Background: Nasal obstruction (NO) is a very common symptom, but its effect on nasal physiology has not been fully understood. We performed this study to determine the effect of severity of NO due to inferior turbinate hypertrophy on airflow pattern using the computational fluid dynamics simulations. Methods: A three-dimensional nasal cavity model was constructed from the MRI scans of a healthy human subject. Nasal cavities corresponding to healthy, moderate, and severe NO was simulated by enlarging the inferior turbinate geometrically, which can be documented by approximately one-third reduction of the minimum cross-sectional area (1.453 cm ² in the healthy nose) for the moderate (0.873 cm ² ) and two-thirds (0.527 cm ² ) for the severe obstruction. Results: Total negative pressure through the nasal cavity increased during the inspiratory phase by almost twofold (-19 Pa) and threefold (-33 Pa) for moderate and severe blockage, respectively, compared with the increase of total negative pressure of -10 Pa in a healthy nose. In cases of moderate and severe blockage, a higher velocity and shear stress was observed at the nasopharynx and dorsal region of the nasal cavity. Moreover, nasal valve function will not exist in severe NO because of the changes of airflow pattern at the original nasal valve location. Conclusion: Impairment of nasal airflow and physiology is evidenced in NO caused by inferior turbinate hypertrophy. Data of this study may help in predicting the aerodynamic effects of surgical correction of the inferior turbinate hypertrophy.