Hemodynamic characterization of abdominal aortic fusiform aneurysm: insights from computational fluid dynamics simulations

This numerical study consists of two different phases. In phase I, the blood flow is numerically simulated in a pipe with a diameter of 3.5 mm and a length of 61.6 mm with a vascular dilation (d/D) range from 1 to 2.6 (0–160%) where d is the dilation diameter and D is the straight cylindrical vessel diameter. In phase II, the simulations are performed on two models built based on the computed tomography angiography of the actual case of a patient-specific abdominal aorta fusiform aneurysm and a healthy case of the abdominal aorta. This numerical study aims to investigate the blood flow behavior and wall shear stress distribution in vascular dilations, focusing specifically on abdominal aortic aneurysm cases. Computational fluid dynamics simulations are performed on benchmark geometries and two computed tomography angiography-based models of abdominal aortic, one from a 54-year-old woman with abdominal aortic aneurysm and another from a healthy 43-year-old woman. The simulations utilize Ansys Fluent package software with boundary conditions obtained from patient data via ultrasonography. The results reveal distinct flow regimes in vascular dilations, including stable flow, critical flow, transient flow, and stable flow with recirculation. In abdominal aortic aneurysm cases, reduced blood velocity and complex flow patterns with recirculation zones are observed within the aneurysm zone. Wall shear stress distribution varies throughout the cardiac cycle, with higher values during systole and at bifurcations, highlighting the importance of fluid-wall interactions.