Computational Modelling of Flow in the Human Nasal Airway

John Watterson, Neil Bailie, Orla Grant, Brendan Hanna, Jonathan Cole

Research output: Contribution to conferenceAbstract

Abstract

The anatomical and physiological complexity of the human nasal passage is a significant obstacle to the provision of effective surgical treatment of disorders of the nasal airway. There is no universally accepted method for objectively characterising nasal airflow. Consequently, the pre-operative assessment of Ear, Nose and Throat (ENT) surgeons is subjective, based on a visual inspection of the nasal passage or computed tomography (CT) scans of the airway. Often the cause of the disorder is apparent and treatment straightforward; but there are hard cases in which it is difficult to be sure of the best course of action, and for which the benefits of surgical intervention cannot be predicted satisfactorily.

An objective nasal assessment tool is being developed to address this issue. The value of the tool is based on the hypothesis that airflow patterns in a nasal passage are a good means of assessing respiratory problems. The tool is computational in nature and employs CT scans and computational fluid dynamics (CFD). Sets of two-dimensional CT scans are converted into three-dimensional computer aided design (CAD) geometries. The volume enclosed within the CAD geometries is sub-divided into finite volumes (tetrahedra). CFD modelling of airflow through the nasal passage then makes use of the mesh of finite volumes and is capable of elucidating flow patterns, velocities and stresses.

The method has been validated using in vitro experiments, including, flow visualisation, pressure drop measurements and particle image velocimetry (PIV) on a full scale model of one half the nasal passage of a healthy human adult. The method has been optimised through mesh-dependence studies and an investigation of the influence of turbulence modelling.

The validated method has been applied to the study of the influence of classical nasal abnormalities, including hypertrophied turbinates, septal deviation and septal spurs. It has been found that the location of nasal obstruction is more important than the nature of the obstruction or its magnitude; in particular, obstructions of the middle nasal passage are most critical. Regions of high wall shear stress have also been identified in the work. Since these correspond to regions with a high predilection for epistaxis (bleeding), a link is hypothesised between wall shear stress and nose bleeds.
Original languageEnglish
Publication statusPublished - 07 Apr 2006
EventNorthern Ireland Biomedical Engineering Society Spring Meeting - University of Ulster, Jordanstown, Jordanstown, Northern Ireland, United Kingdom
Duration: 07 Apr 200607 Apr 2006

Conference

ConferenceNorthern Ireland Biomedical Engineering Society Spring Meeting
CountryUnited Kingdom
CityJordanstown, Northern Ireland
Period07/04/200607/04/2006

Keywords

  • human nasal airflow
  • CFD
  • CT scans

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