Anatomy matters: the role of the subject-specific respiratory tract on aerosol deposition — a CFD study

Wedel, J., Steinmann, P. , Štrakl, M., Hriberšek, M., Cui, Y. and Ravnik, J. (2022) Anatomy matters: the role of the subject-specific respiratory tract on aerosol deposition — a CFD study. Computer Methods in Applied Mechanics and Engineering, 401(Part A), 115372. (doi: 10.1016/j.cma.2022.115372) (PMID:35919629) (PMCID:PMC9333481)

Abstract

The COVID-19 pandemic is one of the greatest challenges to humanity nowadays. COVID-19 virus can replicate in the host’s larynx region, which is in contrast to other viruses that replicate in lungs only, i.e. SARS. This is conjectured to support a fast spread of COVID-19. However, there is sparse research in this field about quantitative comparison of virus load in the larynx for varying susceptible individuals. In this regard the lung geometry itself could influence the risk of reproducing more pathogens and consequently exhaling more virus. Disadvantageously, there are only sparse lung geometries available. To still be able to investigate realistic geometrical deviations we employ three different digital replicas of human airways up to the 7 th level of bifurcation, representing two realistic lungs (male and female) as well as a more simplified experimental model. Our aim is to investigate the influence of breathing scenarios on aerosol deposition in anatomically different, realistic human airways. In this context, we employ three levels of cardiovascular activity as well as reported experimental particle size distributions by means of Computational Fluid Dynamics (CFD) with special focus on the larynx region to enable new insights into the local virus loads in human respiratory tracts. In addition, the influence of more realistic boundary conditions is investigated by performing transient simulations of a complete respiratory cycle in the upper lung regions of the considered respiratory models, focusing in particular on deposition in the oral cavity, the laryngeal region, and trachea, while simplifying the tracheobronchial tree. The aerosol deposition is modeled via OpenFOAM\protect \relax \special {t4ht=®} by employing an Euler-Lagrangian frame including steady and unsteady Reynolds Averaged Navier–Stokes (RANS) resolved turbulent flow using the k--SST and k--SST DES turbulence models. We observed that the respiratory geometry altered the local deposition patterns, especially in the laryngeal region. Despite the larynx region, the effects of varying flow rate for the airway geometries considered were found to be similar in the majority of respiratory tract regions. For all particle size distributions considered, localized particle accumulation occurred in the larynx of all considered lung models, which were more pronounced for larger particle size distributions. Moreover, it was found, that employing transient simulations instead of steady-state analysis, the overall particle deposition pattern is maintained, however with a stronger intensity in the transient cases.

• Item Type: Articles
• Additional Information: The authors thank the Deutsche Forschungsgemeinschaft, Germany for the financial support in the framework of the project STE 544/58-2 and the Slovenian Research Agency and the Ministry of Science and Technology of China for the support of the bilateral research project BI-CN/20-22-002.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Steinmann, Professor Paul
• Authors: Wedel, J., Steinmann, P., Štrakl, M., Hriberšek, M., Cui, Y., and Ravnik, J.
• College/School: College of Science and Engineering > School of Engineering > Infrastructure and Environment
• Journal Name: Computer Methods in Applied Mechanics and Engineering
• Publisher: Elsevier
• ISSN: 0045-7825
• ISSN (Online): 1879-2138
• Published Online: 28 July 2022
• Copyright Holders: Copyright © 2022 Elsevier B.V.
• First Published: First published in Computer Methods in Applied Mechanics and Engineering 401(Part A): 115372
• Publisher Policy: Reproduced in accordance with the publisher copyright policy