Reliability of Generic Flow Conditions in Fluid-Structure Interaction (FSI) Modeling of the Internal Carotid Artery

Understanding how blood flows through the internal carotid artery (ICA) is essential, as disturbances in this region are closely linked to atherosclerosis and stroke. Computational modeling, particularly fluidstructure interaction (FSI), has become a valuable tool for studying these processes, but its reliability strongly depends on how inlet flow conditions are defined. This study investigates how simplified, generic inlet conditions influence the prediction of ICA hemodynamics. A fully coupled two-way FSI model was developed, where blood is treated as a non-Newtonian fluid using the Carreau model, and the arterial wall is represented as a deformable elastic structure. Simulations were performed for four heart rates (6690 bpm) and several representative inlet waveforms. Key hemodynamic parametersincluding velocity, pressure, wall shear stress (WSS), time-averaged WSS (TAWSS), oscillatory shear index (OSI), and relative residence time (RRT)were analyzed. Results show that variations in heart rate and waveform shape significantly affect the magnitude of peak velocity, pressure, and WSS. However, these changes have minimal impact on the spatial distribution of hemodynamic indicators. Regions associated with disturbed flow consistently remain localized within the carotid sinus and bifurcation, regardless of inlet conditions. This indicates that arterial geometry plays a dominant role in determining the location of atheroprone regions, while inlet conditions mainly influence their intensity. Overall, generic inlet conditions may be sufficient for qualitative identification of high-risk regions, but accurate, patient-specific inflow data are necessary for reliable quantitative predictions.