Numerical study of nanoparticle penetration characteristics in forked tubes using tracking particle identification

The objective of this study was to investigate the penetration characteristics of sub-100 nm nanoparticles in a forked tube with a tree-like branching structure at Reynolds numbers ranging from 370 to 2000. A modified single-particle tracking analysis based on the aerosol mass flow rate was employed to track individual particles; the particle deposition efficiency was compared with the experimental results to ensure the accuracy of the numerical analysis method. The flow and deposition characteristics of sub-100 nm nanoparticles were systematically analyzed by obtaining the contours of particle distribution, particle concentration, and particle ID on various cross-sections in a forked tube. Based on the results, we found a non-uniform particle concentration, resulting in a particle-free zone after passing a bending point. In addition, we suggested a correlation equation for the deposition efficiency in a forked tube under various conditions, represented by the Peclet number; the equation covers the entire range of tested Reynolds numbers. Furthermore, clear differences in the deposition behaviors between forked, straight, and single sharp-bent tubes were observed. Using a correlation equation for a single-bent tube to determine the deposition efficiency in a forked tube with two consecutive elbow connections overestimated the efficiency because of the non-uniformity of the particle distribution after the particles passed the first elbow. The model presented in this work can be expanded further for more complicated tubing systems while providing insights into tracking particle contamination sources in various applications.