Nasal geometry and airflow dynamic in Chinese

Abstract

Nasal cavity is acomplicated and highly folded structure. The special configuration of the nasal cavity enhances the nasal functions in filtering and conditioning the air inhaled as well as carrying out the sense of smelling. The geometry of each nasal cavity is unique. Nevertheless,the dimensional changes of the nasal cavities can be predicted from the background and health conditions ofthe subjects. This project aims to (i) study the relationship and effect of the defined variables on the "volume", "surfacearea", "depth","width" and "length" of the Chinese nasal cavities; (ii) investigate how the nasal airflow velocity can be predicted by the dimensional changes of the nasal pathway caused by these defined variables; and(iii) determine the external nasal features of Hong Kong Chinese. From 2005 to 2008,146 subjects were recruited in this study. Both spiral and cone beam CT scans were utilised to produce the simulation models of nasal cavity. As no related study has ever utilised the cone beam CT scans,reliability tests were performed to verify the out comes and the results have proved to be satisfactory. A questionnaire was designed to collect the health information of the participants. The sizeof their nasal cavities was then correlated with the data by statistical approaches, including Pearson product-moment correlation coefficient andSpearman‘s rank correlation coefficient, so as to study the effect of the health conditions on the size of noses. The same group of nasal models were further employed in the Computational Fluid Dynamic (CFD) simulation for determining the air flow velocity profile inside the nasal cavity. The simulation results were applied to illustrate how the changes of the nasal dimension triggered by the defined variables and the way that they would influence the airflow pattern and velocity profile inside the nasal cavity. The age, weight, height and gender ofthe participants,as well as their habits of exercise and alcohol consumption were found to be significant in contributing to the variation of nasal geometry. The habits and health conditions of the participants had also been proven to affect the nasal airflow velocity profile. Female participants were found to have an overall higher velocity profile than the male participants. The age, weight and height of the participants were able to explain the differences in the velocity profile curves generated within the same gender. Lastly,women seem to have a larger nasofrontal and nasal tip angle as well as a smaller nasolabial angle than men. The size of the nasofrontal angles is found to afgect the airflow velocity profile generated inside the anteriorsection of the nasal cavity.

Date of Award	15 Jul 2009
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Yee Tak Andrew LEUNG (Supervisor)