A Macroscopic Model for Simulating the Mucociliary Clearance in a Bronchial Bifurcation: The Role of Surface Tension

Abstract

The mucociliary clearance in the bronchial tree is the main mechanism by which the lungs clear themselves of deposited particulate matter. In this work, a macroscopic model of the clearance mechanism is proposed. Lubrication theory is applied for thin films with both surface tension effects and a moving wall boundary. The flow field is computed by the use of a finite-volume scheme on an unstructured grid that replicates a bronchial bifurcation. The carina in bronchial bifurcations is of special interest because it is a location of increased deposition of inhaled particles. In this study, the mucus flow is computed for different values of the surface tension. It is found that a minimal surface tension is necessary for efficiently removing the mucus while maintaining the mucus film thickness at physiological levels.

Curvature-induced motion of a thin Bingham layer in airways bifurcations

“…Another way for estimating the velocity wall field was chosen in [20]. However the properties of the field obtained by our method and the properties of the field obtained in [20] are very close.…”

“…The role of the surface tension on the air-mucus interface is however often neglected [19,20]. The surface tension induces a jump of pressure -the Laplace pressure-across a curved interface: ∆p L = 2γκ with γ the coefficient of surface tension and κ the mean curvature of the interface.…”

“…The Reynolds number associated to the mucus in the airways is low and the fluid mechanics is well approximated by the Stokes equations. Then, denoting u the fluid velocity and p its pressure, the momentum and mass [20,27,29] TABLE I. Data range of the parameters of our model and their default values used in this paper, shown between parentheses.…”

“…tree to be tangential to airways walls. The clearance is directed toward the larger airways [20] and has an amplitude of 50 µm [27], see Appendix E. Typical outputs are presented in Fig. 1.…”

Effect of chest physiotherapy on cystic fibrosis sputum nanostructure: an experimental and theoretical approach

“…The viscoelastic nature of mucus depends on the presence of different components such as proteins, alginates, white blood cells, DNA, bacteria and mucin (whose levels are pathologically increased compared with healthy subjects [39]) that lead to a three-dimensional network [40]. Drug permeation inside the ASL is a complex phenomenon affected by many factors such as the thickness of ASL, which depends on the ASL rheological properties and the airflow [37,41,42]. Moreover, possible interactions (e.g.…”