Purpose: The aim of this study was to evaluate the impact of wall share stress (WSS) in the carotid artery using a computed fluid dynamics analysis system and adopting open-source software. Methods: The dependence of element number (computation time and analytical accuracy) were considered with simple vessel models. We evaluated WSS and flow velocity using a carotid artery model that was based on the outcome of simple vessel models. Results: When the number of elements was 10⁵ or more, the flow velocity error of the outlet decreased to 0.5% or below when using simple vessel models. The carotid bifurcation model showed a whirlpool and a decrease in flow velocity in the carotid bulb part. Conclusion: An analysis system was built using open source software. The results from the carotid bifurcation model suggested that hemodynamics contributes to the development of carotid stenosis.