A Computational Study of Airflow in a Standardized Human Nasal Cavity: Implications Regarding Olfaction

Open Access
Author:
Shenk, Elizabeth Marie
Area of Honors:
Bioengineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Brent Craven, Thesis Supervisor
  • Brent A Craven, Thesis Supervisor
  • William O Hancock, Thesis Supervisor
  • Peter J Butler, Faculty Reader
Keywords:
  • human olfaction
  • nasal airflow
  • standardized human nasal cavity
  • CFD analysis
Abstract:
Healthy humans breathe through their nose even though its complex geometry imposes a significantly higher resistance in comparison with mouth breathing. The nose serves many functions, the focus of which in this thesis is olfaction. Sniffing is typically considered to enhance the sense of smell; the flow rate through the human nasal cavity during sniffing is significantly higher than that which is experienced during restful breathing. This study uses a standardized three-dimensional model of the human nasal cavity and computational fluid dynamics to study the physiology and fluid dynamics of human respiration and olfaction during sniffing. The flow is modeled as quasi-steady and laminar due to Womersley and Reynolds number calculations. The qualitative features of the CFD solutions are fairly consistent for the coarse, medium, and fine grids. The overall flow patterns are remarkably similar regardless of the refinement of the grid; however there are marked differences in the flow rates and velocity profiles as the grid refinement progresses from coarse to medium to fine. The olfactory region of the human nasal cavity experiences a relatively low velocity of airflow, as well as a relatively low fraction of the airflow through the nasal cavity in this simulation. The high flow rate (40 L/min) simulated as the human sniffing flow rate did not appear to facilitate transport of odorant molecules into the olfactory region. Overall, the results from this study do not appear to show any significant benefits to human olfactory ability during sniffing.