dangerous areas of the arterial tree.     Sane abdominal artery Anevrism