Numerical simulation of blood hammer phenomenon in the posterior cerebral artery incorporating visco-hyperelastic wall and complex fluid–structure interaction

This study numerically investigates the blood hammer phenomenon in an occluded posterior cerebral artery, accounting for fluid–structure interaction between the arterial wall and the blood. The non-Newtonian characteristics of blood—such as shear-thinning and viscoelasticity—are modeled using suitable constitutive equations, while rigid, hyperelastic, or visco-hyperelastic models represent the arterial wall. To examine the impact of different wall rheological models, blood dynamics are primarily described using the five-mode Phan–Thien–Tanner (PTT) viscoelastic model, which captures the complex interaction between blood flow and the arterial wall. For the visco-hyperelastic wall case, alternative constitutive equations for blood are also employed to explore model sensitivity. Key hemodynamic parameters—including velocity profiles, tensile stress distributions, pressure wave histories, and wall shear stresses—are compared across the various combinations of blood and wall models. Results show that when the arterial wall is modeled as visco-hyperelastic, the pressure wave period shortens, and both pressure and wall shear stress histories exhibit the best attenuation. Velocity and tensile stress distributions are also strongly dependent on the wall's rheological properties. When blood is modeled with viscoelastic constitutive equations, attenuation of pressure waves and wall shear stress is weaker compared with viscoplastic or purely shear-thinning models. Under fluid–structure interaction conditions, the maximum wall shear stress predicted by the FENE-P model is reduced by 100%, 43.26%, and 8% relative to the Carreau, Casson, and PTT models, respectively. Hemolysis analysis indicates that red blood cell damage is highest at the arterial midpoint along the wall, rather than at the occlusion site. This effect is most pronounced during the first period of the process, with a peak hemolysis value of 0.954%, indicating a potential health risk.