Fluid Flow and Particle Transport in Upper Airway Model: With and Without Stenosis

In contemporary society, there is a strong belief that Particulate Matter (PM) has been recognized as the major factor contributing to health problems, particularly for small particles less than 10 µm . Especially, when it comes to Chronic Obstructive Pulmonary Disease (COPD), which is also known as stenosis airway, these diseases probably affect the flow field structure and particle deposition due to its inflammation, leading to the narrowing or obstructive section in the airways. Consequently, the interest in studying the impacts of stenosis on the human airway has been found in many studies. Following this consideration, this study aims to investigate flow field structure and particle deposition in symmetrical human upper airway models with and without stenosis by conducting Computational Fluid Dynamic (CFD) simulations based on the ANSYS FLUENT solver with the application of the hybrid mesh generation technique. Based on Weibel’s [1963. Morphometry of the Human Lung. New York Academic Press, Springer, Berlin.], the airway models are constructed from the trachea to the fourth generation with and without a narrowing section. These simulations are implemented with three different flow rates; which are 7.5 lpm, 15 lpm and 30 lpm; and various particle diameters which are 1 µm, 2.5 µm, 5 µm, 10 µm . The stenosis sections are assumed to be 50% and located at G1 right branch, G2 right branch, G3 left branch for three constructed models respectively. The results from the simulations reveal that the stenosis section highly creates dramatic influences on downstream generations. Moreover, more particles tend to move and get deposited at the unobstructed branch than the obstructed branches. Ultimately, the flow field structures involving velocity, pressure drop, and turbulence intensity are influenced by the stenosis section.