title: Streamline crossing: An essential mechanism for aerosol dispersion in the pulmonary acinus.
abstract: The dispersion of inhaled microparticles in the pulmonary acinus of the lungs is often attributed to the complex interplay between convective mixing, due to irreversible flows, and intrinsic particle motion (i.e. gravity and diffusion). However, the role of each mechanism, the exact nature of such interplay between them and their relative importance still remain unclear. To gain insight into these dispersive mechanisms, we track liquid-suspended microparticles and extract their effective diffusivities inside an anatomically-inspired microfluidic acinar model. Such results are then compared to experiments and numerical simulations in a straight channel. While alveoli of the proximal acinar generations exhibit convective mixing characteristics that lead to irreversible particle trajectories, this local effect is overshadowed by a more dominant dispersion mechanism across the ductal branching network that arises from small but significant streamline crossing due to intrinsic diffusional motion in the presence of high velocity gradients. We anticipate that for true airborne particles, which exhibit much higher intrinsic motion, streamline crossing would be even more significant.
authors.affiliation: Department of Biomedical Engineering, Technion - Israel Institute of Technology, 32000 Haifa, Israel.
authors.forename: Rami
authors.initials: R
authors.lastname: Fishler
authors.affiliation: Department of Biomedical Engineering, Technion - Israel Institute of Technology, 32000 Haifa, Israel.
authors.forename: Yan
authors.initials: Y
authors.lastname: Ostrovski
authors.affiliation: Department of Biomedical Engineering, Technion - Israel Institute of Technology, 32000 Haifa, Israel.
authors.forename: Chao-Yi
authors.initials: CY
authors.lastname: Lu
authors.affiliation: Department of Biomedical Engineering, Technion - Israel Institute of Technology, 32000 Haifa, Israel. Electronic address: sznitman@bm.technion.ac.il.
authors.forename: Josué
authors.initials: J
authors.lastname: Sznitman
mesh_terms: D000336:Aerosols; D004058:Diffusion; D006112:Gravitation; D008168:Lung / Q000502:physiology*; D044085:Microfluidics; D008954:Models, Biological
chemical_list: D000336:Aerosols
keywords: Inhaled aerosol; Lungs; Microfluidics; Particle dispersion; Pulmonary Acinus; Tracking velocimetry