Multiphase dynamics in a three dimensional branching network

Abstract

Abstract The article aims at understanding the complex unsteady fluid dynamics in six generations of a human bronchial tree, which comprises of 63 straight sections and 31 bifurcation modules in a complete breathing cycle. The effects of 3-D arrangement on oscillatory flow is analyzed. Unsteady effects are maximum during the shift of expiration to inspiration and vice versa. It is also observed that the symmetry of the flow in cased of fully developed flow is destroyed due to unsteady effects. The flow division at the bifurcations causes a large asymmetry in the flow field during the inspiration than during the expiration process at the same cross-sections, thus displaying irreversibility of fluid dynamics. The second part of the study is aimed at analyzing the multiphase fluid dynamics inside a six generation bronchial tree for the case of an active smoker. Both the velocity magnitude contours and volume fractions of air and smoke is analyzed and it is observed that the general symmetry of the flow in the main two halves of the branching network is lost due to the interaction of smoke and air in the branches during inhalation and exhalation. It is also observed that higher mass of smoke is accumulated within the daughter branches which are at a lesser angular deviation with the trachea, whereas the branches at the extreme ends have little to no smoke deposit. This phenomenon can be attributed to the high smoke particulate density compared to that of air.