Case Studies in the Human Respiratory System - Computational Fluid and Particle Dynamics in the Human Respiratory System - page 293

Fig. 8.50 Deposition patterns for a 10 μ m b 15 μ m and c 50 μ m particles released uniformly from

the inlet surface normal to the nostril openings at u ∗ = 1 and u ∗ =

10

the particle to adjust to the airflow conditions. For a fixed distance (nostril opening
to the top of the vestibule), an increase in u ∗ will decrease the time taken to cover
this distance. This leads to a shorter time and distance for the particle to adapt to
the gas phase conditions and presents a higher impactability than that calculated by
the Stokes number alone. The influence of the injected particle velocity is still felt
as the airflow begins to curve. As particle size increases, so does the relaxation time
that the particle needs to adapt to flow changes. As a result, significant deposition
increases occur at lower u ∗ values for larger Stokes numbers.
Figure 8.50 displays the deposition sites for the two extreme cases, d p = 10 μ m

m, subjected to u ∗ and d p = 50 μ m, and for a mid-range particle, d p = 15 μ = 1