Blood flow in abdominal aortic aneurysms: Pulsatile flow hemodynamics

Numerical predictions of blood flow patterns and hemodynamic stresses in Abdominal Aortic Aneurysms (AAAs) are performed in a two-aneurysm, axisymmetry, rigid wall model using the spectral element method. Physiologically realistic aortic bloodflow is simulated under pulsatile conditions for the range of time-averaged Reynolds numbers 50 less than or equal to Re(m)less than or equal to 300, corresponding to a range of peak Reynolds numbers 262.5 less than or equal to Re-peak less than or equal to 1575. The vortex dynamics induced by pulsatile flow in AAAs is characterized by a sequence of five different flow phases in one period of the flow, cycle. Hemodynamic disturbance is evaluated for a modified set of indicator functions, which include wall pressure (p(w)), wall shear stress (tau (w)), and Wall Shear Stress Gradient (WSSG). At peak flow, the highest shear stress and WSSG levels are obtained downstream of both aneurysms, in a pattern similar to that of stead), flow. Maximum values of wall shear stresses and wall shear stress gradients obtained tit peak flow tire evaluated as a function of the time-average Reynolds number resulting in a fourth order polynomial correlation. A comparison between predictions for steady anti pulsatile flow is presented, illustrating the importance of considering time-dependent flow for the evaluation of hemodynamic indicators.