A review of integrative modelling approaches for ciliary dynamics and mucociliary clearance in respiratory tract

Motile cilia in the respiratory tract generate coordinated beating patterns that drive fluid flow and enable efficient mucociliary clearance. Based on their general structural characteristics, cilia exhibit diverse behaviors under complex hydrodynamic and mechanical interactions. Therefore, this overview reports the latest advances in ciliary biology, covering the most fundamental aspects of ciliary structure, metachronal wave generation, and ciliary beating dynamics. Among the three main modeling frameworks for ciliary propulsion, the single and multicilium mechanical models, ciliary layer and airway surface liquid models, and volume-force models correspond to different modeling styles. From this set of models, we describe the mechanics of tracheobronchial mucus transport and outline contributions from Slender Body Theory, Computational Fluid Dynamics, and other advanced fluid-dynamics modeling approaches. Continuum models of viscoelastic and shear-thinning fluids deserve attention, given their relevance for simulating a realistic respiratory environment. Some future phenomena, including synchronized ciliary beats and metachronal wave propagation, are discussed in light of current modeling efforts that fall short of capturing all the aspects of ciliary function. The review continues by discussing future directions for an integrated approach, filling gaps in modeling efforts through a greater understanding of ciliary transport to improve respiratory health and the treatment of diseases.