Background: The objective analysis of nasal airflow stands to benefit greatly from the adoption of computational fluid dynamic (CFD) methodologies. In this emerging field, no standards currently exist in regard to the ideal modeling parameters of the nasal airway. Such standards will be necessary for this tool to become clinically relevant. Methods: Human nasal airways were modeled from a healthy control, segmented, and analyzed with an in-house immersed boundary method. The segmentation Hounsfield unit (HU) threshold was varied to measure its effect in relation to airflow velocity magnitude and pressure change. Findings: Surface area and volume have a linear relationship to HU threshold, whereas CFD variables had a more complex relationship. Interpretation: The HU threshold should be included in nasal airflow CFD analysis. Future work is required to determine the optimal segmentation threshold.