Case Studies in the Human Respiratory System - Computational Fluid and Particle Dynamics in the Human Respiratory System - page 290

by observing the particle trajectories (Fig. 8.48 ). It is known that larger particles
that possess high inertia (i.e. Stokes number characteristics) need to be aligned with
the flow streamlines to avoid impaction. This implies that the particles need to be
projected at a clear unobstructed path in the nasal airway rather than be projected at
walls.

Fig. 8.48 Particle trajectories for 10 and 20 μ m particles at different swirl fractions

0, the velocity magnitude is entirely composed of axial velocity, which
projects the particles vertically. High inertia particles are directed at the roof of the
nasal vestibule and do not have enough time to slow down and adapt to the gas phase
streamlines. However smaller inertia particles can adapt to the flow streamlines more
readily. One idea to overcome this is to insert the nasal spray at an angle (insertion
angle) that would provide such alignments with the flow streamlines (Inthavong et al.

When λ →