Particle deposition in systems of repeatedly bifurcating tubes.

Deposition of half-micron particles from steady inspiratory flows was measured in the daughter branches of the second bifurcations in a symmetric airway model consisting of two successive generations of bifurcation. Two different configurations were studied: (1) both bifurcations in the same plane and (2) the second bifurcation normal to the plane of the first. The results indicate that the deposition in the daughter branches in configuration (2) is relatively uniform, while that in configuration (1) has a distinct second deposition hot spot, in addition to the one at the carinal ridge. The deposition velocities in the branch which has secondary flows in the opposite sense to those in its parent branch are about 50% lower than those in other types of branches. The deposition patterns are consistent with the observed flow profiles in these tubes.