Characteristics of inertial deposition in a double bifurcation

A direct numerical simulation of air flow and particle motion is conducted for doubly bifurcated models in order to see the effect of the velocity profile distorted by the previous bifurcation on particle deposition, because particle deposition in a bifurcated airway is very sensitive to the velocity profile at the inlet, not the magnitude. Flow fields are solved using the FIDAP, an FEM code, and particle trajectories are obtained by a Lagrangean integration. Characteristics of air how and particle motion in double bifurcations are quite different from what can be imagined based on results for single bifurcation models. The distorted velocity profile can reduce deposition efficiency in the second generation by about 50% when compared with the single bifurcation for the same Stokes number. The bifurcation geometry is also important for particle deposition, and the out-of-plane rotated geometry gives about 40% higher deposition than the in-plane bifurcations.