CHARACTERISTICS OF INERTIAL DEPOSITION IN A DOUBLE BIFURCATION

A direct numerical simulation of air flow and particle motion is condu cted for doubly bifurcated models in order to see the effect of the ve locity profile distorted by the previous bifurcation on particle depos ition, because particle deposition in a bifurcated airway is very sens itive to the velocity profile at the inlet, not the magnitude. Flow fi elds are solved using the FIDAP, an FEM code, and particle trajectorie s are obtained by a Lagrangean integration. Characteristics of air how and particle motion in double bifurcations are quite different from w hat can be imagined based on results for single bifurcation models. Th e distorted velocity profile can reduce deposition efficiency in the s econd generation by about 50% when compared with the single bifurcatio n for the same Stokes number. The bifurcation geometry is also importa nt for particle deposition, and the out-of-plane rotated geometry give s about 40% higher deposition than the in-plane bifurcations.