Class: BE-310
Group: M1
Members: Kevin T Justice, Joanna K Law, Craig Rineer, Kartik Shah
Date: May 4, 1998
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Abstract:
The evolution of the pulmonary tract has gone through a great deal of mechanical and physiological alterations so that the body can maximize the use of the lungs system. A cough is the pressurization of the lungs so that the first few generations of bronchi can effectively have any mucus removed. The purpose of coughing, in this respect, is to prevent viral and other infectious matter from settling in the lungs where the damp environment may encourage foreign growth. In this project, we investigated the mechanical effectiveness of the narrowing of tubes as a means for more effectively removing mucus from the lungs. In a real cough, a person takes a deep breath, closes the glottis and effectively pressurizes the lungs so that a turbulent jet is generated to blow out mucus from the bronchioles and into the trachea. In addition to the pressurizing of the lungs, there is a collapse of the tubes so that with the smaller cross-sectional, a higher velocity may be generated to remove the mucus.

In this project, we investigated two parameters, which differ in the physiological mechanisms of the cough: the differences in pressure and in tube size. The generation of greater pressure for a given tube size will in effect increase the fraction coughed out as does the smaller tube size as a greater force can be generated and transferred to the mucus. With our data, we found smooth curves for each tubing apparatus, which, with an attempted logarithmic fit, found that the smaller tubing apparatus on average removed about 5% more than the larger system for a dimensionless parameter in the range of 1E+06 to 6E+06. Finally, we built an apparatus that is more physiologically realistic with a branching system that represents the second generation of bronchioles. The purpose of this was to investigate the difference in the straight tube apparatus as used during the semester and our apparatus in terms of realism and actual situation in which the branching will affect heat loss and conservation of mass. With respect to the difference in tubing sizes, we found that the larger system coughed out 20% to 29% less than the single tube system while the smaller branching system was 17% to 24% less than the single tube.