Effects of Temporally-Varying Inlet Conditions on Flow and Particle Deposition in the Small Bronchial Tubes

Soni, B., & Thompson, D. (2012). Effects of Temporally-Varying Inlet Conditions on Flow and Particle Deposition in the Small Bronchial Tubes. International Journal for Numerical Methods in Biomedical Engineering. 28(9), 915-936. DOI:10.1002/cnm.2472.

Abstract

The laminar flow in the small bronchial tubes is quite complex due to the presence of vortex-dominated, secondary flows. Factors contributing to this complexity are the unsteady nature of the inhale-exhale breathing cycle and the geometrical characteristics of the bronchial tubes. To investigate unsteady effects on flows and particle transport, unsteady inhalation flows at a 30-respiration-per-minute frequency, corresponding to a moderate activity level, were simulated for a three-generation, asymmetric, planar bronchial tube model. Ten-micron diameter water droplets were introduced at the inlet at different times during inhalation to develop particle destination maps. The differences in the flow fields and destination maps at the unsteady peak flow and comparable steady-state conditions were minimal. However, particles released at equivalent instantaneous off-peak inflow conditions produced different destination maps. The differences were attributed to the temporal variations of the fluid velocities and history effects.