### 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 |
---|---|

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 |

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### ASJC Scopus subject areas

- Mechanical Engineering

### Cite this

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

*62*(603), 3860-3866.

**Measurement of axial effective diffusivity in oscillatory pipe flow by Laplace transform method.** / Fujioka, Hideki; Murakami, Tomohiko; Tanishita, Kazuo.

Research output: Contribution to journal › Article

*Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B*, vol. 62, no. 603, pp. 3860-3866.

}

TY - JOUR

T1 - Measurement of axial effective diffusivity in oscillatory pipe flow by Laplace transform method

AU - Fujioka, Hideki

AU - Murakami, Tomohiko

AU - Tanishita, Kazuo

PY - 1996/11

Y1 - 1996/11

N2 - 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 Tmax, which is the area of the Laplace integration, and the Laplace parameter s are related to the accuracy of the measured effective diffusivity, Deff. 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 Deff in a straight tube and a single symmetrical bifurcation. The theoretical results for a straight tube agreed with the measured Deff. Deff for the bifurcating tube was greater than that for the straight tube by a factor of Dn2/α4, that proved the effect of the secondary flow.

AB - 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 Tmax, which is the area of the Laplace integration, and the Laplace parameter s are related to the accuracy of the measured effective diffusivity, Deff. 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 Deff in a straight tube and a single symmetrical bifurcation. The theoretical results for a straight tube agreed with the measured Deff. Deff for the bifurcating tube was greater than that for the straight tube by a factor of Dn2/α4, that proved the effect of the secondary flow.

UR - http://www.scopus.com/inward/record.url?scp=0030287994&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0030287994&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0030287994

VL - 62

SP - 3860

EP - 3866

JO - Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B

JF - Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B

SN - 0387-5016

IS - 603

ER -