Nanoparticle transport and deposition in bifurcating tubes with different inlet conditions

Transport and deposition of ultrafine particles in straight, bent and bifurcating tubes are considered for different inlet Reynolds numbers, velocity profiles, and particle sizes, i.e., 1 nm⩽dp⩽150 nm. A commercial finite-volume code with user-supplied programs was validated with analytical correlations and experimental data sets for nanoparticle depositions, considering a straight tube, a tubular 90° bend, and a G3-G5 double bifurcation with both planar and nonplanar configurations. The focus is on the airflow structures as well as nanoparticle deposition patterns and deposition efficiencies, which were analyzed for planar and nonplanar bifurcating lung airway models representing part of the upper bronchial tree. Deposition takes place primarily by Brownian diffusion, and thus deposition efficiencies increase with decreasing nanoparticle size and lower inlet Reynolds numbers. Deposition in the nonplanar configuration differs only slightly from that in the planar configuration. When compared with axisymmetric inlet conditions, the more realistic, skewed inlet velocity and particle profiles generate nearly axisymmetric deposition patterns as well. This work may elucidate basic physical insight of ultrafine particle transport and deposition relevant to environmental, industrial and biomedical studies.