ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

sinus might be of great importance to the causes of sinus diseases. However, how the
existence of AO affects sinus ventilation is not well understood. In this study, we
assessed the influence of AO on air ventilation through human maxillary sinus using
CFD simulation.
3. MATERIALS AND METHODS
CT scans of nasal cavities of two subjects were obtained for model reconstruction.
Subject I is with one AO on the right and two on the left. Subject II is with sole NO on
each maxillary sinus as a comparison.
The same process as reported in our previous study was carried out to reconstruct and
discretize the models from CT scans using Mimics (Version 12.1, Materialise n.v.) and
Hypermesh (Version 10.0, Altair Engineering Inc.) 4 . Fig. 1(A) shows the 3-Dimensional
model of nasal cavity of subject I. A hemisphere with radius of 40 mm was integrated
around the human face for prescription of zero gauge pressure on the surface. Fig. 1(B)
shows the top view of left (sinus I) and right (sinus II) sinuses of subject I. On the left
the first AO (AO1) is located very close to the NO. The second AO (AO2) is far from
the other two ostia. On the right the NO and the AO are located far from each other. Fig.
1(C) shows the left sinus of subject II (sinus III).
Fig. 1 3D reconstructed model. A, Lateral view of 3D model of subject I. Superiorinferior
views: B, sinuses of subject I. C, left sinus of subject II.
During the simulation, the air was assumed as incompressible and Newtonian. The nasal
wall was assumed as rigid wall. Zero gauge pressure was prescribed at the hemispheric
surfaces. This boundary condition stands for the realistic ambient pressure around the
human face. Simulations of transient airflow were carried out by applying sinusoidal
variation of flow rate corresponding to ventilation rate of 15 L/min at the pharynx (Fig.
2). Two cycles of respiration with duration of 4 seconds for each cycle were simulated.
The second cycle of respiration was evaluated. In addition, nasal blow was also
simulated for higher flow rate by applying 400 ml load within 0.5 second. Since the
current transient simulation would experience all the laminar regime, the transition
between laminar and turbulent regimes, and the full turbulent regime, low Reynolds
number (LRN) turbulent model of Wilcox 5 was chosen for the simulation. The LRN
turbulent model has been reported to be capable of reproducing the behavior of laminar,
transitional and fully turbulent flows 6 . Fluent (Version 6.3.26, Fluent, Inc.) was used to