Numerical Simulation of Particle Behavior in a Bifurcated Channel with Asymmetric Flow Distribution

In recent years, inhalation therapy has become the standard treatment for chronic obstructive pulmonary disease (COPD). To enhance the effect of inhalation therapy, the effective deposition of drug particles into the affected area is required. Numerous simulations have been conducted on particle deposition within the airways of the lung. A one-way coupling scheme is often used in computational methods to reduce computational costs; however, to consider the effect of finite particle sizes, a two-way coupling scheme is required. This scheme includes both fluid-particle interactions and considers the Magnus effect, Saffman lift, and wall effect. By taking lift forces into account, particle migration in the direction perpendicular to the flow may be captured. In this study, we examined the flow and particle distribution at bifurcations using a two-way coupling scheme, particularly in environments where the inertial effects acting on particles cannot be neglected. A two-dimensional symmetric bifurcated channel was used as the calculation model. The regularized lattice Boltzmann method was applied as the governing equation for the flow field and the virtual flux method was used to represent the two-dimensional bifurcated channels and particles. A flow field characterized by an asymmetric flow distribution was reproduced and the particle behavior within this field was evaluated. The results indicated that because of particle migration, the particle crossed the boundary line that divides the flow rate distribution between the two bifurcated channels. This suggests that discrepancies may occur between flow and particle distribution at the bifurcation in environments where inertial effects cannot be neglected.