Regional Deposition of Particles in an Image-Based Airway Model: Large-Eddy Simulation and Left-Right Lung Ventilation Asymmetry

Figures & data

FIG. 1 Realistic airway tree geometry acquired using a Siemens Sensation 64 multi-detector row computed tomography (MDCT) scanner housed at the Iowa Comprehensive Lung Imaging Center at the University of Iowa.

FIG. 2 A CT-based airway geometrical model with branch labels.

FIG. 3 Contours of (a) mean velocity (m/s) and (b) mean TKE (m²/s²) of the flow.

FIG. 4 Deposition locations for 2.5, 10, and 30-μm particles (left, middle, right).

FIG. 5 Oral airway deposition patterns for 2.5, 10, and 30-μm particles with respective deposition efficiencies of 3.9%, 9.5%, and 75.0% (left, middle, right).

FIG. 6 Overall deposition efficiency vs. (a) particle size and (b) particle Stokes number for original and refined meshes.

FIG. 7 Oral deposition efficiency vs. (a) particle size and (b) particle Stokes number for original and refined meshes.

FIG. 8 Comparison of oral deposition results to Grigic et al. (2004).

FIG. 9 Deposition efficiency for the first generation.

FIG. 10 Deposition efficiency in the second generation. Different symbols in the current LES denote different bifurcations.

FIG. 11 Deposition efficiency in the third generation. Different symbols in the current LES denote different bifurcations.

FIG. 12 Deposition efficiency in the fourth generation. Different symbols in the current LES denote different bifurcations.

FIG. 13 Lobar (a) deposition and (b) ventilation of 2.5, 5, 10, 20, and 30-μm particles.

TABLE 1 Lobar deposition for 2.5 and 5.0-μm particles compared against 4.0-μm particles from Subramaniam et al. (2003)

Lung lobe	2.5 μm	5.0 μm	4.0 μm*
LUL	0.15	0.14	0.08
LLL	0.34	0.38	0.16
RUL	0.15	0.14	0.08
RML	0.03	0.03	0.04
RLL	0.33	0.31	0.16
*Results from Subramaniam et al. (2003) are for tracheobronchial region only, which is why their fractions do not sum to unity, as some particles in their model deposit in the alveolar region. However, their particle deposition is similar qualitatively to the current study, with the lower lobes receiving the greatest fraction of particles.

TABLE 2 Deposition ratio between upper (U) to lower lobes (L) U/L, for the right and left lungs (note that the RML is not included in the calculation; +/– denotes standard deviation)

Size (μm)	U/L right	+/−	U/L left	+/−
30	0.20	0.27	0.54	0.18
20	0.41	0.27	0.52	0.32
10	0.40	0.09	0.31	0.04
5	0.46	0.09	0.39	0.04
2.5	0.47	0.13	0.44	0.07

FIG. 14 Left vs. right lung (a) deposition and (b) ventilation of 2.5, 5, 10, 20, 30-μm particles.

FIG. 15 L/R ratio vs. Stokes number at the trachea and glottis.

TABLE 3 Left lung (L) over right lung (R) ratio for 2.5, 5, 10, 20, and 30-μm particles, +/– denotes standard deviation

Size (um)	L/R deposited	+/−	L/R ventilated	+/−
30	1.60	0.47	1.56	0.47
20	1.41	0.40	1.37	0.38
10	1.35	0.27	1.17	0.28
5	1.21	0.25	1.15	0.17
2.5	1.01	0.19	1.16	0.16

FIG. 16 Particle transport profiles at normalized time t* = 0.13. (a) 2.5-μm particles with Stk_glottis= 0.006, (b) 20-μm particles with Stk_glottis= 0.405. The unit of air speed is m/s.

FIG. 17 Iso-surfaces of air speed of 1.58 m/s and particle transport profile for 2.5-μm particles at (a) t* = 0.11, (b) t* = 0.13.

Grigic , B. , Finlay , W. H. , Burnell , P. K. P. and Heenan , A. F. 2004 . In Vitro Intersubject and Intrasubject Deposition Measurements in Realistic Mouth-Throat Geometries . J. Aerosol Sci. , 35 : 1025 – 1040 .

 Web of Science ®Google Scholar

Subramaniam , R. P. , Asgharian , B. , Freijer , J. I. , Miller , F. J. and Anjilvel , S. 2003 . Analysis of Lobar Differences in Particle Deposition in the Human Lung . Inhal. Technol. , 15 : 1 – 21 .

 PubMed Web of Science ®Google Scholar