2023 Volume 37 Issue 1 Pages 21-34
There still remains uncertainty about the result of hemodynamic analysis of the intracranial aneurysm by computational fluid dynamics (CFD) because a variety of computational conditions are used by different analysts. In particular, the impact of the outflow boundary condition imposed at the outlets has not been fully elucidated, although it is considered to play an important role in determining the hemodynamic state in a bifurcation aneurysm. The purpose of this study is to discuss quantitative influences of different outflow boundary conditions on computed wall shear stress (WSS) in the aneurysm in terms of rupture risk assessment. Using three patient-specific models of aneurysms, the authors conducted hemodynamic analysis and compared the maximum, minimum and mean WSSs evaluated with seven outflow boundary conditions: the zero-pressure condition, five power laws with different exponents and Windkessel model. In one of the three models, even a slight difference in the power-law exponent caused a significant difference larger than 0.2 Pa in the minimum WSS, which could lead to misjudgement in rupture risk assessment. No particular outflow condition proved superior to the others. However, it was suggested that the Windkessel could perform better if the patient-specific information about the distal flow resistance were available.
