Fluid–Structure Interaction Model for Assessing Aneurysm Initiation at the Circle of Willis

Abstract

Hemodynamics associated with the arteries of the circle of Willis (CoW) is analyzed to identify possible cerebral aneurysm initiation locations using computational methods. A numerical fluid–structure interaction model is developed using an idealized geometry with the linear elastic, isotropic arterial wall. Blood flow is assumed to be laminar, incompressible, and modeled using Navier–Stokes equations, non-Newtonian viscosity, and sinusoidal boundary conditions. Available analytical and experimental results are used for the validation of the model. The highest wall shear stress (WSS) and von Mises stress (VMS) are identified for understanding the most vulnerable sites. The WSS distribution in the entire CoW region shows that ACoA junction has the highest value and risk of aneurysm initiation. The flow patterns created due to the geometrical features of the CoW seem to be the significant factor in the distribution of WSS. It is noticed that a decrease in wall elasticity will reduce the magnitude of WSS, both the temporal and spatial averaged value. The wall weakening effects are more pronounced for the posterior communicating artery. The wall weakening creates changes in core velocity and WSS. Changes in Von Mises stress are also noticed due to wall weakening effects. Highly localized VMS is noticed at ACoA and could possess a higher risk for aneurysm initiation and rupture. Despite the simplifications involved in developing the fluid–structure interaction model, this work demonstrates the critical locations at the CoW region regarding aneurysm initiation.