A computational model that simulates mucociliary clearance in the bronchial tree, and a concomitant study on energetics and optimality

Systemic deterministic models of mucociliary clearance in the bronchial tree are currently scarce. While analytical/computational efforts have focused on microscopic modeling of mucociliary propulsion, macroscopic approaches have been restricted mainly to stochastic methods. We present an analytical/computational model that simulates mucociliary clearance in macroscopic physical domains. The analytical foundations of the model are based on a Stokes flow assumption, whereby, in addition to viscous forces originating in ciliary forcing, the role of surface tension is also considered. The governing equations are solved computationally on a three-dimensional surface mesh. Flow is simulated in an anatomically/geometrically representative bifurcation of the bronchial tree. The directionality of ciliary forcing in our model is optimized in order to maintain near-uniform mucus film thickness throughout the flow field. Based on the optimized version of the model, energetic considerations, as well as aspects of optimality in nature are analyzed and presented.