Numerical study on oscillatory flow in multi-bifurcation of avian lung model

Mechanisms of unidirectional flow generation and gas transport enhancement in an oscillatory flow of avian lungs were numerically studied with a bifurcation model of avian trachea. A model of multi-bifurcating tubes, which has four T-bifurcations, was adopted for the numerical simulation based on SIMPLE and CIP methods. Main concern was placed on the effects of multi-bifurcation geometry on unidirectional flow generation and axial gas transport enhancement. Compared with the previous results with a right-angled branched tube, the magnitude of non-zero mean flow velocity was enhanced. Axial gas transport efficiency, which is defined as a volume ratio of expired fresh gas from a main tube to the inspired fresh gas from a primary tube, became 1.2 times larger than that in a right angled-branched tube.