Fig. 5.

Secant distance used as surrogate quantification of airway obstruction along with fold number. In contrast to regular cylindrical geometries with a constant wavelength, the distance between two neighboring folds differs in irregular patient-specific geometries. Here, we use the average secant distance and the associated fold number to quantify the potential for airway obstruction. Red, green, and blue planes correspond to locations where the secant distance and fold number are measured in Y-branch I.