Reduced order modeling for vortex structures in the human upper respiratory tract

Intra-airway vortices formed during inhalation can modulate particle transport in the respiratory tract. This work focuses on the glottic region, the site of the strongest vortex activity during inhalation. Two variants of a CT reconstruction are considered: one representing a healthy airway and the other with a tumor at the glottis. Analyzing the latter helps identify the impact of local geometric perturbations. High-fidelity LES modeling is performed in both variants, simulating moderate inhalation at 30 L/min; inhaled particles between 1–30 microns are also tracked against the ambient flow field. To gain parametric insight into the geometry-flow interaction, a reduced-order model (ROM) is then constructed using 2D potential flow with embedded point vortices; their locations and strengths are guided by the simulated data. The width and spatial orientation of the ROM channel are also informed by medical imaging. The ROM captures the influence of local geometric changes on particle dynamics and identifies the particle size range most affected by vortex structures, consistent with simulations. The results also indicate that particle transport is primarily governed by the strength and centroidal position of dominant vortex regions, rather than detailed characteristics of the flow.