Modeling Respiratory Airflows
Except for the skin, the respiratory tract interacts with the environment more than any other body system. To study some aspects of this interaction, researchers in the pulmonary fluid mechanics lab in the Department of Bioengineering have constructed physical and numerical models of human and animal nasal cavities. By using the laws of fluid mechanical similarity, flows in the large scale physical models are created which are exact duplicates of those which occur in the real systems.
The twenty times enlarged human model--the world's largest operational nose--has been used to study the fluid dynamical aspects of the sense of smell in research done jointly with workers in the Department of Physiology at SUNY, Syracuse. Exactly how the human or animal nose and brain work together to distinguish between the great variety of different inhaled odorants is still not understood. One theory is that the physical properties of the gaseous odorants such as mucus solubility and diffusivity create a pattern of absorption across the olfactory surface epithelium located on the posterior roof of the nasal cavity and that this imposed absorption pattern interacts with the inherent anatomical pattern of olfactory receptor distribution to produce unique electrical signals which are recognized by the brain.
The figure shows an odorant absorption pattern for the entire human nasal cavity computed from a numerical, finite element human nasal model for inhalation of a highly mucus-soluble odorant. The flow is from left to right and the velocity field predicted by the numerical model was validated by comparison with measurements in the physical model. The olfactory region is in the upper right corner of the figure. The amount of odorant absorbed ranges from red for large amounts to blue for small amounts. Similar nasal mucosal uptake patterns occur for highly soluble inhaled pollutant gases such as formaldehyde. Combinations of physical and numerical models can be used to study a wide range of respiratory and circulatory flows of medical interest.