Fig. 1 - adult human tracheobronchial tree.
A parallel, n-fluid CFD solver, NPHASE, is employed in the analyses. The differential models employed are homogeneous n-species (n-gas constituents) and ensemble averaged n-fluid (gas+particle) systems. Specialized boundary conditions have been developed and applied at each of the more than 700 bronchi termini. These boundary conditions account for effective volume variation during a breathing cycle, O2-CO2 exchange, and diffusion range deposition. Convective and diffusive particle deposition models
are also developed and applied for the resolved bronchi.
Predicted oxygen concentration in the wall-adjacent finite volumes at a particular inhalation timestep. (larger image)
Contours of normalized relative helicity at a cut just downstream of the first bronchi branch illustrating the secondary flows present. (larger image)
Composite plot of contours of 16 mm
particle deposition in the upper 6 bronchi, and quantitative deposition efficiency predictions across a range of particle sizes. (larger image)
The goal of this research is to evolve a complete simulation system for the human respiratory system, including detailed CFD analysis of the near-field external environment, gas-masks, inhalers, oral/nasal cavities and lung, including improved sub-grid deposition and pulmonary exchange modeling. This system will benefit: 1) medical
practitioners in the assessment of respiratory performance of unhealthy individuals before, during and after treatment, 2) pulmonary drug delivery and protection gear system designers, 3) regulatory and WMD response agencies that need to assess short- and longer-term exposure to various environmental contaminants and toxins.
Details of the particle deposition
work were published at BIOMED 2003 (paper [pdf]). More recent results that include the oxygen
uptake simulations will appear at the ASME Fluids Engineering Division Meeting in June 2004. Some animations of the unsteady simulations are available (anim. 1 and anim. 2).
For more info: email@example.com