A Numerical Study of Heat and Water Vapor Transfer in MDCT-Based Human Airway Models

作者：Wu Dan; Tawhai Merryn H; Hoffman Eric A; Lin Ching Long^*

来源：Annals of Biomedical Engineering, 2014, 42(10): 2117-2131.

DOI：10.1007/s10439-014-1074-9

• Thermodynamics
• Human airway temperature
• Water vapor
• Computed tomography

A three-dimensional (3D) thermo-fluid model is developed to study regional distributions of temperature and water vapor in three multi-detector row computed-tomography-based human airways with minute ventilations of 6, 15 and 30 L/min. A one-dimensional (1D) model is also solved to provide necessary initial and boundary conditions for the 3D model. Both 3D and 1D predicted temperature distributions agree well with available in vivo measurement data. On inspiration, the 3D cold high-speed air stream is split at the bifurcation to form secondary flows, with its cold regions biased toward the inner wall. The cold air flowing along the wall is warmed up more rapidly than the air in the lumen center. The repeated splitting pattern of air streams caused by bifurcations acts as an effective mechanism for rapid heat and mass transfer in 3D. This provides a key difference from the 1D model, where heating relies largely on diffusion in the radial direction, thus significantly affecting gradient-dependent variables, such as energy flux and water loss rate. We then propose the correlations for respective heat and mass transfer in the airways of up to 6 generations: and , where Nu is the Nusselt number, Sh is the Sherwood number, Re is the branch Reynolds number, D (a) is the airway equivalent diameter, and is the tracheal equivalent diameter.

• 出版日期2014-10