<html> <head> <TITLE>Abstract 97</TITLE> </head> <BODY BACKGROUND="backgcitblue.gif"> <BODY> <h3><I>Finol, E.A., Keyhani, K., and Amon, C.H., </I><B>"The Effect of Asymmetry in Abdominal Aortic Aneurysms under Physiologically Realistic Pulsatile Flow Conditions", <em>ASME Journal of Biomechanical Engineering</em>, Vol. 125, pp. 207-217, 2003.</B></h3> <IMG SRC="rain_line.gif" width="700" height="4"><P> <B>ABSTRACT</B><P> In the abdominal segment of the human aorta under a patient s average resting conditions, pulsatile blood flow exhibits complex laminar patterns with secondary flows induced by adjacent branches and irregular vessel geometries. The flow dynamics becomes more complex when there is a pathological condition that causes changes in the normal structural composition of the vessel wall, for example, in the presence of an aneurysm. This work examines the hemodynamics of pulsatile blood flow in hypothetical three-dimensional models of individual Abdominal Aortic Aneurysms (AAAs). Numerical predictions of blood flow patterns and hemodynamic stresses in AAAs are performed in single-aneurysm, asymmetric, rigid wall models using the finite element method. We characterize pulsatile flow dynamics in AAAs for average resting conditions by means of identifying regions of disturbed flow and quantifying the disturbance by evaluating flow-induced stresses at the aneurysm wall, specifically wall pressure and wall shear stress. Physiologically realistic abdominal aortic blood flow is simulated under pulsatile conditions for the range of time-average Reynolds numbers 50 d" Re<sub>m</sub> d" 300, corresponding to a range of peak Reynolds numbers 262.5 d" Re<sub>peak</sub> d" 1575. The vortex dynamics induced by pulsatile flow in AAAs is depicted by a sequence of four different flow phases in one period of the cardiac pulse. At peak flow, the highest wall shear stress and wall pressure levels are obtained at the distal end of the aneurysm. Peak wall shear stress and peak wall pressure are evaluated as a function of (i) the time-average Reynolds number and (ii) the asymmetry parameter ². <P> </BODY></html>