TY - JOUR
T1 - Evaluation of local gas transport rate in oscillatory flow in a model of human central airways
AU - Tanaka, Gaku
AU - Ito, Jin
AU - Oka, Kotaro
AU - Tanishita, Kazuo
PY - 1997/6
Y1 - 1997/6
N2 - The rate of local axial gas transport in oscillatory flow through a model of human central airways was measured to evaluate gas exchange during high-frequency oscillation. A rigid model of human central airways consists of asymmetrical bifurcations up to 3-5 generation, of which geometries were determined by the study of Horsfield et al. A bolus of CO2 tracer was injected into the trachea, and effective diffusivities as a function of location in the airways were obtained from CO2 washout profiles. The rate of increase of effective diffusivity depends on the local flow conditions and differs with branches. The effective diffusivity in the left main bronchus is 3.2 times greater than that in the straight tube, whereas no significant difference is observed in the right main bronchus. In addition, the presence of a stationary period augments axial gas transport in intermittent oscillatory flow because it provides time for the occurrence of lateral mixing in the radial direction, i. e., axial diffusivity is 1.6 times greater on the average than that in sinusoidally oscillatory flow.
AB - The rate of local axial gas transport in oscillatory flow through a model of human central airways was measured to evaluate gas exchange during high-frequency oscillation. A rigid model of human central airways consists of asymmetrical bifurcations up to 3-5 generation, of which geometries were determined by the study of Horsfield et al. A bolus of CO2 tracer was injected into the trachea, and effective diffusivities as a function of location in the airways were obtained from CO2 washout profiles. The rate of increase of effective diffusivity depends on the local flow conditions and differs with branches. The effective diffusivity in the left main bronchus is 3.2 times greater than that in the straight tube, whereas no significant difference is observed in the right main bronchus. In addition, the presence of a stationary period augments axial gas transport in intermittent oscillatory flow because it provides time for the occurrence of lateral mixing in the radial direction, i. e., axial diffusivity is 1.6 times greater on the average than that in sinusoidally oscillatory flow.
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M3 - Article
AN - SCOPUS:0031170417
SN - 0387-5016
VL - 63
SP - 1946
EP - 1954
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
IS - 610
ER -