| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 93 === Numerical approaches were performed to simulate the particle motions in bifurcated lung airways and phenomena of pulmonary.Nondimensional parameters, Reynolds number and Womersley number, were used to observe effects breathing patterns on pulmonary efficiency and particle motions.When we observe pulmonary phenomena in airways in a breath cycle(T), separation regions formed on the side walls of the bifurcations were observed between T/4 and T/2 during inspiration.
The incoming O2 was carried to the regions near inner walls of the bifurcations.During expiration, separation regions formed at two different places were observed between 3T/4 and T.The first one was found at the intersection between daughter and parent tubes, and the other one appeared downstream in the regions near the side walls of bifurcations.Some of O2 were trapped in the separation regions.
Subsequently, in the next inspiration, the trapped O2 was carried further downstream the alveoli.
Comparing the pulmonary efficiency among different breathing condition, we found that, increasing respiratory volume could enhance the breathing efficiency.However, decreasing oscillation frequency may also improve the breathing efficiency.Comparing the particle deposition efficiency among a variety of breathing condition, it was found that a few of particles deposit on the intersection surface between parent and daughter tubes and the surface of bifurcations.Decreasing in breathing frequency could improve the particle deposition efficiencies.Nonethless, decreasung respiratory volume may enhance the particle deposition efficiency.
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