Numerical Analysis of Air Flow in Dichotomous Respiratory Channel with Asymmetric Compliance under HFOV Condition

抄録

Gas flow in high frequency oscillatory ventilation (HFOV) was numerically investigated. This artificial respiration technique has features of low tidal volume and high frequency. Although molecular diffusion appears to be influential in gas transports at lower airways, the effect of flow convection never vanishes. The present paper is aimed to discuss the contribution of flow convection to gas transports in such lower airways and obtain physical understandings of old air evacuation in the lower airways. For calculating flow in the lower region airway, boundary conditions based on compliance and resistance of airways were introduced. The obtained air flows appeared to be laminar and reversible. However, particle trackings revealed that the pathlines deviated slightly from one respiratory cycle to another, envisaging irreversible trajectories. The Lagrangian analysis also manifested the longitudinal gas redistribution characterized by the incoming central flow and the outgoing near-wall flow. Those effects would be accumulated through repetitive respiration, and result in the effective gas mixing in HFOV