Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 6 of 6
Full-Text Articles in Mechanical Engineering
Solidification Experiments And Magnetohydrodynamic Models In Electromagnetic Levitation, Gwendolyn Bracker
Solidification Experiments And Magnetohydrodynamic Models In Electromagnetic Levitation, Gwendolyn Bracker
Doctoral Dissertations
Electromagnetic levitation (EML) is a technique for containerless processing. The unique environment of containerless processing allows for the study of highly reactive melts at elevated temperatures. In containerless processing, the interface between a melt and its container is removed, reducing chemical contamination. In addition, levitation techniques reduce the available heterogeneous nucleation sites, providing greater access to the undercooled region for solidification studies. Levitation techniques provide the environment to study the fundamental behavior and thermophysical properties of liquid metals. During electromagnetic levitation experiments, magnetohydrodynamic flow is driven in the sample by the electromagnetic force field. This flow can have various effects …
Turbulent Mixers For Protein Folding Experiments, Venkatesh Inguva
Turbulent Mixers For Protein Folding Experiments, Venkatesh Inguva
Doctoral Dissertations
Protein folding studies require the development of micro-mixers that require less sample, mix at faster rates, and still provide a high signal to noise ratio. Chaotic to marginally turbulent micro-mixers are promising candidates for this application. In this study, various turbulence and unsteadiness generation concepts are explored that avoid cavitation. The mixing enhancements include flow turning regions, flow splitters, and vortex shedding. The relative effectiveness of these different approaches for rapid micro-mixing is discussed. Simulations found that flow turning regions provided the best mixing profile. Various turbulence models are simulated to determine appropriate model of the design requirements. Experimental validation …
Computational Exploration Of Flash-Boiling Internal Flow And Near-Nozzle Spray, Sampath K. Rachakonda
Computational Exploration Of Flash-Boiling Internal Flow And Near-Nozzle Spray, Sampath K. Rachakonda
Doctoral Dissertations
Gasoline engines operating under the principle of direct injection are susceptible to flash-boiling due to superheated nature of the fuel and the sub-atmospheric in-cylinder pressures during injection. A review of the literature on flash-boiling sprays shows that a majority of the studies have focused on the far-field regions of the spray, with limited attention given to understanding the influences of the injector geometry and the near-nozzle regions of the spray. Modeling the internal nozzle flow and the primary atomization, on which the far-field spray depends, is a challenge. This thesis, therefore, is aimed at understanding the complex flow through a …
Reduced Order Fluid-Structure Interaction Models For Thin Shells With Non-Zero Gaussian Curvatures To Understand The Response Of Aneurysms To Flow, Gary Han Chang
Doctoral Dissertations
In this thesis, a reduced-order model is constructed to study the physiological flow and wall shear stress conditions for aneurysms. The method of local proper orthogonal decomposition (POD) is used to construct the reduced-order modes using a series of CFD results, which are subsequently improved using a QR-factorization technique to satisfy the various boundary conditions in physiological flow problems. This method can effectively construct a computationally efficient physiological model, which allows us to examine the fluid velocities and wall shear stress distributions over a range of different physiological flow parameters. Aneurysms are the dilation, bulging, or ballooning-out of part of …
Eulerian Cfd Modeling Of Multiphase Internal Injector Flow And External Sprays, Eli T. Baldwin
Eulerian Cfd Modeling Of Multiphase Internal Injector Flow And External Sprays, Eli T. Baldwin
Doctoral Dissertations
The improvement of combustion systems which use sprays to atomize liquid fuel requires an understanding of that atomization process. Although the secondary break up mechanisms for the far-field of an atomizing spray have been thoroughly studied and well understood for some time, understanding the internal nozzle flow and primary atomization on which the far-field spray depends has proven to be more of a challenge. Flow through fuel injector nozzles can be highly complex and heavily influenced by factors such as turbulence, needle motion, nozzle imperfections, nozzle asymmetry, and phase change. All of this occurs within metallic injectors, making experimental characterization …
A Computational Study On Extension Of Non-Contact Modulation Calorimetry, Xiao Ye
A Computational Study On Extension Of Non-Contact Modulation Calorimetry, Xiao Ye
Doctoral Dissertations
ABSTRACT A COMPUTATIONAL STUDY ON EXTENSION OF NON-CONTACT MODULATION CALORIMETRY May 2015 XIAO YE B.S., SOUTHEAST UNIVERSITY M.S., UNIVERSITY OF MASSACHUSETTS, AMHERST Ph. D., UNIVERSITY OF MASSACHUSETTS, AMHERST Directed by: Professor Robert W. Hyers Accurate thermophysical properties of high temperature metallic liquids are important for both industrial applications and scientific research. For the former, as predictive numerical simulations play an increasingly important role in pivotal industries, such as casting, welding and sintering, the lack of precise thermophysical properties, especially at high temperatures, hamper their further applications. On the other hand, from the stand point of basic metals physics, being able …