Something may be as plain as the nose on your face, but what goes on inside that nose is neither obvious nor simple. The anatomical structure of the nose causes complex patterns as indrawn air swirls, eddies and recirculates around and over the curved surfaces.Scientists Robert C. Schroter and Denis Doorly at Imperial College London have combined biomechanics with aeronautical engineering to sniff out what really happens inside this mysterious sensory organ. They have used CT scans to build a three-dimensional tranparent nose through which they can pump fluid containing tiny colored beads. Computed streamlines show flow patterns of dye filaments injected through a model nose.As the fluid moves, simulating different types of breath, digital cameras track the beads’ progress through the nasal cavity, and computers chart the fluid dynamics. Schroter and Doorly have discovered that a deep sniff with quick intake, for example, makes the air circulate rapidly around the olfactory bulb at the top of the nose. Tiny increases in flow speed can direct the airstream to different parts of the nasal passages. The researchers believe that inhalation mapping could help ear, nose and throat specialists refine their surgeries and could lead to better means of delivering drugs into the bloodstream. A facial model simulates the internal passageways in the nose. Images courtesy of Imperial College London.