Dynamic flow in a realistic model of the upper human lung airways

Dynamic flow in a realistic model of the upper human lung airways The objective of the study is an analysis of lung ventilation during breathing under rest conditions and for high frequency ventilation (HFV). The measurements include investigations of the flow using an endotracheal tube. A transparent model of the upper human lung airways down to the 6th generation was generated, and the oscillatory flow through the branching network was studied by DPIV. The method of refractive index matching of the fluid (water/glycerin) and the model (silicone) allows an unobstructed view into the internal flow network. The mass flow rate and the frequency were adapted to the characteristic flow parameters, the Reynolds- and the Womersley-number. The comparison of the results for normal breathing and HFV shows that a mass exchange occurs for higher frequencies known as Pendelluft, which could not be seen during normal breathing. This mass exchange between the daughter tubes is a consequence of the asymmetric impedance in the successive daughter branches. The lung topology determines the local pressure loss in the model and therefore the local mass flow direction of the Pendelluft. At higher frequencies we observed an increase in exchange between the daughter branches. The transformation of the velocity profiles between inspiration and expiration suggests a net mass flow which is created into the model along the centerline and the inner walls of the bifurcations. This flow is compensated with a net mass outflow to the trachea along the outer walls of the branches. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Experiments in Fluids Springer Journals

Dynamic flow in a realistic model of the upper human lung airways

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Publisher
Springer-Verlag
Copyright
Copyright © 2007 by Springer-Verlag
Subject
Engineering; Engineering Fluid Dynamics; Fluid- and Aerodynamics; Engineering Thermodynamics, Heat and Mass Transfer
ISSN
0723-4864
eISSN
1432-1114
D.O.I.
10.1007/s00348-007-0296-0
Publisher site
See Article on Publisher Site

Abstract

The objective of the study is an analysis of lung ventilation during breathing under rest conditions and for high frequency ventilation (HFV). The measurements include investigations of the flow using an endotracheal tube. A transparent model of the upper human lung airways down to the 6th generation was generated, and the oscillatory flow through the branching network was studied by DPIV. The method of refractive index matching of the fluid (water/glycerin) and the model (silicone) allows an unobstructed view into the internal flow network. The mass flow rate and the frequency were adapted to the characteristic flow parameters, the Reynolds- and the Womersley-number. The comparison of the results for normal breathing and HFV shows that a mass exchange occurs for higher frequencies known as Pendelluft, which could not be seen during normal breathing. This mass exchange between the daughter tubes is a consequence of the asymmetric impedance in the successive daughter branches. The lung topology determines the local pressure loss in the model and therefore the local mass flow direction of the Pendelluft. At higher frequencies we observed an increase in exchange between the daughter branches. The transformation of the velocity profiles between inspiration and expiration suggests a net mass flow which is created into the model along the centerline and the inner walls of the bifurcations. This flow is compensated with a net mass outflow to the trachea along the outer walls of the branches.

Journal

Experiments in FluidsSpringer Journals

Published: Apr 19, 2007

References

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