分岐管ネットワークにおける往復流による管軸方向物質輸送 : ヒトの肺の誘導気道におけるガス交換機構(熱工学,内燃機関,動力など)

Flow visualization in reciprocating flow inside a three-generation branching-tube network was performed to investigate the mechanism of axial gas exchange in conducting airways of human lung system. Water was used as the working fluid and nondiffusing dye was employed as tracer. The ranges of Reynolds and Womersley numbers at the 0-th generation tube were 60-6000 and 5-25, respectively. It was revealed that bi-directional axial gas-exchange phenomenon occurring in the conductive airways of human lung system was governed by "trap-and-release" mechanism caused by the formation-and-destruction of the separation regions. In inspiration process, separation regions were formed on the outside wall of the two daughter tubes, while they were generated on both (1) the outside wall of the parent tube and (2) the intersection circumference of the two different diameter tubes, or parent and daughter tubes.