The physiological requirements of the nose are not only that it should warm, humidify and filter inspired air, but that it should also enable effective sensing by the olfactory receptors. The complex shape of the internal nose reflects the difficulty of accomplishing these different needs in a relatively compact anatomical compartment. From the perspective of modelling, the intricate geometry of the nose, combined with the ability of a person to vary the temporal profile of each inspiration, leads to interesting fluid mechanics. The seminar will describe some applications of computational modelling to nasal airflow, and outline some of the challenges in applying mathematical models to nasal physiology.