The human nasal cavities, each with an effective length of only 10cm, feature a wide array of basic flow phenomena due to their complex geometries. Dependent on such airflow fields are the transport and deposition of micro- and nano-particles in the human nasal cavities, of interest to engineers, scientists, air-pollution regulators, and healthcare officials.; By utilizing advanced CAD and reverse engineering skills, a realistic model of the human nasal cavity was constructed from MRI image data for 3-D computer simulations. Assuming laminar quasi-steady airflow, dilute micro- and nano-particle suspension flows and local deposition efficiencies were analyzed for 7.5≤Q≤20L/min and 1nm ≤ d p ≤ 50mum. Simulation results are in good agreement with experimental measurements, assuring that computational fluid-particle dynamics (CFPD) is an effective and efficient tool to predict both toxic and therapeutic aerosol dynamics in the nasal cavities.; Both nano- and micro-particle deposition efficiencies are influenced by particle size and airflow rate. Specifically, deposition of nanoparticles (1nm ≤ dp ≤ 150nm) is governed by particle diffusion or Brownian motion, and decreases with increasing particle size and airflow rate in the nasal cavity. For microparticle deposition, the major mechanism is particle inertia. As a result, microparticle deposition increases for larger particles and higher airflow rates.; Computational efforts were extended to nasal drug delivery, i.e., a droplet-spray model was developed which can be used to simulate nasal sprays. However, it turned out, after varying several droplet-spray parameters and trying different inlet conditions, that direct nasal sprays cannot achieve efficient drug delivery to the desirable surface area, e.g., the human olfactory region. However, a new nasal drug delivery method, called bi-directional nasal drug delivery, was successfully tested. The simulation results indicate that bi-directional nasal drug delivery overcomes major shortcomings of nasal sprays and may be a good candidate for the next generation of nasal drug delivery systems.
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