Abstract:
Haribalan Kumar and Benjamin Mauroy Mucus plays an important role in protecting the lungs against external aggressions: it captures alien particles and is continually motioned out of the lung. If mucus transport is altered, then chest physiotherapy (CP) can reduce the risks of mucus stagnation. Cough and CP move mucus by its interaction with air. However, air-mucus interaction in bronchi is not well known. A few years ago, the first mathematical models were proposed with simple modeling hypotheses, assuming flat mucus distributions in the bronchi [1,2]. In this work, we study mucus interaction with air flows that mimic cough or CP. Our goal is to find out how the geometry of the air/mucus interface affects mucus transport. We developed an in silico model of mucus transport in a bronchus using OpenFOAM. Mucus was modeled as a HerschelBulckley fluid. Its interaction with air is modeled with a phase field technique. The model was validated against theoretical results [1]. We tested different sizes of bronchus, mucus thicknesses and amount of air flows. Mimicking exercise, CP and cough regimes, our model predicts mucus motion down to lung’s generations 4, 9 and 15 respectively. Mucus distribution pattern depends on the bronchi size. In small bronchi, mucus tends to form travelling plugs. In larger bronchi, mucus forms a nonflat layer on the wall and is moved in waves, with original behaviors and shapes. Our findings give a detailed description of the biophysical processes affecting mucus motion by air in the bronchi. This modeling approach might help physicians to better understand mucus transport’s pathologies and CP practitioners to get better insights on their techniques. [1] Mauroy et al, Phys Biol, 8(5):056006, 2011. [2] Mauroy et al, Front Physiol, 6:214, 2015.
