Objective To investigate the hemodynamic factors in internal carotid arteries (ICA) with different shapes, and analyze the relationship between the arterial geometry and atherosclerotic stenosis to provide the hemodyanmic basis for the risk prediction and early diagnosis of ICA stenosis. Methods The flow field in the most two common types of ICAs, U and V-shaped ICA, were investigated by numerical simulation and particle image velocimetry (PIV) experiment under the condition of steady flow. Results At the upstream bend of ICA, the hemodynamic factors were monotonically associated with the curvature of the bend. As a result, the risk for stenosis here was smaller in the V-shaped ICA, as compared to U-shaped ICA. But at the downstream bend, such monotonic relationship didn’t exist due to the synergistic effect of the two bends. ConclusionsThe curvature of the artery is positively related to the risk for stenosis, but the synergistic effect of bends needs to be considered for studying arteries with the serial bends. The research on the synergistic effect may explain why the stenosis is frequently observed in arteries with multiple bends.