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CFD analysis of mucus bridge instability and breakup in the vocal folds

Martin Heinrich*

Michael Döllinger

Rüdiger Schwarze

  • *Contact author: martin.heinrich@imfd.tu-freiberg.de
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Phys. Rev. Fluids 11, 023103 – Published 27 February, 2026

DOI: https://doi.org/10.1103/qq23-l918

Abstract

The atomization of airway mucus during speech represents a primary mechanism for respiratory aerosol generation, which is central to airborne pathogen transmission. While extensive research has examined single-phase phonation aerodynamics, the multiphase dynamics of droplet formation has received less attention. This study aims to fill this critical gap by presenting a multiphase computational fluid dynamics (CFD) model of the human vocal folds. The dynamic formation and subsequent breakup of the mucus bridge are simulated using a volume-of-fluid method coupled with an analytical model describing the time-dependent shape of the glottal orifice. The investigation reveals that initial, small-scale stochastic perturbations on the mucus surface are essential for triggering a physically realistic, multimodal breakup, in contrast to the delayed, symmetric rupture observed in idealized smooth-film simulations. During vocal-folds opening, the bridge thickness exhibits exponential decay rupturing after 2.32ms at a dynamic aspect ratio of approximately 20, a value significantly exceeding the static stability limit. Furthermore, a parametric study reveals that increasing transglottal pressure from 491Pa to 1472Pa, corresponding to louder phonation, accelerates the thinning process and leads to earlier initial rupture after 2.04ms. This work provides fundamental insights into the precursors of respiratory aerosol generation

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Phys. Rev. Fluids 11, 023103– Published 27 February, 2026
  • Received 25 August 2025
  • Accepted 13 January 2026
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