title: A Numerical Study of Water Loss Rate Distributions in MDCT-Based Human Airway Models.
abstract: Both three-dimensional (3D) and one-dimensional (1D) computational fluid dynamics methods are applied to study regional water loss in three multi-detector row computed-tomography-based human airway models at the minute ventilations of 6, 15 and 30 L/min. The overall water losses predicted by both 3D and 1D models in the entire respiratory tract agree with available experimental measurements. However, 3D and 1D models reveal different regional water loss rate distributions due to the 3D secondary flows formed at bifurcations. The secondary flows cause local skewed temperature and humidity distributions on inspiration acting to elevate the local water loss rate; and the secondary flow at the carina tends to distribute more cold air to the lower lobes. As a result, the 3D model predicts that the water loss rate first increases with increasing airway generation, and then decreases as the air approaches saturation, while the 1D model predicts a monotonic decrease of water loss rate with increasing airway generation. Moreover, the 3D (or 1D) model predicts relatively higher water loss rates in lower (or upper) lobes. The regional water loss rate can be related to the non-dimensional wall shear stress (τ (*)) by the non-dimensional mass transfer coefficient (h 0 (*) ) as [Formula: see text].
authors: Department of Mechanical and Industrial Engineering, 2406 Seamans Center for the Engineering Arts and Sciences, The University of Iowa, Iowa City, 52242, Iowa, USA.|Department of IIHR-Hydroscience & Engineering, The University of Iowa, Iowa City, 52242, Iowa, USA.
authors: Dan
authors: D
authors: Wu
authors: Department of IIHR-Hydroscience & Engineering, The University of Iowa, Iowa City, 52242, Iowa, USA.
authors: Shinjiro
authors: S
authors: Miyawaki
authors: Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand.
authors: Merryn H
authors: MH
authors: Tawhai
authors: Department of Biomedical Engineering, The University of Iowa, Iowa City, 52242, Iowa, USA.|Department of Internal Medicine, The University of Iowa, Iowa City, 52242, Iowa, USA.|Department of Radiology, The University of Iowa, Iowa City, 52242, Iowa, USA.
authors: Eric A
authors: EA
authors: Hoffman
authors: Department of Mechanical and Industrial Engineering, 2406 Seamans Center for the Engineering Arts and Sciences, The University of Iowa, Iowa City, 52242, Iowa, USA. ching-long-lin@uiowa.edu.|Department of IIHR-Hydroscience & Engineering, The University of Iowa, Iowa City, 52242, Iowa, USA. ching-long-lin@uiowa.edu.
authors: Ching-Long
authors: CL
authors: Lin
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D006813:Humidity; D057446:Hydrodynamics; D008168:Lung / Q000000981:diagnostic imaging / Q000502:physiology; D008297:Male; D008954:Models, Biological; D012143:Respiratory Physiological Phenomena; D013696:Temperature; D014057:Tomography, X-Ray Computed; D014870:Water Loss, Insensible; D055815:Young Adult
keywords: Computed tomography; Evaporative water loss; Human lung; Shear stress