Effect of particle inlet distributions on deposition in a triple bifurcation lung airway model.

Considering a triple bifurcation as a representative lung airway model of the upper bronchial tree, the effect of different random inlet particle distributions on deposition patterns and efficiencies have been numerically analyzed. The steady laminar three-dimensional transport equations for a dilute micron-size particle suspension have been solved using a commercial finite-volume code with user-enhanced programs. Particle release positions were assigned employing a random number generator following random-parabolic, random-uniform, and random-random distribution functions. Via back tracking, starting positions of all depositing particles were determined for each particle release distribution, including a deterministic-parabolic one which served as a base case. The results indicate that: (1) The starting regions of the depositing particles in a given bifurcation are fixed for the same inlet Reynolds number and Stokes number combination, regardless of the type of distribution profile. The situation for the particle deposition patterns is somewhat similar. However, the type of distribution of inlet particles strongly influences the particle deposition efficiencies. (2) Values of particle deposition efficiencies are very close for the same (parabolically) distributed deterministic versus random inlet particles when all other conditions are fixed. (3) According to the simulation validations, a determinstic parabolic distribution of inlet particles may be sufficient for laboratory data comparison purposes, but random distributions should reflect realistic environmental or medical aerosol inhalation more accurately.