Modeling the effect of vorticity on inhaled transport in the upper airway

TL;DR

This study presents a simplified two-dimensional model to estimate how vorticity influences particle transport in the upper airway, aligning well with full-scale simulations and highlighting the impact of geometry and particle size.

Contribution

The paper introduces a reduced-order model that captures vorticity effects on inhaled particle transport using only net vorticity strength and location, simplifying complex 3D airflow analysis.

Findings

Vorticity significantly affects particle transport in the upper airway.

The reduced-order model accurately predicts transport changes compared to full simulations.

Geometry distortions alter airflow and particle trajectories in predictable ways.

Abstract

Localized vortices can have significant influence on transport of inhaled particles through the upper respiratory tract. These vortices have complex three-dimensional structure with details dependent on the anatomical geometry. Using a highly simplified model, we demonstrate that changes in transport characteristics with geometric distortion can be estimated by accounting merely for the net strength and location of the vorticity in a two-dimensional projection. Test cases consider 30 L/min inhaled airflow containing suspended spherical water droplets from 1 micrometer to 30 micrometers in diameter through (1) a healthy upper respiratory tract and (2) a distorted variation mimicking a glottic tumor. The reduced-order model approximates the system by a two-dimensional potential flow with embedded point vortices having features derived from Large Eddy Simulations of inhaled airflow through anatomically realistic, tomography-based, three-dimensional tracts. The effects of vorticity and particle size on changes in particle transport are shown to be consistent between the reduced-order model and the full-scale simulations.