Browsing by Subject "Particle transport"

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    Biomedical therapy delivery by fluid-mechanic means
    (2014-01) Weiler, James Michael
    The efficacy of many biomedical therapies can be improved when the physical processes which underlie the treatment modality are thoroughly understood. Many treatments make use of transport processes that are deeply embedded in mechanical engineering theory and practice. The research documented in this thesis is firmly based on fluid-mechanic, heat-transfer, mass-transfer, and particle transport theory. The thesis encompasses three categories of biomedical applications: drug distribution, thermal-based surgery, and drug delivery by means of particle transport.The first application dealt with a drug-eluting stent and with the distribution of the drug both into the artery wall by diffusion as well as into the blood flowing in the lumen via advection. This conjugate problem was redefined in dimensionless form and solved by numerical simulation to yield universal solutions. The solutions revealed the existence of a mass transfer boundary layer adjacent to the surface of the stent. Upstream diffusion, opposite to the direction of the advection, occurred. The results showed that the mass transfer into the flowing blood was orders of magnitude larger than the diffusive transfer into the artery walls. The focus of the second application was an in-depth, a fundamentals-based investigation of a new, minimally invasive treatment for menorrhagia. The involved physical processes include vapor transport into the uterine cavity, heat liberated by phase-change, and heat penetration into human tissue by means of conduction and blood perfusion. Cell necrosis was achieved by elevated temperatures sustained for a sufficient period of time. The outcome of this work was the depth of tissue necrosis corresponding to a given duration of the treatment. The predicted depths of necrosis compared favorably with clinical results. The final focus was the creation of a new methodology for the accurate delivery to targeted sites of drug particulates administered either through the mouth or the nose. The drug particles are carried through the respiratory system by an air stream. A numerical-based solution process was developed utilizing the laws of fluid mechanics, the physics of particle transport, and impaction theory. The final solution proved capable of predicting the landing locations of particles based on their respective sizes.
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    Interactions Between Fluid Flow, Heat Transfer, And Particle Transport In The Presence Of Jet-Axis Switching And Realistic Fluid Movers
    (2014-12) Gorman, John
    The overarching goal of this thesis is to identify and quantify new processes and phenomena related to fluid flow, heat transfer, and particle transport interacting in unique modes. The research can be categorized into three modes of interaction: (a) heat transfer processes governed by the complex patterns of fluid flow provided by real-world fluid-moving devices, (b) heat transfer processes which are governed by a naturally occurring, extraordinary fluid-flow phenomenon, and (c) interacting fluid flow, particle transport, and heat transfer all of which are governed by the aforementioned extraordinary fluid-flow phenomenon. These categories are respectively treated in individual chapters of the thesis. The traditional approach to convective heat transfer is virtually devoid of realistic fluid flow models. As a consequence, traditional convective heat transfer analysis is oversimplified to the point of being out of step with reality. This assertion is proven here, and a new fundamentals-based model of high fidelity involving realistic fluid movers of is created. Next, the extraordinary fluid flow phenomenon designated as jet-axis switching is introduced and illustrated quantitatively. This phenomenon occurs whenever a non-circular jet passes into and through an unrestricted space. When the jet is involved in a process called jet-impingement heat transfer, the zone of jet incidence is highly altered due to the axis-switching process. The ignoring of the switching process, which has been standard in all previous work on non-circular-jet impingement heat transfer, has been shown here to be highly error prone. The major part of the thesis encompasses jet-axis-switching fluid mechanics, convective heat transfer, and particle transport. An all-encompassing simulation model was created which took account of fluid-particle, particle-particle, fluid--impingement plate, and particle--impingement plate interactions, all with heat transfer. It was found that jet-axis switching exerted a major effect on the trajectories of the particles, with a corresponding impact on the particle collection efficiency of the impactor plate. The transfer of heat between the fluid and the impingement plate was little affected by any alterations in the pattern of fluid flow caused by the presence of particles. On the hand, direct particle-to-plate heat transfer is substantial.