Numerical simulation of voluntary respiration in a model of the whole human lower airway.

The lung model construction is limited to the local scale, and the numerical simulation of autonomous breathing is mostly computed from top to bottom in recent research. In this study, models of the entire lower airway from G0-G23 were constructed, and computational simulations were performed for the alveolar model using coupled fluid-solid analysis with pressure changes on the wall and for the rigid bronchial model using computational fluid dynamics by transmitting the boundary conditions step from bottom to top. This paper provides the results under spontaneous respiration, including the ventilation volume of the tracheobronchial tree, the situation of the internal flow field, and the mechanical characteristics of the lung tissues. The mechanical characteristics and the lung functions computed by the models were consistent with clinical or experimental data. This model could provide quantitative analysis results of respiratory mechanics in the lower respiratory tract of the human, which offers a reference for mechanical studies, such as the morphological changes and differentiation of cell types induced by force stimulation and tumor induction. Furthermore, various pathological models can be developed based on this model.