FLUID-STRUCTURE INTERACTION ANALYSIS OF WALL STRESS AND FLOW PATTERNS IN A THORACIC AORTIC ANEURYSM

In this study, fluid-structure interaction (FSI) simulation was carried out to predict wall shear stress (WSS) and blood flow patterns in a thoracic aortic aneurysm (TAA) where haemodynamic stresses on the diseased aortic wall are thought to lead to the growth, progression and rupture of the aneurysm. Based on MR images, a patient-specific TAA model was reconstructed. A newly developed two-equation laminar-turbulent transitional model was employed and realistic velocity and pressure waveforms were used as boundary conditions. Analysis of results include turbulence intensity, wall displacement, WSS, wall tensile stress and comparison of velocity profiles between MRI data, rigid and FSI simulations. Velocity profiles demonstrated that the FSI simulation gave better agreement with the MRI data while results for the time-averaged WSS (TAWSS) and oscillatory shear index (OSI) distributions showed no qualitative differences between the simulations. With the FSI model, the maximum TAWSS value was 13% lower, whereas the turbulence intensity was significantly higher than the rigid model. The FSI simulation also provided results for wall mechanical stress in terms of von Mises stress, allowing regions of high wall stress to be identified.