Wall shear stress distribution in a compliant airway tree
Abstract
The airflow in the bronchi applies a shear stress on the bronchial mucus, which can move the mucus. The airmucus interaction plays an important role in cough and in chest physiotherapy (CP). The conditions under which it induces a displacement of the mucus are still unclear. Yet, the airmucus interaction justifies common technics of CP used to help the draining of the mucus in prevalent diseases. Hence, the determination of the distribution of the shear stress in the lung is crucial for understanding the effects of these therapies and, potentially, improves their efficiency. We develop a mathematical model to study the distribution of the wall shear stress (WSS) induced by an air flow exiting an airway tree. This model accounts for the main physical processes that determine the WSS, more particularly the compliance of the airways, the air inertia, and the tree structure. We show that the WSS distribution in the tree depends on the dynamics of the airways deformation and on the air inertia. The WSS distribution in the tree exhibits a maximum whose amplitude and location depend on the amount of air flow and on the "tissue" pressure surrounding the airways. To characterize the behavior of the WSS at the tree bifurcations, we derive new analytical criteria related to the airway size reduction in the bifurcations. Our results suggest that a tuning of the airflow and of the tissue pressure during a CP maneuver might allow to control, at least partially, the airmucus interaction in the lung.
 Publication:

Physics of Fluids
 Pub Date:
 March 2021
 DOI:
 10.1063/5.0038706
 arXiv:
 arXiv:2011.09740
 Bibcode:
 2021PhFl...33c1907S
 Keywords:

 Physics  Biological Physics;
 Physics  Computational Physics;
 Physics  Fluid Dynamics;
 Quantitative Biology  Tissues and Organs
 EPrint:
 doi:10.1063/5.0038706