Case Studies in the Human Respiratory System - Computational Fluid and Particle Dynamics in the Human Respiratory System - page 229

Chapter 8
Case Studies in the Human Respiratory System

8.1 Introduction

The use of CFD in biomedical applications has emerged as a legitimate alternative
to traditional cast models and human experimental methods. With recent devel-
opments in computational hardware, biomedical imaging instruments and CFD
techniques, new and exciting research possibilities for the human respiratory system
have emerged—some of which were discussed in Chap. 1. In the preceding chap-
ters important fundamental steps were described in relation to the development of
computational models of the respiratory system. The morphology and physiological
nature of the respiratory system outlined in Chap. 2 highlights the increased level
of complexity that is involved in biomedical CFD applications. For example, small
scales, surface irregularities, and high curvatures are all characteristic of the nasal
cavity, larynx and upper lung airway. These issues bring to fore the need for con-
vergence of multi-disciplines, involving biomedical imaging, reverse engineering
in Computer-Aided-Design (CAD), and finally CFD. In Chap. 3 the needed steps
for reconstructing the respiratory passage were discussed. In fact, these preparatory
steps can be viewed as a prerequisite for construction of any complex geometry.
From the reconstructed CAD model, CFD simulations can then be undertaken by
first developing a computational mesh (Chap. 4), and then applying the appropriate
physics to suit the problem at hand. For example, fluid flow problems, such as in-
halation and humidification of the inhaled air, need to consider the fundamentals of
fluid dynamics as described in Chap. 5, whereas the inclusion of inhaled particles
for drug delivery or for harmful particles suspended in the atmosphere require addi-
tional particle equations and models which were discussed in Chap. 6. The correctly
defined problem is then ready to be solved computationally. The numerical schemes
and algorithms found in Chap. 7 are the cornerstone of any CFD analysis. Funda-
mental understanding of the conservation equations and numerical approximations
is prerequisite for generating efficient solutions.
Having laid the groundwork to establish a strong theoretical base, this chapter cul-
minates in the foundational knowledge attained by applying the theories and putting
them into practice through selected demonstrative applications. From a practical
viewpoint, the selected detailed case studies in this chapter will provide the reader