Scientists find that the human nose is more complicated than a jumbo jet
6 January 2005
Winter colds can give you a blocked up nose that stops you smelling chimney smoke, roasting chestnuts, warming winter puddings and the other seasonal scents. Now researchers funded by the Biotechnology and Biological Sciences Research Council (BBSRC) have not only discovered how air moves through the nose bringing you those smells but their work may lead to new ways of unblocking it and helping you to breathe more easily. They have even found that the airflow through the human nose is more complicated than that over a jumbo jet’s wing.
The scientists at Imperial College London have combined biological mechanics and aeronautical engineering to construct transparent 3D models of the nose. By running water or a special refractive-index-matched fluid through the models they have been able to map the flow pattern through the nasal cavity to work out where air goes when you breathe in. Tiny coloured beads circulate through the model nose to simulate airflow and this is captured on fast digital cameras. Professor Bob Schroter who jointly leads the research said, “From quiet breathing to rapid sniffing, we want to know exactly what is happening.”
The fluid dynamics of the nose is one of the most complex in the body, even more so than the flow of blood through the heart, with anatomical structures that cause eddies, whirls and recirculation.
Dr Denis Doorly, the other principal researcher, said, “People are used to the flows around an aeroplane being complicated but that is in some ways simpler than understanding the flows inside the nose. The geometry of the nose is highly complex, with no straight lines or simple curves like an aircraft wing and the regime of airflow is not simply laminar or turbulent.”
The research has mapped the flow of air around anatomical landmarks in the nose, such as the conchae and has discovered why we need to breathe deeply to smell a flower. Our sense of smell relies on a sample of air reaching the olfactory bulb at the top of the nose and that requires a sharp breathe and a high velocity shot of air to reach it. The Imperial scientists have found that the geometry of the nose causes the air to eddy around in the vicinity of the bulb so you can smell the flower.The research is a significant step forward from what had been learned about the nose from studying cadavers and animals, and may soon be helping surgeons plan their operations and drug companies to develop new ways of delivering drugs through the nose straight into the bloodstream – as well as new products to unblock the nose.
Notes to editors
This research features in the January 2005 issue of Business, the quarterly magazine of the Biotechnology and Biological Sciences Research Council.
The scientists constructed their model nose from existing CT scan datasets of anonymous patients found to be nasally healthy. They compiled the CT ‘slices’ together to create the instructions for a 3D printer to create a model out of soft plaster material using a technique known as rapid prototyping.
This was used to cast the model, which is made from transparent silicone. The model is twice life-size.
Water is used to recreate airflow as it can be slowed down by a factor of ten without losing realistic movement detail.
The experiment is partnered by a computational fluid dynamics model handled by the computers of the London e-Science centre, also at Imperial College London.
The Biotechnology and Biological Sciences Research Council (BBSRC) is the UK funding agency for research in the life sciences. Sponsored by Government, BBSRC annually invests around £380 million in a wide range of research that makes a significant contribution to the quality of life for UK citizens and supports a number of important industrial stakeholders including the agriculture, food, chemical, healthcare and pharmaceutical sectors. http://www.bbsrc.ac.uk
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