Numerical Simulation of Airflow, Particle Deposition and Drug Delivery in a Representative Human Nasal Airway Model

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Title: Numerical Simulation of Airflow, Particle Deposition and Drug Delivery in a Representative Human Nasal Airway Model
Author: Shi, Huawei
Advisors: Tarek Echekki, Committee Member
Chong Kim, Committee Member
Kevin Lyons, Committee Member
Clement Kleinstreuer, Committee Chair
Zhe Zhang, Committee Co-Chair
Abstract: 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&#60;=Q<=20L&#8260;min and 1nm<=dp&#60;=50um . 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 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.
Date: 2007-08-07
Degree: PhD
Discipline: Mechanical Engineering

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