Reciprocating pipe flows as a model of high-frequency ventilation

High-frequency ventilation is a strategy primarily used to provide oxygen to neonatal patients in intensive care. Here, a simple model of the reciprocating flow in a straight pipe with a free end exiting into a large reservoir is examined to investigate some of the fluid mechanics present during high-frequency ventilation. The resulting recirculating mean flow is quantified in terms of the amount of mean recirculating flux and the distance from the free end to which this recirculation penetrates.