Pressure Change and Gas Mixing Induced by Oscillations in a Closed System

[+] Author and Article Information
D. Isabey

Inserm U. 68, Physiopathologie Respiratoire, Hôpital St-Antoine, Paris, France

A. Harf

Laboratoire de Physiologie, Hôpital Henri Mondor, Créteil, France

H. K. Chang

McGill University, Montreal, Quebec, Canada

J Biomech Eng 107(1), 68-76 (Feb 01, 1985) (9 pages) doi:10.1115/1.3138523 History: Received September 06, 1983; Revised August 09, 1984; Online June 15, 2009


In an attempt to delineate some mechanical behaviors found in branching airways, pressure transmission, gas motion, and mixing were studied during high-frequency oscillation (HFO) in an idealized system consisting of a large straight tube and a rigid sphere linked together by a small straight tube. Depending on the frequency f , and on the unsteadiness dimensionless parameter α, pressure amplitude in the large tube is either strongly attenuated or amplified in the sphere. This finding may provide a theoretical basis for the pressure resonance phenomenon observed in the lung by previous investigators. Gas compression in the closed volume causes convective mixing throughout the system. The measured dispersion was found to be proportional to f(VT /A)2 , in agreement with a recent report. However, bulk convective mixing was sufficient to explain the dispersion for oscillatory volumes (VT ) as small as 80 percent of the small tube volume, as has been previously suggested.

Copyright © 1985 by ASME
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