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Georgia Tech
1.
Harvey, Jeremy Paul.
Oscillatory compressible flow and heat transfer in porous media : application to cryocooler regenerators.
Degree: PhD, Mechanical Engineering, 2003, Georgia Tech
URL: http://hdl.handle.net/1853/5305 
► In this study the phenomenon of compressible flow and heat transfer in a porous media is modeled based on fundamental principles. The conservation equations for…
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▼ In this study the phenomenon of compressible flow and heat transfer in a porous media is modeled based on fundamental principles. The conservation equations for the two phases are transformed by the method of volume averaging which is an analytic method used to unite the microscale and macroscale effects characteristic to porous media flows. Unique to this analysis is that the model is valid for oscillatory, cryogenic flows such as that occurring in a regenerative cryogenic refrigerator such as a Pulse Tube Cryocooler (PTC.)
In a PTC the forced flow drive oscillations in the regenerator create Reynolds numbers high enough such that microscale inertial effects dominate the momentum equation. This phenomenon, known as the Forchheimer Effect, can be predicted and modeled based solely on fundamental principles and the method of volume averaging. The coefficients that characterize the Forchheimer momentum equation are determined experimentally.
In addition to pressure gradients, heat transfer within a porous media occurs due to temperature gradients. Conduction within the solid and fluid phases is made evident by volume averaging, but the determination of the conductivity coefficients requires numerical experiments and is unique to the geometry and conductivities of the two phases. Convection between the two phases is the dominant mode of heat transfer within the porous media. Determination of the convective heat transfer coefficient for a porous media requires physical experiments.
Heat transfer and pressure gradients in the porous media are always competing effects leading to a model which requires coupling of the momentum and energy equations. These competing effects are united with the concept of entropy generation which relies on the second law of thermodynamics. All real processes generate entropy, and the most efficient processes which balance pressure gradients and heat transfer generate minimum entropy. This concept of minimum entropy generation is unique. As a result, minimum entropy generation should always be used as the criteria for thermodynamic optimization of thermohydraulic systems.
Advisors/Committee Members: Desai, Prateen V. (Committee Chair), Ghiaasiaan, S. Mostafa (Committee Member), Kirkconnell, Carl S. (Committee Member), Morris, Jeffrey F. (Committee Member), Yoda, Minami (Committee Member).
Subjects/Keywords: Method of lines dispersion
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APA (6th Edition):
Harvey, J. P. (2003). Oscillatory compressible flow and heat transfer in porous media : application to cryocooler regenerators. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/5305
Chicago Manual of Style (16th Edition):
Harvey, Jeremy Paul. “Oscillatory compressible flow and heat transfer in porous media : application to cryocooler regenerators.” 2003. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021.
http://hdl.handle.net/1853/5305.
MLA Handbook (7th Edition):
Harvey, Jeremy Paul. “Oscillatory compressible flow and heat transfer in porous media : application to cryocooler regenerators.” 2003. Web. 17 Apr 2021.
Vancouver:
Harvey JP. Oscillatory compressible flow and heat transfer in porous media : application to cryocooler regenerators. [Internet] [Doctoral dissertation]. Georgia Tech; 2003. [cited 2021 Apr 17].
Available from: http://hdl.handle.net/1853/5305.
Council of Science Editors:
Harvey JP. Oscillatory compressible flow and heat transfer in porous media : application to cryocooler regenerators. [Doctoral Dissertation]. Georgia Tech; 2003. Available from: http://hdl.handle.net/1853/5305
Georgia Tech
2.
Miller, Ryan Michael.
Continuum Modeling of Liquid-Solid Suspensions for Nonviscometric Flows.
Degree: PhD, Chemical Engineering, 2004, Georgia Tech
URL: http://hdl.handle.net/1853/4864
► A suspension flow model based on the "suspension balance" approach has been developed. This work modifies the model to allow the solution of suspension flows…
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▼ A suspension flow model based on the "suspension balance" approach has been developed. This work modifies the model to allow the solution of suspension flows under general flow conditions. This requires the development of a frame-invariant constitutive model for the particle stress which can take into account the spatially-varying local kinematic conditions. The mass and momentum balances for the bulk suspension
and particle phase are solved numerically using a finite volume method. The particle stress is based upon the computed rate of strain and the local kinematic conditions. A nonlocal stress
contribution corrects the continuum approximation of the particle phase for finite particle size effects. Local kinematic conditions are accounted through the local ratio of rotation to extension in the flow field. The coordinates for the stress definition are the local principal axes of the rate of strain field.
The developed model is applied to a range of problems. (i) Axially-developing conduit flows are computed using both the full two-dimensional solution and the more computationally
efficient "marching" method. The model predictions are compared to experimental results for cross-stream particle concentration profiles and axial development lengths. (ii) Model
predictions are compared to experiments for wide-gap circular Couette flow of a concentrated suspension in a shear-thinning liquid. With minor modification, the suspension flow model predicts the major trends and results observed in this flow. (iii) Comparisons are made to experiments for an axisymmetric contraction-expansion. Model predictions for a two-dimensional planar contraction flow test the influence of model formulation. The variation of the magnitude of an isotropic particle normal stress with local kinematic conditions and anisotropy in the
in-plane normal stresses are both explored. The formulation of the particle phase stress is found to have significant effects on the solid fraction and velocity. (iv) Finally, for a rectangular
piston-driven flow and an obstructed channel flow, a "computational suspension dynamics" study explores the effect of particle migration on the bulk flow field, system pressure drop
and particle phase composition.
Advisors/Committee Members: Forney, Larry (Committee Co-Chair), Morris, Jeffrey F. (Committee Co-Chair), Carr, Wallace W. (Committee Member), Koros, William J. (Committee Member), Wick, Timothy M. (Committee Member), Yiacoumi, Sotira Z. (Committee Member), Yoda, Minami (Committee Member).
Subjects/Keywords: Two-phase flow; Suspension flow; Frame-invariant rheology; Finite volume method; Shear-induced migration; Suspension balance model; Shear flow; Finite volume method; Two-phase flow; Rheology; Continuum mechanics
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APA ·
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APA (6th Edition):
Miller, R. M. (2004). Continuum Modeling of Liquid-Solid Suspensions for Nonviscometric Flows. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/4864
Chicago Manual of Style (16th Edition):
Miller, Ryan Michael. “Continuum Modeling of Liquid-Solid Suspensions for Nonviscometric Flows.” 2004. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021.
http://hdl.handle.net/1853/4864.
MLA Handbook (7th Edition):
Miller, Ryan Michael. “Continuum Modeling of Liquid-Solid Suspensions for Nonviscometric Flows.” 2004. Web. 17 Apr 2021.
Vancouver:
Miller RM. Continuum Modeling of Liquid-Solid Suspensions for Nonviscometric Flows. [Internet] [Doctoral dissertation]. Georgia Tech; 2004. [cited 2021 Apr 17].
Available from: http://hdl.handle.net/1853/4864.
Council of Science Editors:
Miller RM. Continuum Modeling of Liquid-Solid Suspensions for Nonviscometric Flows. [Doctoral Dissertation]. Georgia Tech; 2004. Available from: http://hdl.handle.net/1853/4864
Georgia Tech
3.
Furbank, Roy Jeffrey.
Drop formation from particulate suspensions.
Degree: PhD, Chemical Engineering, 2004, Georgia Tech
URL: http://hdl.handle.net/1853/4992
► This research presents an experimental study of the formation of drops of suspensions consisting of a viscous liquid and spherical, neutrally buoyant, noncolloidal particles. Pendant…
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▼ This research presents an experimental study of the formation of drops of suspensions consisting of a viscous liquid and spherical, neutrally buoyant, noncolloidal particles. Pendant drop formation and low Reynolds number jetting of suspensions are investigated, as is the transition between the two. Throughout, the particles utilized are on the order of 100 μm and the orifice from which the drops are formed is on the order of 1 mm.
The presence of the particulate phase causes the structure at pinch-off in the pendant drop regime to change noticeably from that of pure liquids. Thick cone-like structures, termed "spindles" here, form at either end of the slender thread and are the result of particle motions during necking. These spindles become more pronounced with increasing particle concentration.
Depending on particle concentration, the particles can have either a destabilizing effect (low concentration) on drop formation or a stabilizing one (high concentration). At low concentrations, the particles lead to earlier rupture of the thread and much shorter jet lengths, while at elevated concentrations the particles stabilize the thread after rupture and lead to fewer satellite drops as well as induce jetting at lower flower rates.
A two-stage model has been proposed to describe the necking process for particle-laden suspensions in the pendant drop regime. The first stage occurs when the thread is thick relative to the particles and the effect of the particles can be attributed solely to a change in the effective viscosity of the mixture. The second stage occurs nearer pinch-off when the thread has thinned to only a few particle diameters. In this stage the individual particle motions within the thread determine the behavior and the thread ultimately ruptures over a region of the thread devoid of particles.
Advisors/Committee Members: Schork, F. Joseph (Committee Chair), Morris, Jeffrey F. (Committee Co-Chair), Breedveld, Victor (Committee Member), Forney, Larry J. (Committee Member), Mucha, Peter J. (Committee Member), Smith, Marc K. (Committee Member).
Subjects/Keywords: Drop formation; Pendant drops; Jetting; Free-surface flows; Suspensions
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APA ·
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APA (6th Edition):
Furbank, R. J. (2004). Drop formation from particulate suspensions. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/4992
Chicago Manual of Style (16th Edition):
Furbank, Roy Jeffrey. “Drop formation from particulate suspensions.” 2004. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021.
http://hdl.handle.net/1853/4992.
MLA Handbook (7th Edition):
Furbank, Roy Jeffrey. “Drop formation from particulate suspensions.” 2004. Web. 17 Apr 2021.
Vancouver:
Furbank RJ. Drop formation from particulate suspensions. [Internet] [Doctoral dissertation]. Georgia Tech; 2004. [cited 2021 Apr 17].
Available from: http://hdl.handle.net/1853/4992.
Council of Science Editors:
Furbank RJ. Drop formation from particulate suspensions. [Doctoral Dissertation]. Georgia Tech; 2004. Available from: http://hdl.handle.net/1853/4992
Georgia Tech
4.
Diao, Jie.
Development of Techniques to Quantify Chemical and Mechanical Modifications of Polymer Surfaces: Application to Chemical Mechanical Polishing.
Degree: PhD, Chemical Engineering, 2004, Georgia Tech
URL: http://hdl.handle.net/1853/7628
► This thesis is devoted to development of techniques to quantify chemical and mechanical influences during chemical mechanical polishing (CMP) near the surface of a polymer…
(more)
▼ This thesis is devoted to development of techniques to quantify chemical and mechanical influences during chemical mechanical polishing (CMP) near the surface of a polymer film, poly (biphenyl dianhydride-p-phenylenediamine) (BPDA-PDA). To quantify chemical modifications during CMP, an iterative algorithm has been proposed to extract depth profiles based on Ficks second law of diffusion in a multi-element system from data supplied by angle resolved x-ray photoelectron spectroscopy. It has been demonstrated that the technique can be used to quantify the depth of chemical modification of BPDA-PDA surfaces treated with alkaline solutions. Polymer chains near the surface realign themselves during CMP and polarized infrared spectroscopy is chosen in this thesis to
quantify chain orientations induced by CMP to evaluate the mechanical influence. A theoretical framework based on a 44 matrix method for spectral simulation together with an oscillator model for BPDA-PDA has been used to obtain quantitative chain orientation information on a post-CMP BPDA-PDA sample by fitting simulated polarized infrared spectra to experimentally generated spectra. Verification of the oscillator model was established from the complex refractive indices of BPDA-PDA films, which were determined using a new method (R/T ratio method) developed in this thesis to extract complex refractive indices of films with biaxial symmetry from polarized transmission and reflection spectra.
Advisors/Committee Members: Hess, Dennis W. (Committee Chair), Morris, Jeffrey F. (Committee Co-Chair), Bottomley, Lawrence A. (Committee Member), Danyluk, Steven (Committee Member), Henderson, Clifford L. (Committee Member), Samuels, Robert J. (Committee Member).
Subjects/Keywords: Chemical mechanical polishing; Depth profile; Polymers; Optical properties; Angle resolved XPS
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Record Details
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APA ·
Chicago ·
MLA ·
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CSE |
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to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Diao, J. (2004). Development of Techniques to Quantify Chemical and Mechanical Modifications of Polymer Surfaces: Application to Chemical Mechanical Polishing. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/7628
Chicago Manual of Style (16th Edition):
Diao, Jie. “Development of Techniques to Quantify Chemical and Mechanical Modifications of Polymer Surfaces: Application to Chemical Mechanical Polishing.” 2004. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021.
http://hdl.handle.net/1853/7628.
MLA Handbook (7th Edition):
Diao, Jie. “Development of Techniques to Quantify Chemical and Mechanical Modifications of Polymer Surfaces: Application to Chemical Mechanical Polishing.” 2004. Web. 17 Apr 2021.
Vancouver:
Diao J. Development of Techniques to Quantify Chemical and Mechanical Modifications of Polymer Surfaces: Application to Chemical Mechanical Polishing. [Internet] [Doctoral dissertation]. Georgia Tech; 2004. [cited 2021 Apr 17].
Available from: http://hdl.handle.net/1853/7628.
Council of Science Editors:
Diao J. Development of Techniques to Quantify Chemical and Mechanical Modifications of Polymer Surfaces: Application to Chemical Mechanical Polishing. [Doctoral Dissertation]. Georgia Tech; 2004. Available from: http://hdl.handle.net/1853/7628
. 
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