### Abstract

Analysis of gas transport in oscillatory flow though an airway model with complex geometry such as a single bifurcation, relies on the theoretical understanding of gas exchange during High-frequency oscillation; HFO. Our purpose was to develop a method for measuring the mean effective diffusivity in an oscillatory flow between two points, by applying Laplace Transform Method. The measurement time T_{max}, which is the area of the Laplace integration, and the Laplace parameter s are related to the accuracy of the measured effective diffusivity, D_{eff}. In this study, numerical analysis was carried out to investigate the Laplace Transform Method. We defined the parameter K required to obtain optimum s, and found that K ≅ 0.1. Then we applied this method to evaluate D_{eff} in a straight tube and a single symmetrical bifurcation. The theoretical results for a straight tube agreed with the measured D_{eff}. D_{eff} for the bifurcating tube was greater than that for the straight tube by a factor of Dn^{2}/α^{4}, that proved the effect of the secondary flow.

Original language | English |
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Pages (from-to) | 3860-3866 |

Number of pages | 7 |

Journal | Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B |

Volume | 62 |

Issue number | 603 |

Publication status | Published - 1996 Nov |

### ASJC Scopus subject areas

- Mechanical Engineering

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## Cite this

*Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B*,

*62*(603), 3860-3866.