Interaction of airflow with a viscoelastic mucus simulant: An engineering study.

摘要

The study of the air flow interaction with mucus in the human lungs is associated with the study of air flow through a compliant passage lined with viscoelastic airway mucus. Researchers have used different methods to model and simulate this interaction mechanism. The model needs to address the complicated issues of the human mucus properties, complicated geometry and the compliance of the airways.; The objective of this study is to explore effects of different parameters on the clearance of a simulant resembling the viscoelastic behavior of the human mucus under different flow and geometry conditions.; Two types of mucus simulants, with different elasticity and viscosity to elasticity ratio (V/E), are used. The simulant with a lower V/E, and higher elastic modulus may represent the relative change in the mucus behavior for a patient with Obstructive Pulmonary Disease (OPD). The wave initiation on the surface and clearance of simulant layers with different thicknesses subject to air flow in a straight rectangular channel are studied. The results showed that onset air velocity for wave initiation or clearance is reduced by an increasing layer thickness. Also, for the simulant with higher V/E ratio and lower elasticity waves initiate at lower layer thickness and this behavior reverses for higher thickness.; A rigid model of the human trachea was built to explore the effects of different parameters on the cough clearance of a simulant droplet from the human trachea. 0.3 sec pulse with controlled air velocity is used to simulate the cough. The parameters studied included inclination angle, air flow rate, interface condition between the simulant droplet and rigid surface of the trachea model.; The results suggest that the simulant with low V/E is more suitable for clearing by cough due to its high elasticity which helps improve the clearance by maintaining a blunt shape of the droplet during coughing. The results also show an improvement in the cough clearance for 15° inclination angle compared to the horizontal case.