The Role of Wall Mechanics in the Hemodynamics of a Realistic Abdominal Aortic Aneurysm: A Fluid-Structure Interaction Study

Abdominal aortic aneurysm (AAA) can lead to high mortality rates and further complications such as stroke or heart attack due to the risk of rupture and thrombosis. Wall mechanics play a crucial role in the development and progression of aneurysms. This study investigated the effects of wall mechanics on hemodynamic parameters in AAA to understand the risk of rupture and thrombosis. The impact of three aortic wall models (rigid, linear elastic, and hyperelastic) on structural and hemodynamic parameters was examined using CFD and FSI techniques. The blood was modeled using the Carreau non-Newtonian model, and the flow was simulated using the k-ω model. Physiological pulses were used for the velocity at the inlet and the pressure at the outlet. The results demonstrated close similarity between the predictions of the linear elastic and hyperelastic models, in contrast to the somewhat different results of the rigid model. The hyperelastic model predicted higher deformation and von Mises stress levels than the elastic model, although the difference in stress predictions was smaller than the difference in deformation predictions. The rigid model evaluated the time-averaged wall shear stress and oscillatory shear index higher than the other two models in the aneurysmal area but with a lower relative residence time. In general, the hyperelastic model predicted a higher risk of rupture than linear elastic models and a higher risk of thrombus formation than the other two models. The rigid model had the most optimistic prediction.