Property dependence of onset of instability in viscoelastic respiratory fluids

This paper deals with the modelling of viscoelastic respiratory fluids in the mucus layer of the human trachea with a view toward the design of improved inhaled medication. The problem of instability and droplet formation in this layer, specifically aimed at problems of both cough particle suppression as well as reduction of disease transmission, is studied. Rayleigh-Taylor type analysis is performed on the suitably chosen viscoelastic model to investigate temporal instabilities and their relation to the fluid properties. Several physiologically important conclusions are obtained in support of potential treatments that work by adjusting the mucus layer properties. An important result from the analysis shows that the two potential treatment approaches are mutually incompatible.