Flow analysis of copd effects in human airways

Abstract

Airflow inside human airway is difficult to study experimentally. Therefore, Computational Fluid Dynamics has been used to study Chronic Obstruction Pulmonary Disease (COPD) inside human airways. First and second generation of human airway (trachea and both left and right bronchi) with two COPD at location T2 and L2 of the airway has been constructed and simulated by numerical method. Obstruction at each location of COPD has been varied for four sizes; 20 percent, 40 percent, 60 percent and 80 percent of the airways diameters. Laminar flow with Re = 1710 and turbulent flow with Re = 5000 with velocity inlet boundary condition were used. Pressure redistribution, velocity redistribution and fluid shear stress analysis has been observed. Both constrictions gave significant effect to the airflow inside the human airway. The correlation of these parameters plotted. For Case 1, the G2.2 region experienced velocity increase as the Tumour at L2 grows. For up to 60 percent growth of airway diameter, the velocity correlation shows a slow velocity increment. However, tumor growth above this value results in high velocity increase. Pressure distribution at the G1 to G2.2 bifurcation was observed to increase due to momentum effect of the Tumour at inlet location L2. Fluid shear stress correlation at tip of Tumour was observed to increase nonlinearly. Case 2 shows the significant pressure drop after the Stenosis at location T3. Stenosis with 80 percent diameter shows the highest pressure drop downstream. Fluid shear stress increased drastically in 80 percent of Stenosis diameter in parallel to the velocity increase and area decrease. In comparison of both COPD, Case 1 (Tumour) produce less peak pressure effect of 101329.5 Pa compare to 102000 Pa for Case 2 (Stenosis). Fluid shear stress and velocity effect was also higher in Case 2 compared to Case 1.It is observed Case 1 produces more serious COPD effect compared Case 2.