The respiratory tract of mammals is lined with a layer of mucus, described as a viscoelastic semi-solid, above a layer of watery serous layer. For a healthy person, rhythmic beating action of cilia propels the mucus layer continually. Dehydration results in the disappearance of serous layer and impairs the mucociliary clearance. These persons must relay on the two-phase gas-liquid flow and cough as the clearance mechanism. In this study, the interaction of airflow with a mucus simulant in a channel is investigated experimentally. Locust Bean Gum and Borax dissolved in deionized water is used as the mucus simulant. Two types of instability mechanisms are observed. The first is the propagating waves that appear at relatively low air speed and the catastrophic clearance that resembles an avalanche. The results show that onset flow speeds for both instabilities are sensitive to the layer thickness and decrease with the increasing thickness. Onset for the clearance does not seem to be sensitive to the viscoelastic properties of the mucus simulant.

This content is only available via PDF.
You do not currently have access to this content.