Surfactant Analysis of Thin Liquid Film in the Human Trachea via Application of Volume of Fluid (VOF)

Abstract

The human tracheobronchial tree is a complex branched distribution system in charge of renewing the air inside the acini which are the gas exchange units. The surfactant factor existing in the acini of the human tracheobronchial tree is exposed to thin liquid film flow where the application of volume of fluid (VOF) can significantly determine the membrane effects on the branching asymmetry. The thin film application in this chapter will focus on the breathing airway which is commonly known as the windpipe (trachea) of an adult human. The upper human airway is the primary conduit for inspiration in the breathing process. Air entering the mouth passes through pharynx and flows into the trachea via the glottal region. The air which enters the windpipe applies a surfactant pressure at the lipoprotein complex, where this complex is developed as a thin layer on the trachea (Caro et al. 2002). The surfactant is a lipo-protein complex, which is a highly surface-active material found in the fluid lining of the air-liquid interface in the trachea surface. This surfactant plays a dual function of preventing sudden collapse during the breathing cycle and protection from injuries and infections caused by foreign bodies and pathogens. The varying degrees of structure-function abnormalities of surfactant have been associated with obstructive trachea diseases, respiratory infections, respiratory distress syndromes, interstitial lung diseases, pulmonary alveolar proteinosis, cardiopulmonary bypass surgery and smoking habits. For some of the pulmonary conditions, especially respiratory distress syndrome, surfactant therapy is on the horizon. In order to understand the behaviour and relevant condition of the surfactant in the human trachea, it is important to apply the volume of fluid method on these surfaces. The phenomena that occur on the trachea will ensure that the surfactant responsibility in resolving the potential obstruction of breathing. The surfactant factor may occur with non-lateral conditions in space as well as during the inspiration of breathing in the human body. The fluid interaction in the thin surface results in serious impairment by obstructive trachea diseases as mentioned earlier. The pulmonary surfactant is essential for normal breathing, alveolar stability and as a host defence system in the lungs. The interface of surfactant films reduces the surface tension to extremely low values when it is compressed during expiration. This protects our lungs from collapse during breathing out. Thus application of the Volume of Fluid (VOF) method is introduced in this paper to study the behaviour of the pulmonary surfactant in the human trachea.