Biomedical Engineering Reference
In-Depth Information
Fig. 1.2
Spherical particle
motion during inhalation in
the left chamber of the nasal
cavity
human subjects are difficult to undertake. For example, during normal respiration,
inhaled air often contains foreign particles such as dust, fumes and general pollutants
(Fig.
1.2
). In addition, drug delivery via the nose and mouth involves drug particles
suspended in the airflow. These flow behaviours of normal respiration and drug
delivery can be simulated using the CFPD approach, which is indeed much safer and
easier to perform than experimenting on a live human subject.
Nevertheless, the suggestion here is not that CFPD will replace experimental
testing but rather will serve as a viable alternative that complements experimental
methods. For example, the frontiers of CFPD research are still in a primitive state of
development, and newly developed models rely on experimental data as validation
for such topics as complex multiphase flows including drug powder aggregation or
deaggregation, chemical reactions, and particle breakup. With the recent increased
interest in this field, more capabilities and physics will be attainable. By using CFPD
models through CFD software packages, visualization of numerical solutions using
vectors, contours, or animated movies of unsteady flows can have a significant impact
on delivering solutions to respiratory research problems. Some of the aims of this
topic are to introduce to the reader the current research trends and to enable the reader
to understand and be able to make the right decisions when setting up the CFPD
models. In particular, new users often encounter incorrect numerically produced
flow characteristics that could have been wrongly interpreted as acceptable physical
phenomena. Numerical results obtained must always be thoroughly examined before
they are accepted. Therefore, the new user needs to learn how to properly analyse
and judge the computed results.
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