We computationally investigate the unsteady pulsatile propagation of a finger of air through a liquid-filled rigid cylindrical tube. This study is relevant to acute respiratory distress syndrome (ARDS), which is characterized by pulmonary airway collapse and fluid occlusion. Subsequent airway reopening, driven by mechanical ventilation, may generate damaging mechanical stresses on the airway walls that can result in ventilator-induced lung injury (VILI). We hypothesize that unsteady flows accompanied by dynamic surfactant transport may reduce the incidence of VILI. Herein we investigate the flow-field under constant surface tension to develop a fundamental understanding of unsteady flows in this system, and to identify the parametric ranges over which transport may be optimized to minimize pulmonary atelectrauma.
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