Numerical modeling of nasal airflow

Abstract

Problem: The objective of the research was to develop accurate numerical models of nasal airflow using computational fluid dynamics (CFD), a computer-based flow modeling technology widely used in engineering, to improve understanding of nasal airflow with a view to developing a method to assist in planning of nasal surgery. Methods: Computer-aided design (CAD) models of the nasal cavity were generated from nasal CT scans of healthy volunteers using specialized computer software (Mimics, Materialise, Belgium). These anatomically accurate CAD models were used as the basis for 3-dimensional computer grids (meshes) of the nasal cavity. Numerical simulations of nasal airflow were performed on the meshed models using commercial CFD software (Fluent 6, Fluent Inc, Lebanon, NH). Numerical flow predictions were validated using experimental data obtained from an exact solid model of one of the healthy nasal passages. Results: Numerical simulations of nasal airflow showed good agreement with experimental results and with the results of previous experimental studies published in the literature. Potentially important inter-individual variations have been noted, which may account for the outcome variability of some forms of surgical intervention (eg, inferior turbinate surgery). Analysis of wall shear stress (friction) within the nasal cavity has revealed high levels in Little’s area, suggesting a possible connection to the predilection of anterior epistaxis for this site. Conclusion: Numerical simulation of nasal airflow using computational fluid dynamics techniques offers a novel, noninvasive method of assessing of nasal airflow and related phenomena. Alteration of the computer model can be performed to simulate pre-operatively the results of nasal surgery (Virtual Surgery), which may be of considerable clinical benefit. Significance: Numerical modeling of nasal airflow provides objective, patient-specific information regarding nasal airflow characteristics that is not currently available by other methods. It also potentially offers a unique method of preoperatively planning surgery for nasal obstruction. Support: United Hospital’s Trust Research Fellowship.