This work investigates the complex flow dynamics in patient-specific compliant models of Abdominal Aortic Aneurysms (AAA) using time-resolved Particle Image Velocimetry (PIV). Scans of multiple planes were performed on three different models: a healthy aorta, a 4-cm saccular AAA, and a 7-cm fusiform AAA. We discuss the differences in flow patterns in patient-specific models compared to idealized models from previous work. We note that the curvature of the aorta upstream from the aneurysm, specific placement of the iliac arteries, and the overall symmetry of the aneurysm have important effects on flow structures, such as increasing transient effects, vortex formation, and wall impingement. Viscous energy dissipation rate (VEDr) was also evaluated as it has been previously identified as a potentially good metric to assess the severity of some vascular diseases.
Finally, a modal analysis was performed on the velocity fields using Proper Orthogonal Decomposition (POD). The main modes obtained were inspected to identify the dominant structures, and the distribution of energy between the modes (Shannon entropy), and to create a reduced-order model of the flow. The results show that Shannon entropy was significantly different between the three models, suggesting that it can be a promising clinical parameter to evaluate the severity of AAAs
