Research Projects

Respiratory diseases like COVID-19, the common cold, tuberculosis, and influenza are primarily spread through fluid particles expelled from the infected person during expiratory events. Human airways are lined by a mucus layer and saliva, with exhaled fluid particles originating from these layers. Two known physical mechanisms involved in fluid particle formation are turbulent aerosolisation and the breakage of a fluid film during the reopening of an airway. The difference between ocean spray generation and turbulent aersolisation in the oral cavity and airways is due to the shear-thinning viscoelastic nature of the saliva and mucus, flow geometry, and deformability of the muscles supporting these fluids. Previous studies assumed a planar flow geometry applicable to the oral cavity, but a cylindrical flow geometry would be more appropriate for the airways, potentially leading to additional instabilities. Gravity, the cilia layer, and the nonuniform nature of the epithelium layer were also neglected. Previous studies based on linear stability analysis have neglected the role of gravity, the cilia layer, and the nonuniform nature of the epithelium layer. The proposed project aims to fill this gap by analyzing the various instabilities responsible for fluid particle formation. The study will use standard linear stability analysis to derive thin-film equations, which will be used for weakly nonlinear analysis and nonlinear simulations. The predictions could be used to develop strategies to reduce fluid particle formation during expiratory events and provide a guideline for medicine development to reduce fluid particle formation.