+publisher:"University of Texas – Austin" +contributor:("Moser, Robert")

University of Texas – Austin

1. Smith, Tony Lee. May the best manipulator win : 2004 and 2010 Ukrainian presidential elections revisited.

Degree: MA, Government, 2014, University of Texas – Austin

► Ukraine is currently in the throes of revolution. Will this popular uprising move Ukraine closer to the West and a democratic government or strengthen the… (more)

Subjects/Keywords: Ukraine; Russia; Elections; Voter fraud; Electoral manipulation; Yushchenko; Yanukovich; Survey; List experiment; Ukraine county level administrators; Ukrainian politics; Ukrainian democratization

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APA (6^th Edition):

Smith, T. L. (2014). May the best manipulator win : 2004 and 2010 Ukrainian presidential elections revisited. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/26362

Chicago Manual of Style (16^th Edition):

Smith, Tony Lee. “May the best manipulator win : 2004 and 2010 Ukrainian presidential elections revisited.” 2014. Masters Thesis, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/26362.

MLA Handbook (7^th Edition):

Smith, Tony Lee. “May the best manipulator win : 2004 and 2010 Ukrainian presidential elections revisited.” 2014. Web. 24 Jan 2021.

Vancouver:

Smith TL. May the best manipulator win : 2004 and 2010 Ukrainian presidential elections revisited. [Internet] [Masters thesis]. University of Texas – Austin; 2014. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/26362.

Council of Science Editors:

Smith TL. May the best manipulator win : 2004 and 2010 Ukrainian presidential elections revisited. [Masters Thesis]. University of Texas – Austin; 2014. Available from: http://hdl.handle.net/2152/26362

University of Texas – Austin

2. Ulerich, Rhys David. Reducing turbulence- and transition-driven uncertainty in aerothermodynamic heating predictions for blunt-bodied reentry vehicles.

Degree: PhD, Computational Science, Engineering, and Mathematics, 2014, University of Texas – Austin

URL: http://hdl.handle.net/2152/26886

► Turbulent boundary layers approximating those found on the NASA Orion Multi-Purpose Crew Vehicle (MPCV) thermal protection system during atmospheric reentry from the International Space Station… (more)

▼ Turbulent boundary layers approximating those found on the NASA Orion Multi-Purpose Crew Vehicle (MPCV) thermal protection system during atmospheric reentry from the International Space Station have been studied by direct numerical simulation, with the ultimate goal of reducing aerothermodynamic heating prediction uncertainty. Simulations were performed using a new, well-verified, openly available Fourier/B-spline pseudospectral code called Suzerain equipped with a ``slow growth'' spatiotemporal homogenization approximation recently developed by Topalian et al. A first study aimed to reduce turbulence-driven heating prediction uncertainty by providing high-quality data suitable for calibrating Reynolds-averaged Navier – Stokes turbulence models to address the atypical boundary layer characteristics found in such reentry problems. The two data sets generated were Ma[approximate symbol] 0.9 and 1.15 homogenized boundary layers possessing Re[subscript theta, approximate symbol] 382 and 531, respectively. Edge-to-wall temperature ratios, T[subscript e]/T[subscript w], were close to 4.15 and wall blowing velocities, v[subscript w, superscript plus symbol]= v[subscript w]/u[subscript tau], were about 8 x 10-3 . The favorable pressure gradients had Pohlhausen parameters between 25 and 42. Skin frictions coefficients around 6 x10-3 and Nusselt numbers under 22 were observed. Near-wall vorticity fluctuations show qualitatively different profiles than observed by Spalart (J. Fluid Mech. 187 (1988)) or Guarini et al. (J. Fluid Mech. 414 (2000)). Small or negative displacement effects are evident. Uncertainty estimates and Favre-averaged equation budgets are provided. A second study aimed to reduce transition-driven uncertainty by determining where on the thermal protection system surface the boundary layer could sustain turbulence. Local boundary layer conditions were extracted from a laminar flow solution over the MPCV which included the bow shock, aerothermochemistry, heat shield surface curvature, and ablation. That information, as a function of leeward distance from the stagnation point, was approximated by Re[subscript theta], Ma[subscript e], [mathematical equation], v[subscript w, superscript plus sign], and T[subscript e]/T[subscript w] along with perfect gas assumptions. Homogenized turbulent boundary layers were initialized at those local conditions and evolved until either stationarity, implying the conditions could sustain turbulence, or relaminarization, implying the conditions could not. Fully turbulent fields relaminarized subject to conditions 4.134 m and 3.199 m leeward of the stagnation point. However, different initial conditions produced long-lived fluctuations at leeward position 2.299 m. Locations more than 1.389 m leeward of the stagnation point are predicted to sustain turbulence in this scenario. Advisors/Committee Members: Moser, Robert deLancey (advisor).

Subjects/Keywords: Atmospheric reentry; B-spline collocation; Channel flow; Cold wall; Direct numerical simulation; Energy perturbation method; Favorable pressure gradient; Flat plate; Homogenized boundary layer; Inviscid base flow; Isothermal wall; Low Reynolds number; Manufactured solution; NASA Orion; Negative displacement thickness; Predictive computation; Pseudospectral method; Radial nozzle; Reducing uncertainty; Reentry vehicle; Relaminarization; Sampling uncertainty; Simulation framework; Slow growth formulation; Software verification; Transition modeling; Turbulence budgets; Turbulent boundary layer; Wall blowing; Wall transpiration

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APA (6^th Edition):

Ulerich, R. D. (2014). Reducing turbulence- and transition-driven uncertainty in aerothermodynamic heating predictions for blunt-bodied reentry vehicles. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/26886

Chicago Manual of Style (16^th Edition):

Ulerich, Rhys David. “Reducing turbulence- and transition-driven uncertainty in aerothermodynamic heating predictions for blunt-bodied reentry vehicles.” 2014. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/26886.

MLA Handbook (7^th Edition):

Ulerich, Rhys David. “Reducing turbulence- and transition-driven uncertainty in aerothermodynamic heating predictions for blunt-bodied reentry vehicles.” 2014. Web. 24 Jan 2021.

Vancouver:

Ulerich RD. Reducing turbulence- and transition-driven uncertainty in aerothermodynamic heating predictions for blunt-bodied reentry vehicles. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2014. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/26886.

Council of Science Editors:

Ulerich RD. Reducing turbulence- and transition-driven uncertainty in aerothermodynamic heating predictions for blunt-bodied reentry vehicles. [Doctoral Dissertation]. University of Texas – Austin; 2014. Available from: http://hdl.handle.net/2152/26886

University of Texas – Austin

3. Goodnow, Regina Rose. Post-Soviet super-presidentialism : explaining constitutional choice in Russia and Ukraine.

Degree: PhD, Government, 2013, University of Texas – Austin

URL: http://hdl.handle.net/2152/28718

► The Russian and Ukrainian constitutions—like those in many other post-Soviet states—have concentrated political power in exclusive “super” presidencies. However, the concentration of power has persisted… (more)

▼ The Russian and Ukrainian constitutions—like those in many other post-Soviet states—have concentrated political power in exclusive “super” presidencies. However, the concentration of power has persisted in only one of the two cases. Russian presidential authority was resilient in the face of attempts to increase legislative strength in the 1990s, even when severe economic and political crises undermined the presidency of Boris Yeltsin. In contrast, Ukrainian presidential power fluctuated over time, with “Orange Revolution” constitutional reforms shifting power to the parliament in 2004 and their annulment returning power to the president in 2010. What explains the different trajectories of Russia’s and Ukraine’s presidential systems? Using process-tracing to parse out the actions of elites during the 1990s and 2000s in combination with analyses of the electoral foundations of elite competition in the two cases, this dissertation develops an argument about the origins of super-presidential systems and the prospects for constitutional change in such systems. Concentrated executive power in Russia and Ukraine: (1) depended on elites’ preferences for more or less concentrated political authority; (2) these preferences depended on how elites perceived their political prospects for capturing and holding presidential power; (3) elites’ perceptions of their prospects for gaining and holding presidential power were conditioned by the relative balance of power between major political forces; and (4) this balance of power was very vulnerable to pressure from social forces. It was this final factor that distinguished the Ukrainian and Russian cases. Ukraine had more balanced political competition because of its coherent ethno-linguistic cleavage, and consequently more uncertainty about rival elites’ political fortunes, which produced challenges to super-presidentialism. Russia’s experience with regional politics, by contrast, has not produced a similarly stable balance of power between rival forces, because the country’s minority groups were too diverse and dispersed to form a unified constituency that could challenge the political dominance of the center. The structural underpinnings of elite competition help to explain why the preferences of self-interested politicians to concentrate or disperse political power changed over time in ways that promoted unstable super-presidentialism in Ukraine compared to much more durable super-presidentialism in Russia. Advisors/Committee Members: Moser, Robert G., 1966- (advisor).

Subjects/Keywords: Russia; Ukraine; Presidentialism; Super-presidentialism; Constitutional choice; Constitutional change

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APA (6^th Edition):

Goodnow, R. R. (2013). Post-Soviet super-presidentialism : explaining constitutional choice in Russia and Ukraine. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/28718

Chicago Manual of Style (16^th Edition):

Goodnow, Regina Rose. “Post-Soviet super-presidentialism : explaining constitutional choice in Russia and Ukraine.” 2013. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/28718.

MLA Handbook (7^th Edition):

Goodnow, Regina Rose. “Post-Soviet super-presidentialism : explaining constitutional choice in Russia and Ukraine.” 2013. Web. 24 Jan 2021.

Vancouver:

Goodnow RR. Post-Soviet super-presidentialism : explaining constitutional choice in Russia and Ukraine. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2013. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/28718.

Council of Science Editors:

Goodnow RR. Post-Soviet super-presidentialism : explaining constitutional choice in Russia and Ukraine. [Doctoral Dissertation]. University of Texas – Austin; 2013. Available from: http://hdl.handle.net/2152/28718

University of Texas – Austin

4. Brooke, Steven Thomas. Exit, voice, and Islamic activism : organizational fracture and the Egyptian Society of the Muslim Brothers.

Degree: MA, Government, 2011, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2011-05-3353

► Under what conditions does the Egyptian Society of the Muslim Brothers (SMB) fracture? The 1996 formation of the Wasat party by a group of former… (more)

Subjects/Keywords: Muslim Brotherhood; Political opposition; Wasat party; Egypt; Islam; Party politics; Politics and government; Gamal Abdel Nasser; Islamic Action Front

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APA (6^th Edition):

Brooke, S. T. (2011). Exit, voice, and Islamic activism : organizational fracture and the Egyptian Society of the Muslim Brothers. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2011-05-3353

Chicago Manual of Style (16^th Edition):

Brooke, Steven Thomas. “Exit, voice, and Islamic activism : organizational fracture and the Egyptian Society of the Muslim Brothers.” 2011. Masters Thesis, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/ETD-UT-2011-05-3353.

MLA Handbook (7^th Edition):

Brooke, Steven Thomas. “Exit, voice, and Islamic activism : organizational fracture and the Egyptian Society of the Muslim Brothers.” 2011. Web. 24 Jan 2021.

Vancouver:

Brooke ST. Exit, voice, and Islamic activism : organizational fracture and the Egyptian Society of the Muslim Brothers. [Internet] [Masters thesis]. University of Texas – Austin; 2011. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/ETD-UT-2011-05-3353.

Council of Science Editors:

Brooke ST. Exit, voice, and Islamic activism : organizational fracture and the Egyptian Society of the Muslim Brothers. [Masters Thesis]. University of Texas – Austin; 2011. Available from: http://hdl.handle.net/2152/ETD-UT-2011-05-3353

University of Texas – Austin

5. Sorace, Christian Phillip. Beyond repair : state-society relations in the aftermath of the 2008 Wenchuan earthquake.

Degree: PhD, Government, 2014, University of Texas – Austin

URL: http://hdl.handle.net/2152/28070

► My dissertation offers insight into the political epistemology of the Chinese Communist Party and state on the basis of their activities during the post-2008 Wenchuan… (more)

▼ My dissertation offers insight into the political epistemology of the Chinese Communist Party and state on the basis of their activities during the post-2008 Wenchuan earthquake reconstruction. By “political epistemology,” I mean how the Party thinks about the nature of politics, including but not limited to the role of the state in the economy. An important facet of this approach is taking seriously the CCP’s distinctive manner of thinking, writing, and talking about politics that is too often dismissed as empty jargon that means little in post-Mao China. I show how a Maoist conception of politics remains at the bedrock of how the CCP understands its own political identity and actions. Certainly, many of the salient features of Maoism have been discarded, such as the emphasis on class struggle, continuous revolution, and the role of the masses in political movements. Despite these trends toward de-politicization and technocracy, the Party’s confidence in the rationality of its planning apparatus and in its ability to mobilize politically to achieve the ends of market construction and biopolitical social transformation constitutes what I call Maoist neo-developmentalism. Each of my empirical case chapters examines a localized combination of post-disaster reconstruction with a national strategy for long-term, “great leap” development. Thus, each chapter traces how the Party’s plans to capitalize the countryside - by way of urbanization, tourism, and ecology – have become stuck in transitional processes. The spectacular market transitions and transformations envisioned by Party leaders became cycles of state investment in local economies that only function by virtue of continued state involvement. The Party’s massive expenditures of maintaining the appearance of success, however, generated local resentment at perceived waste, indifference, and corruption. Each case chapter shows evidence not so much of social resistance to the state (although of course that happened, too) but an intimate negotiation between state and society of high expectations, broken promises, and frustrations. I argue that these “perforations” deep within the tissue of the state-society relationship only make sense when viewed from the context of a Maoist social contact in which the Party’s legitimacy depends on its perceived ability to serve the people. Advisors/Committee Members: Moser, Robert G., 1966- (advisor), Hurst, William, 1975- (advisor).

Subjects/Keywords: China; Comparative politics; Post-disaster reconstruction; Rural political economy; Discursive analysis; Ideational behavior of authoritarian states; Maoist ideology

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APA (6^th Edition):

Sorace, C. P. (2014). Beyond repair : state-society relations in the aftermath of the 2008 Wenchuan earthquake. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/28070

Chicago Manual of Style (16^th Edition):

Sorace, Christian Phillip. “Beyond repair : state-society relations in the aftermath of the 2008 Wenchuan earthquake.” 2014. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/28070.

MLA Handbook (7^th Edition):

Sorace, Christian Phillip. “Beyond repair : state-society relations in the aftermath of the 2008 Wenchuan earthquake.” 2014. Web. 24 Jan 2021.

Vancouver:

Sorace CP. Beyond repair : state-society relations in the aftermath of the 2008 Wenchuan earthquake. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2014. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/28070.

Council of Science Editors:

Sorace CP. Beyond repair : state-society relations in the aftermath of the 2008 Wenchuan earthquake. [Doctoral Dissertation]. University of Texas – Austin; 2014. Available from: http://hdl.handle.net/2152/28070

6. Chan, Jesse L. A DPG method for convection-diffusion problems.

Degree: PhD, Computational and Applied Mathematics, 2013, University of Texas – Austin

URL: http://hdl.handle.net/2152/21417

► Over the last three decades, CFD simulations have become commonplace as a tool in the engineering and design of high-speed aircraft. Experiments are often complemented… (more)

▼ Over the last three decades, CFD simulations have become commonplace as a tool in the engineering and design of high-speed aircraft. Experiments are often complemented by computational simulations, and CFD technologies have proved very useful in both the reduction of aircraft development cycles, and in the simulation of conditions difficult to reproduce experimentally. Great advances have been made in the field since its introduction, especially in areas of meshing, computer architecture, and solution strategies. Despite this, there still exist many computational limitations in existing CFD methods; in particular, reliable higher order and hp-adaptive methods for the Navier-Stokes equations that govern viscous compressible flow. Solutions to the equations of viscous flow can display shocks and boundary layers, which are characterized by localized regions of rapid change and high gradients. The use of adaptive meshes is crucial in such settings – good resolution for such problems under uniform meshes is computationally prohibitive and impractical for most physical regimes of interest. However, the construction of "good" meshes is a difficult task, usually requiring a-priori knowledge of the form of the solution. An alternative to such is the construction of automatically adaptive schemes; such methods begin with a coarse mesh and refine based on the minimization of error. However, this task is difficult, as the convergence of numerical methods for problems in CFD is notoriously sensitive to mesh quality. Additionally, the use of adaptivity becomes more difficult in the context of higher order and hp methods. Many of the above issues are tied to the notion of robustness, which we define loosely for CFD applications as the degradation of the quality of numerical solutions on a coarse mesh with respect to the Reynolds number, or nondimensional viscosity. For typical physical conditions of interest for the compressible Navier-Stokes equations, the Reynolds number dictates the scale of shock and boundary layer phenomena, and can be extremely high – on the order of 10⁷ in a unit domain. For an under-resolved mesh, the Galerkin finite element method develops large oscillations which prevent convergence and pollute the solution. The issue of robustness for finite element methods was addressed early on by Brooks and Hughes in the SUPG method, which introduced the idea of residual-based stabilization to combat such oscillations. Residual-based stabilizations can alternatively be viewed as modifying the standard finite element test space, and consequently the norm in which the finite element method converges. Demkowicz and Gopalakrishnan generalized this idea in 2009 by introducing the Discontinous Petrov-Galerkin (DPG) method with optimal test functions, where test functions are determined such that they minimize the discrete linear residual in a dual space. Under the ultra-weak variational formulation, these test functions can be computed locally to yield a symmetric, positive-definite system. The main… Advisors/Committee Members: Demkowicz, Leszek (advisor), Moser, Robert deLancey (advisor).

Subjects/Keywords: Finite element methods; Discontinuous Galerkin; Petrov-Galerkin; Optimal test functions; Minimum residual methods; Convection-diffusion; Compressible flow

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APA (6^th Edition):

Chan, J. L. (2013). A DPG method for convection-diffusion problems. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/21417

Chicago Manual of Style (16^th Edition):

Chan, Jesse L. “A DPG method for convection-diffusion problems.” 2013. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/21417.

MLA Handbook (7^th Edition):

Chan, Jesse L. “A DPG method for convection-diffusion problems.” 2013. Web. 24 Jan 2021.

Vancouver:

Chan JL. A DPG method for convection-diffusion problems. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2013. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/21417.

Council of Science Editors:

Chan JL. A DPG method for convection-diffusion problems. [Doctoral Dissertation]. University of Texas – Austin; 2013. Available from: http://hdl.handle.net/2152/21417

University of Texas – Austin

7. Beirnaert-Chartrel, Gwennaël. CFD predictions of heat transfer coefficient augmentation on a simulated film cooled turbine blade leading edge.

Degree: MSin Engineering, Mechanical Engineering, 2011, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2011-05-3427

► Computations were run to study heat transfer coefficient augmentation with film cooling for a simulated gas turbine blade leading edge. The realizable k-[epsilon] turbulence model… (more)

Subjects/Keywords: Film cooling; Gas turbine; Turbine blade; Heat transfer coefficient augmentation; CFD; RANS simulations; Turbulence

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Beirnaert-Chartrel, G. (2011). CFD predictions of heat transfer coefficient augmentation on a simulated film cooled turbine blade leading edge. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2011-05-3427

Chicago Manual of Style (16^th Edition):

Beirnaert-Chartrel, Gwennaël. “CFD predictions of heat transfer coefficient augmentation on a simulated film cooled turbine blade leading edge.” 2011. Masters Thesis, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/ETD-UT-2011-05-3427.

MLA Handbook (7^th Edition):

Beirnaert-Chartrel, Gwennaël. “CFD predictions of heat transfer coefficient augmentation on a simulated film cooled turbine blade leading edge.” 2011. Web. 24 Jan 2021.

Vancouver:

Beirnaert-Chartrel G. CFD predictions of heat transfer coefficient augmentation on a simulated film cooled turbine blade leading edge. [Internet] [Masters thesis]. University of Texas – Austin; 2011. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/ETD-UT-2011-05-3427.

Council of Science Editors:

Beirnaert-Chartrel G. CFD predictions of heat transfer coefficient augmentation on a simulated film cooled turbine blade leading edge. [Masters Thesis]. University of Texas – Austin; 2011. Available from: http://hdl.handle.net/2152/ETD-UT-2011-05-3427

8. Kabacaoğlu, Gökberk. Numerical methods for simulations and optimization of vesicle flows in microfluidic devices.

Degree: PhD, Mechanical Engineering, 2019, University of Texas – Austin

URL: http://dx.doi.org/10.26153/tsw/2875

► Vesicles are highly deformable particles that are filled with a Newtonian fluid. They resemble biological cells without a nucleus such as red blood cells (RBCs).… (more)

▼ Vesicles are highly deformable particles that are filled with a Newtonian fluid. They resemble biological cells without a nucleus such as red blood cells (RBCs). Vesicle flow simulations can be used to design microfluidic devices for medical diagnoses and drug delivery systems. This dissertation focuses on efficient numerical methods for simulations and optimization of vesicle flows in two dimensions. We consider flows with very low Reynolds numbers and inextensible vesicle membranes that resist bending. Our numerical scheme is based on a boundary integral formulation which is known to be efficient for such flows. This formulation leads to a set of nonlinear integro-differential equations for the vesicle dynamics. Complex interplay between the nonlocal hydrodynamic forces and the membranes’ elasticity determines the vesicles’ motion. Many state-of-the-art numerical schemes can resolve these complex flows. However, simulations remain computationally expensive since high-resolution discretization is needed. The high computational cost limits the use of the simulations for practical purposes such as optimization. Our first attempt to reduce the cost is to use low-resolution discretization. We present a scheme that systematically integrates several correction algorithms that are necessary for stable and accurate low-resolution simulations. We compare the low-resolution simulations with their high-fidelity counterparts. We observe that our scheme enables both fast and statistically accurate simulations. We accelerate vesicle flow simulations further by replacing expensive parts of the numerical scheme with low-cost function approximations. We propose a machine-learning-augmented reduced model that uses several multilayer perceptrons to model different aspects of the flows. Although we train the perceptrons with high-fidelity single-particle simulations for one time step, our method enables us to conduct long-horizon simulations of suspensions with several particles in confined geometries. It is faster than a state-of-the-art numerical scheme having the same number of degrees of freedom and can reproduce several features of the flow accurately. It generalizes as is to other particles like deformable capsules, drops, filaments and rigid bodies. Moreover, we investigate deformability-based sorting of RBCs using a microfluidic device that enables medical diagnoses of diseases such as malaria. Using our numerical scheme we solve a design optimization problem to find optimal designs of the device that provide efficient sorting of cells with arbitrary mechanical properties Advisors/Committee Members: Biros, George (advisor), Ghattas, Omar (committee member), Moser, Robert (committee member), Shelley, Michael (committee member).

Subjects/Keywords: Computational biology; Fluid dynamics; Fast algorithms; Machine learning

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APA (6^th Edition):

Kabacaoğlu, G. (2019). Numerical methods for simulations and optimization of vesicle flows in microfluidic devices. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://dx.doi.org/10.26153/tsw/2875

Chicago Manual of Style (16^th Edition):

Kabacaoğlu, Gökberk. “Numerical methods for simulations and optimization of vesicle flows in microfluidic devices.” 2019. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://dx.doi.org/10.26153/tsw/2875.

MLA Handbook (7^th Edition):

Kabacaoğlu, Gökberk. “Numerical methods for simulations and optimization of vesicle flows in microfluidic devices.” 2019. Web. 24 Jan 2021.

Vancouver:

Kabacaoğlu G. Numerical methods for simulations and optimization of vesicle flows in microfluidic devices. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2019. [cited 2021 Jan 24]. Available from: http://dx.doi.org/10.26153/tsw/2875.

Council of Science Editors:

Kabacaoğlu G. Numerical methods for simulations and optimization of vesicle flows in microfluidic devices. [Doctoral Dissertation]. University of Texas – Austin; 2019. Available from: http://dx.doi.org/10.26153/tsw/2875

University of Texas – Austin

9. Wahal, Siddhant. Novel algorithms for Uncertainty Quantification in large scale systems.

Degree: PhD, Computational Science, Engineering, and Mathematics, 2020, University of Texas – Austin

URL: http://dx.doi.org/10.26153/tsw/10158

► Uncertainty Quantification (UQ) algorithms are of increasing significance in science and engineering. The process of modeling physical reality on computers is rife with uncertainties. These… (more)

▼ Uncertainty Quantification (UQ) algorithms are of increasing significance in science and engineering. The process of modeling physical reality on computers is rife with uncertainties. These uncertainties get propagated through the computer model, leading to uncertain outputs. As decision-makers from every facet of society come to increasingly rely on computer predictions, the need to characterize this uncertainty has never been greater. However, doing so efficiently remains challenging. This is primarily because computer models are often time consuming to run and because their inputs live in high-dimensional spaces that are difficult to explore. In this thesis, we seek to address this challenge in the context of two UQ problems. In the first UQ problem, we study rare-event simulation: given a smooth non-linear map with uncertain inputs, what is the probability that the output evaluates inside a specified interval? Standard statistical approaches for computing this probability, such as the Monte Carlo method, become computationally inefficient as the event under consideration becomes rare. To address this inefficiency, we present two Importance Sampling (IS) algorithms. Our first algorithm, called the Bayesian Inverse Monte Carlo (BIMC) method, relies on solving a fictitious Bayesian inverse problem. The solution of the inverse problem yields a posterior PDF, a local Gaussian approximation to which serves as the importance sampling density. We subject BIMC to rigorous theoretical and experimental analysis, which establishes that BIMC can lead to speedups of several orders-of-magnitude (over the Monte Carlo method) when the forward map is nearly affine, or weakly non-linear. When these conditions are violated, that is, when the forward map is significantly nonlinear, BIMC leads to a poor-quality IS distribution. Motivated by these limitations, we propose modifications to BIMC. The modified algorithm, which we term Adaptive-BIMC (A-BIMC), proceeds in two stages. The first stage roughly identifies those regions in input space that trigger a rare event. The second stage then refines the approximation from the first stage of the algorithm. We study A-BIMC’s performance on synthetic problems and demonstrate that its performance doesn’t depend on how small the target probability is. Rather it depends on the nonlinearity of the input-output map. Through these experiments, we also find that A-BIMC’s performance deteriorates with increasing ambient dimensionality of the problem. To address this issue, we lay the foundation for a general dimension reduction strategy for rare-event probability estimation. The second UQ problem concerns the statistical calibration of model inputs from observed data, with the ultimate aim of issuing uncertainty-equipped predictions of a Quantity-of- Interest (QoI). The physical system that we study here is a hydrocarbon reservoir containing geological faults. Operational decisions concerning the reservoir rely on predictions of financial summaries of the reservoir, such as its Net Present Value.… Advisors/Committee Members: Biros, George (advisor), Marzouk, Youssef (committee member), Ghattas, Omar N (committee member), Moser, Robert D (committee member), Mueller, Peter (committee member).

Subjects/Keywords: Uncertainty quantification; Bayesian inference; Importance sampling; Rare events

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APA (6^th Edition):

Wahal, S. (2020). Novel algorithms for Uncertainty Quantification in large scale systems. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://dx.doi.org/10.26153/tsw/10158

Chicago Manual of Style (16^th Edition):

Wahal, Siddhant. “Novel algorithms for Uncertainty Quantification in large scale systems.” 2020. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://dx.doi.org/10.26153/tsw/10158.

MLA Handbook (7^th Edition):

Wahal, Siddhant. “Novel algorithms for Uncertainty Quantification in large scale systems.” 2020. Web. 24 Jan 2021.

Vancouver:

Wahal S. Novel algorithms for Uncertainty Quantification in large scale systems. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2020. [cited 2021 Jan 24]. Available from: http://dx.doi.org/10.26153/tsw/10158.

Council of Science Editors:

Wahal S. Novel algorithms for Uncertainty Quantification in large scale systems. [Doctoral Dissertation]. University of Texas – Austin; 2020. Available from: http://dx.doi.org/10.26153/tsw/10158

10. Ellis, Truman Everett. Space-time discontinuous Petrov-Galerkin finite elements for transient fluid mechanics.

Degree: PhD, Computational science, engineering, and mathematics, 2016, University of Texas – Austin

URL: http://hdl.handle.net/2152/43588

► Initial mesh design for computational fluid dynamics can be a time-consuming and expensive process. The stability properties and nonlinear convergence of most numerical methods rely… (more)

▼ Initial mesh design for computational fluid dynamics can be a time-consuming and expensive process. The stability properties and nonlinear convergence of most numerical methods rely on a minimum level of mesh resolution. This means that unless the initial computational mesh is fine enough, convergence can not be guaranteed. Any meshes below this minimum resolution level are termed to be in the ``pre-asymptotic regime.'' This condition implies that meshes need to in some way anticipate the solution before it is known. On top of the minimum requirement that the surface meshes must adequately represent the geometry of the problem under consideration, resolution requirements on the volume mesh make the CFD practitioner's job significantly more time consuming. In contrast to most other numerical methods, the discontinuous Petrov-Galerkin finite element method retains exceptional stability on extremely coarse meshes. DPG is also inherently very adaptive. It is possible to compute the residual error without knowledge of the exact solution, which can be used to robustly drive adaptivity. This results in a very automated technology, as the user can initialize a computation on the coarsest mesh which adequately represents the geometry then step back and let the program solve and adapt iteratively until it resolves the solution features. A common complaint of minimum residual methods by computational fluid dynamics practitioners is that they are not locally conservative. In this thesis, this concern is addressed by developing a locally conservative DPG formulation by augmenting the system with Lagrange multipliers. The resulting DPG formulation is then proved to be robust and shown to produce superior numerical results over standard DPG on a selection of test problems. Adaptive convergence to steady incompressible and compressible Navier-Stokes solutions was explored in Jesse Chan's and Nathan Roberts' dissertations. Space-time offers a natural extension to transient problems as it preserves the stability and adaptivity properties of DPG in the time dimension. Space-time also offers more extensive parallelization capability than problems treated with traditional time stepping as it allows multigrid concurrently in both space and time. A proof of concept space-time DPG formulation is developed for transient convection-diffusion. The robust test norms derived for steady convection-diffusion are extended to the space-time case and proofs of robustness are provided. Numerical results verify the robust behavior and near L² optimality of the resulting solutions. The space-time formulation for convection-diffusion is then extended to transient incompressible and compressible Navier-Stokes by analogy. Several numerical experiments are performed, but a mathematical analysis is not attempted for these nonlinear problems. Several side topics are explored such as a study of the compressible Navier-Stokes equations under various variable transformations and the development of consistent test norms through the concept of physical… Advisors/Committee Members: Demkowicz, Leszek (advisor), Moser, Robert D (advisor), Hughes, Thomas J.R (committee member), Dawson, Clint N (committee member), Bui, Tan (committee member).

Subjects/Keywords: Space-time; Finite elements; Discontinuous Petrov-Galerkin; Navier-Stokes; Local conservation

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APA (6^th Edition):

Ellis, T. E. (2016). Space-time discontinuous Petrov-Galerkin finite elements for transient fluid mechanics. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/43588

Chicago Manual of Style (16^th Edition):

Ellis, Truman Everett. “Space-time discontinuous Petrov-Galerkin finite elements for transient fluid mechanics.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/43588.

MLA Handbook (7^th Edition):

Ellis, Truman Everett. “Space-time discontinuous Petrov-Galerkin finite elements for transient fluid mechanics.” 2016. Web. 24 Jan 2021.

Vancouver:

Ellis TE. Space-time discontinuous Petrov-Galerkin finite elements for transient fluid mechanics. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/43588.

Council of Science Editors:

Ellis TE. Space-time discontinuous Petrov-Galerkin finite elements for transient fluid mechanics. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/43588

University of Texas – Austin

11. -1913-0932. Resisting ethnic cleansing : Crimean Tatars, Crimea, and the Soviet Union, 1941-1991.

Degree: PhD, History, 2017, University of Texas – Austin

URL: http://dx.doi.org/10.26153/tsw/5782

► “Resisting Ethnic Cleansing: Crimean Tatars Against and Within the Soviet Union, 1944-1991,” examines Stalin’s multifaceted ethnic cleansing of the Crimean Peninsula and how the region’s… (more)

▼ “Resisting Ethnic Cleansing: Crimean Tatars Against and Within the Soviet Union, 1944-1991,” examines Stalin’s multifaceted ethnic cleansing of the Crimean Peninsula and how the region’s largest ethnic group, Crimean Tatars, created a decades-long protest movement to resist each aspect of Stalin’s policy. First, I argue that Stalin’s deportation and exile of Crimean Tatars amounted to a bureaucratic genocide: a Soviet iteration on state violence that used inefficiency, irresponsibility, confusion, and loyalty to the system to destroy the national and class “enemies” of the Soviet Union. Second, this study emphasizes how ethnic cleansing in Crimea was extraordinary in the way Soviet power transformed Crimea after the deportations. From 1944 to 1954, this transformation created a “new Russian Crimea” through policies of mass settlement, land redistribution, and renaming geographic locations and rewriting history. Third, having revealed the full extent Stalin’s project, I explore how Crimean Tatars created the largest protest movement in the postwar Soviet Union. Throughout the 1960s and 1970s, Crimean Tatar activists and everyday citizens established contacts with Soviet dissidents and Western human rights activists to create a transnational protest movement. Through this network, a small, repressed nation demanded specific changes from what was one of the world’s most complex state bureaucracies and framed their arguments within the international language of protest and human rights. They accomplished their main goal, and returned to Crimea as the Soviet Union collapsed. Overall, this project highlights how activists can incorporate the ideas and language of post-Nuremburg human rights into practical actions and how ordinary citizens can work simultaneously within and outside of a system to resist a repressive police state. Advisors/Committee Members: Wynn, Charters, 1953- (advisor), Neuberger, Joan (committee member), Suri, Jeremi (committee member), Neuburger, Mary (committee member), Moser, Robert (committee member).

Subjects/Keywords: Crimean Tatars; Crimea; Soviet Union; Genocide; World War II; Ethnic cleansing; Protest; Resistance

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APA (6^th Edition):

-1913-0932. (2017). Resisting ethnic cleansing : Crimean Tatars, Crimea, and the Soviet Union, 1941-1991. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://dx.doi.org/10.26153/tsw/5782

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Chicago Manual of Style (16^th Edition):

-1913-0932. “Resisting ethnic cleansing : Crimean Tatars, Crimea, and the Soviet Union, 1941-1991.” 2017. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://dx.doi.org/10.26153/tsw/5782.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

MLA Handbook (7^th Edition):

-1913-0932. “Resisting ethnic cleansing : Crimean Tatars, Crimea, and the Soviet Union, 1941-1991.” 2017. Web. 24 Jan 2021.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Vancouver:

-1913-0932. Resisting ethnic cleansing : Crimean Tatars, Crimea, and the Soviet Union, 1941-1991. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2017. [cited 2021 Jan 24]. Available from: http://dx.doi.org/10.26153/tsw/5782.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Council of Science Editors:

-1913-0932. Resisting ethnic cleansing : Crimean Tatars, Crimea, and the Soviet Union, 1941-1991. [Doctoral Dissertation]. University of Texas – Austin; 2017. Available from: http://dx.doi.org/10.26153/tsw/5782

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

University of Texas – Austin

12. Yang, Shan. A shape Hessian-based analysis of roughness effects on fluid flows.

Degree: PhD, Computational and Applied Mathematics, 2011, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2011-08-4036

► The flow of fluids over solid surfaces is an integral part of many technologies, and the analysis of such flows is important to the design… (more)

▼ The flow of fluids over solid surfaces is an integral part of many technologies, and the analysis of such flows is important to the design and operation of these technologies. Solid surfaces, however, are generally rough at some scale, and analyzing the effects of such roughness on fluid flows represents a significant challenge. There are two fluid flow situations in which roughness is particularly important, because the fluid shear layers they create can be very thin, of order the height of the roughness. These are very high Reynolds number turbulent wall-bounded flows (the viscous wall layer is very thin), and very low Reynolds number lubrication flows (the lubrication layer between moving surfaces is very thin). Analysis in both of these flow domains has long accounted for roughness through empirical adjustments to the smooth-wall analysis, with empirical parameters describing the fluid dynamic roughness effects. The ability to determine these effects from a topographic description of the roughness is limited (lubrication) or non-existent (turbulence). The commonly used parameter, the equivalent sand grain roughness, can be determined in terms of the change in the rate of viscous energy dissipation caused by the roughness and is generally obtained by measuring the effects on a fluid flow. However, determining fluid dynamic effects from roughness characteristics is critical to effective engineering analysis. Characterization of this mapping from roughness topography to fluid dynamic impact is the main topic of the dissertation. Using the mathematical tools of shape calculus, we construct this mapping by defining the roughness functional and derive its first- and second- order shape derivatives, i.e., the derivatives of the roughness functional with respect to the roughness topography. The results of the shape gradient and complete spectrum of the shape Hessian are presented for the low Reynolds number lubrication flows. Flow predictions based on this derivative information is shown to be very accurate for small roughness. However, for the study of high Reynolds number turbulent flows, the direct extension of the current approach fails due to the chaotic nature of turbulent flows. Challenges and possible approaches are discussed for the turbulence problem as well as a model problem, the sensitivity analysis of the Lorenz system. Advisors/Committee Members: Ghattas, Omar N. (advisor), Moser, Robert deLancey (advisor), Arbogast, Todd (committee member), Goldstein, David (committee member), Ying, Lexing (committee member).

Subjects/Keywords: Roughness analysis; Shape calculus; Navier-Stokes flow

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APA (6^th Edition):

Yang, S. (2011). A shape Hessian-based analysis of roughness effects on fluid flows. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2011-08-4036

Chicago Manual of Style (16^th Edition):

Yang, Shan. “A shape Hessian-based analysis of roughness effects on fluid flows.” 2011. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/ETD-UT-2011-08-4036.

MLA Handbook (7^th Edition):

Yang, Shan. “A shape Hessian-based analysis of roughness effects on fluid flows.” 2011. Web. 24 Jan 2021.

Vancouver:

Yang S. A shape Hessian-based analysis of roughness effects on fluid flows. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2011. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/ETD-UT-2011-08-4036.

Council of Science Editors:

Yang S. A shape Hessian-based analysis of roughness effects on fluid flows. [Doctoral Dissertation]. University of Texas – Austin; 2011. Available from: http://hdl.handle.net/2152/ETD-UT-2011-08-4036

University of Texas – Austin

13. Strand, James Stephen. Statistical methods for the analysis of DSMC simulations of hypersonic shocks.

Degree: PhD, Aerospace Engineering, 2012, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2012-05-5384

► In this work, statistical techniques were employed to study the modeling of a hypersonic shock with the Direct Simulation Monte Carlo (DSMC) method, and to… (more)

▼ In this work, statistical techniques were employed to study the modeling of a hypersonic shock with the Direct Simulation Monte Carlo (DSMC) method, and to gain insight into how the model interacts with a set of physical parameters. Direct Simulation Monte Carlo (DSMC) is a particle based method which is useful for simulating gas dynamics in rarefied and/or highly non-equilibrium flowfields. A DSMC code was written and optimized for use in this research. The code was developed with shock tube simulations in mind, and it includes a number of improvements which allow for the efficient simulation of 1D, hypersonic shocks. Most importantly, a moving sampling region is used to obtain an accurate steady shock profile from an unsteady, moving shock wave. The code is MPI parallel and an adaptive load balancing scheme ensures that the workload is distributed properly between processors over the course of a simulation. Global, Monte Carlo based sensitivity analyses were performed in order to determine which of the parameters examined in this work most strongly affect the simulation results for two scenarios: a 0D relaxation from an initial high temperature state and a hypersonic shock. The 0D relaxation scenario was included in order to examine whether, with appropriate initial conditions, it can be viewed in some regards as a substitute for the 1D shock in a statistical sensitivity analysis. In both analyses sensitivities were calculated based on both the square of the Pearson correlation coefficient and the mutual information. The quantity of interest (QoI) chosen for these analyses was the NO density profile. This vector QoI was broken into a set of scalar QoIs, each representing the density of NO at a specific point in time (for the relaxation) or a specific streamwise location (for the shock), and sensitivities were calculated for each scalar QoI based on both measures of sensitivity. The sensitivities were then integrated over the set of scalar QoIs to determine an overall sensitivity for each parameter. A weighting function was used in the integration in order to emphasize sensitivities in the region of greatest thermal and chemical non-equilibrium. The six parameters which most strongly affect the NO density profile were found to be the same for both scenarios, which provides justification for the claim that a 0D relaxation can in some situations be used as a substitute model for a hypersonic shock. These six parameters are the pre-exponential constants in the Arrhenius rate equations for the N2 dissociation reaction N2 + N ⇄ 3N, the O2 dissociation reaction O2 + O ⇄ 3O, the NO dissociation reactions NO + N ⇄ 2N + O and NO + O ⇄ N + 2O, and the exchange reactions N2 + O ⇄ NO + N and NO + O ⇄ O2 + N. After identification of the most sensitive parameters, a synthetic data calibration was performed to demonstrate that the statistical inverse problem could be solved for the 0D relaxation scenario. The calibration was performed using the QUESO code, developed at the PECOS center at UT… Advisors/Committee Members: Goldstein, David Benjamin, doctor of aeronautics (advisor), Moser, Robert (committee member), Varghese, Philip (committee member), Ezekoye, Ofodike (committee member), Prudencio, Ernesto (committee member).

Subjects/Keywords: DSMC; MCMC; Sensitivity analysis

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APA (6^th Edition):

Strand, J. S. (2012). Statistical methods for the analysis of DSMC simulations of hypersonic shocks. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2012-05-5384

Chicago Manual of Style (16^th Edition):

Strand, James Stephen. “Statistical methods for the analysis of DSMC simulations of hypersonic shocks.” 2012. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/ETD-UT-2012-05-5384.

MLA Handbook (7^th Edition):

Strand, James Stephen. “Statistical methods for the analysis of DSMC simulations of hypersonic shocks.” 2012. Web. 24 Jan 2021.

Vancouver:

Strand JS. Statistical methods for the analysis of DSMC simulations of hypersonic shocks. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2012. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/ETD-UT-2012-05-5384.

Council of Science Editors:

Strand JS. Statistical methods for the analysis of DSMC simulations of hypersonic shocks. [Doctoral Dissertation]. University of Texas – Austin; 2012. Available from: http://hdl.handle.net/2152/ETD-UT-2012-05-5384

University of Texas – Austin

14. Kamensky, David Michael. Immersogeometric fluid–structure interaction analysis of bioprosthetic heart valves.

Degree: PhD, Computational science, engineering, and mathematics, 2016, University of Texas – Austin

URL: http://hdl.handle.net/2152/46874

► The purpose of this dissertation is to develop numerical methods for fluid–structure interaction (FSI) analysis that are suitable for modeling and simulating bioprosthetic heart valves… (more)

▼ The purpose of this dissertation is to develop numerical methods for fluid–structure interaction (FSI) analysis that are suitable for modeling and simulating bioprosthetic heart valves (BHVs). BHVs are prosthetic replacements for the valves that regulate blood flow through the heart. BHVs reproduce natural hemodynamic conditions by mimicking the structure of native heart valves: they consist of thin flexible leaflets, passively driven by interaction with surrounding fluid. Current designs frequently require replacement 10–15 years after implantation. Computer simulation may help identify causes of and solutions to durability issues. Despite much previous research into computer simulation of heart valve FSI, inconvenience or inaccuracy of readily available numerical methods have prevented widespread incorporation of FSI into models of heart valve mechanics. Challenges associated with heart valve FSI simulation include large deformations of the region occupied by fluid, with changes of topology as the valve opens and closes, and low mass of the structure relative to the fluid, which necessitates careful treatment of fluid–structure coupling. The presence of large pressure gradients also requires special attention to the treatment of fluid mass conservation. Further, a useful numerical method for studying and improving designs of BHVs should be able to capture variations of valve geometry without requiring major effort to construct geometry-specific discretizations. To meet these challenges, I develop a new numerical approach, combining the immersed boundary concept of capturing fluid–structure interfaces on unfitted discretizations with recent developments in isogeometric analysis (IGA), which directly uses geometrical designs of engineered systems as discrete analysis meshes. In this work, I immerse an isogeometric structure discretization into an unfitted analysis mesh of the fluid subproblem. I refer to the immersion of design geometries into unfitted analysis meshes as immersogeometric analysis. To reliably couple unfitted discretizations of the fluid and structure subproblems, I introduce a new semi-implicit time integration procedure and analyze its stability and convergence in the context of linear model problems. I verify that this analysis extrapolates to the nonlinear setting through numerical experiments and explore the validity of my modeling assumptions by comparing computer simulations with observations from an in vitro experiment. Advisors/Committee Members: Sacks, Michael S. (advisor), Hughes, Thomas J. R. (advisor), Ghattas, Omar (committee member), Moser, Robert D (committee member), Hsu, Ming-Chen (committee member).

Subjects/Keywords: Fluid–structure interaction; Isogeometric analysis; Immersogeometric analysis

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APA (6^th Edition):

Kamensky, D. M. (2016). Immersogeometric fluid–structure interaction analysis of bioprosthetic heart valves. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/46874

Chicago Manual of Style (16^th Edition):

Kamensky, David Michael. “Immersogeometric fluid–structure interaction analysis of bioprosthetic heart valves.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/46874.

MLA Handbook (7^th Edition):

Kamensky, David Michael. “Immersogeometric fluid–structure interaction analysis of bioprosthetic heart valves.” 2016. Web. 24 Jan 2021.

Vancouver:

Kamensky DM. Immersogeometric fluid–structure interaction analysis of bioprosthetic heart valves. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/46874.

Council of Science Editors:

Kamensky DM. Immersogeometric fluid–structure interaction analysis of bioprosthetic heart valves. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/46874

University of Texas – Austin

15. Koo, Heeseok. Large-eddy simulations of scramjet engines.

Degree: PhD, Aerospace Engineering, 2011, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2011-05-3203

► The main objective of this dissertation is to develop large-eddy simulation (LES) based computational tools for supersonic inlet and combustor design. In the recent past,… (more)

▼ The main objective of this dissertation is to develop large-eddy simulation (LES) based computational tools for supersonic inlet and combustor design. In the recent past, LES methodology has emerged as a viable tool for modeling turbulent combustion. LES computes the large scale mixing process accurately, thereby providing a better starting point for small-scale models that describe the combustion process. In fact, combustion models developed in the context of Reynolds-averaged Navier Stokes (RANS) equations exhibit better predictive capability when used in the LES framework. The development of a predictive computational tool based on LES will provide a significant boost to the design of scramjet engines. Although LES has been used widely in the simulation of subsonic turbulent flows, its application to high-speed flows has been hampered by a variety of modeling and numerical issues. In this work, we develop a comprehensive LES methodology for supersonic flows, focusing on the simulation of scramjet engine components. This work is divided into three sections. First, a robust compressible flow solver for a generalized high-speed flow configuration is developed. By using carefully designed numerical schemes, dissipative errors associated with discretization methods for high-speed flows are minimized. Multiblock and immersed boundary method are used to handle scramjet-specific geometries. Second, a new combustion model for compressible reactive flows is developed. Subsonic combustion models are not directly applicable in high-speed flows due to the coupling between the energy and velocity fields. Here, a probability density function (PDF) approach is developed for high-speed combustion. This method requires solution to a high dimensional PDF transport equation, which is achieved through a novel direct quadrature method of moments (DQMOM). The combustion model is validated using experiments on supersonic reacting flows. Finally, the LES methodology is used to study the inlet-isolator component of a dual-mode scramjet. The isolator is a critical component that maintains the compression shock structures required for stable combustor operation in ramjet mode. We simulate unsteady dynamics inside an experimental isolator, including the propagation of an unstart event that leads to loss of compression. Using a suite of simulations, the sensitivity of the results to LES models and numerical implementation is studied. Advisors/Committee Members: Raman, Venkat (advisor), Varghese, Philip L. (committee member), Clemens, Noel T. (committee member), Moser, Robert D. (committee member), Ezekoye, Ofodike A. (committee member).

Subjects/Keywords: Large-eddy simulations; Combustion model; DQMOM; Direct quadrature method of moments; Compressible flow; Shock capturing method; Hyperviscosity; Scramjet; Inlet-isolator; Unstart

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APA (6^th Edition):

Koo, H. (2011). Large-eddy simulations of scramjet engines. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2011-05-3203

Chicago Manual of Style (16^th Edition):

Koo, Heeseok. “Large-eddy simulations of scramjet engines.” 2011. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/ETD-UT-2011-05-3203.

MLA Handbook (7^th Edition):

Koo, Heeseok. “Large-eddy simulations of scramjet engines.” 2011. Web. 24 Jan 2021.

Vancouver:

Koo H. Large-eddy simulations of scramjet engines. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2011. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/ETD-UT-2011-05-3203.

Council of Science Editors:

Koo H. Large-eddy simulations of scramjet engines. [Doctoral Dissertation]. University of Texas – Austin; 2011. Available from: http://hdl.handle.net/2152/ETD-UT-2011-05-3203

University of Texas – Austin

16. Alayavalli, Kaushik Comandoor. Design, fabrication and testing of graphite bipolar plates for direct methanol fuel cells by indirect laser sintering.

Degree: PhD, Materials Science and Engineering, 2011, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2011-08-3894

► Direct Methanol Fuel Cells (DMFCs) are electrochemical energy conversion devices that convert chemical energy into electrical energy. The bipolar plate component of the DMFC is… (more)

▼ Direct Methanol Fuel Cells (DMFCs) are electrochemical energy conversion devices that convert chemical energy into electrical energy. The bipolar plate component of the DMFC is required to be fluid impermeable to prevent fuel leakage and electrically conductive to collect the electrons produced within the cell. Graphite possesses the properties of high electrical conductivity, low weight and resistance to corrosion that make it an attractive material for bipolar plates. However, the poor mechanical properties of graphite lead to prohibitive machining costs and increased production times. The objective of this research is to develop an indirect laser sintering (LS) process, involving the laser sintering of graphite powders mixed with a phenolic resin binder which offers the advantage of complex part production and testing of prototype bipolar plates in short times. Due to the nature of the indirect LS process, the as-produced (green part) plates are porous and possess low electrical conductivities (< 0.1 S.cm-1). This research describes a viable method to rapidly fabricate and test multiple graphite bipolar plate designs using indirect LS. This process involved identifying and selecting suitable graphite powder and binder systems based on their thermal and electrical properties and developing a post process heat treatment method for achieving electrical conductivity of 250 S/cm for LS graphite parts which exceeds the DOE target of 100 S/cm for bipolar plate materials. The post processing also covered a method of infiltration using cyanoacrylate which was capable of rendering porous brown parts fluid impermeable and suitable for use in DMFCs. The cyanoacrylate infiltrated LS graphite parts were characterized for flexural strength and electrical and thermal conductivities and bipolar plates were made and evaluated in a DMFC test stand. Various flow field designs including plates with varying channel and rib widths and triangular, elliptical and rectangular flow field cross sections were fabricated using indirect LS and their respective polarization curves were compared to commercially machined graphite plates. The fuel cell tests show the improvement in mass transport performance could be due to improved methanol distribution and water removal characteristics of triangular and elliptical cross sectional channels over rectangular channels of equivalent dimensions. Advisors/Committee Members: Bourell, David Lee (advisor), Manthiram, Arumugam (committee member), Meyers, Jeremy (committee member), Juenger, Maria G. (committee member), Moser, Robert (committee member).

Subjects/Keywords: DMFC bipolar plate; Indirect laser sintering; Flow field design

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APA (6^th Edition):

Alayavalli, K. C. (2011). Design, fabrication and testing of graphite bipolar plates for direct methanol fuel cells by indirect laser sintering. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2011-08-3894

Chicago Manual of Style (16^th Edition):

Alayavalli, Kaushik Comandoor. “Design, fabrication and testing of graphite bipolar plates for direct methanol fuel cells by indirect laser sintering.” 2011. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/ETD-UT-2011-08-3894.

MLA Handbook (7^th Edition):

Alayavalli, Kaushik Comandoor. “Design, fabrication and testing of graphite bipolar plates for direct methanol fuel cells by indirect laser sintering.” 2011. Web. 24 Jan 2021.

Vancouver:

Alayavalli KC. Design, fabrication and testing of graphite bipolar plates for direct methanol fuel cells by indirect laser sintering. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2011. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/ETD-UT-2011-08-3894.

Council of Science Editors:

Alayavalli KC. Design, fabrication and testing of graphite bipolar plates for direct methanol fuel cells by indirect laser sintering. [Doctoral Dissertation]. University of Texas – Austin; 2011. Available from: http://hdl.handle.net/2152/ETD-UT-2011-08-3894

University of Texas – Austin

17. Graham, Lindley Christin. Adaptive measure-theoretic parameter estimation for coastal ocean modeling.

Degree: PhD, Computational science, engineering, and mathematics, 2015, University of Texas – Austin

URL: http://hdl.handle.net/2152/32435

► Since Hurricane Katrina (2005), there has been a marked increase in the quantity of field observations gathered during and after hurricanes. There has also been… (more)

▼ Since Hurricane Katrina (2005), there has been a marked increase in the quantity of field observations gathered during and after hurricanes. There has also been an increased effort to improve our ability to model hurricanes and other coastal ocean phenomena. The majority of death and destruction due to a hurricane is from storm surge. The primary controlling factor in storm surge is the balance between the surface stress due to the wind and bottom stress. Manning's formula can be used to model the bottom stress; the formula includes the Manning's n coefficient which accounts for momentum loss due to bottom roughness and is a spatially dependent field. It is impractical to measure Manning's n over large physical domains. Instead, given a computational storm surge model and a set of model observations, one may formulate and solve an inverse problem to determine probable Manning's n fields using observational data, which in turn can be used for predictive simulations. On land, Manning's n may be inferred from land cover classification maps. We leverage existing land cover classification data to determine the spatial distribution of land cover classifications which we consider certain. These classifications can be used to obtain a parameterized mesoscale representation of the Manning's n field. We seek to estimate the Manning's n coefficients for this parameterized field. The inverse problem we solve is formulated using a measure-theoretic approach; using the ADvanced CIRCulation model for coastal and estuarine waters as the forward model of storm surge. The uncertainty in observational data is described as a probability measure on the data space. The solution to the inverse problem is a non-parametric probability measure on the parameter space. The goal is to use this solution in order to measure the probability of arbitrary events in the parameter space. In the cases studied here the dimension of the data space is smaller than the dimension of the parameter space. Thus, the inverse of a fixed datum is generally a set of values in parameter space. The advantage of using the measure-theoretic approach is that it preserves the geometric relation between the data space and the parameter space within the probability measure. Solving an inverse problem often involves the exploration of a high-dimensional parameter space requiring numerous expensive forward model solves. We use adaptive algorithms for solving the stochastic inverse problem to reduce error in the estimated probability of implicitly defined parameter events while minimizing the number of forward model solves. Advisors/Committee Members: Dawson, Clinton N. (advisor), Butler, Troy (committee member), Gamba, Irene (committee member), Ghattas, Omar (committee member), Moser, Robert (committee member).

Subjects/Keywords: Manning’s n coefficient; Measure theory; Parameter estimation; Set-valued inverse solutions; Shallow water equations; Stochastic inverse problems

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APA (6^th Edition):

Graham, L. C. (2015). Adaptive measure-theoretic parameter estimation for coastal ocean modeling. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/32435

Chicago Manual of Style (16^th Edition):

Graham, Lindley Christin. “Adaptive measure-theoretic parameter estimation for coastal ocean modeling.” 2015. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/32435.

MLA Handbook (7^th Edition):

Graham, Lindley Christin. “Adaptive measure-theoretic parameter estimation for coastal ocean modeling.” 2015. Web. 24 Jan 2021.

Vancouver:

Graham LC. Adaptive measure-theoretic parameter estimation for coastal ocean modeling. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2015. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/32435.

Council of Science Editors:

Graham LC. Adaptive measure-theoretic parameter estimation for coastal ocean modeling. [Doctoral Dissertation]. University of Texas – Austin; 2015. Available from: http://hdl.handle.net/2152/32435

University of Texas – Austin

18. Trembacki, Bradley Louis. Electrochemical transport simulation of 3D lithium-ion battery electrode microstructures.

Degree: PhD, Mechanical Engineering, 2015, University of Texas – Austin

URL: http://hdl.handle.net/2152/63883

► Lithium-ion batteries are commonly modeled using a volume-averaged formulation (porous electrode theory) in order to simulate battery behavior on a large scale. These methods utilize… (more)

▼ Lithium-ion batteries are commonly modeled using a volume-averaged formulation (porous electrode theory) in order to simulate battery behavior on a large scale. These methods utilize effective material properties and assume a simplified spherical geometry of the electrode particles. In contrast, a particle-scale (non-porous electrode) simulation applied to resolved electrode geometries predicts localized phenomena. Complete simulations of batteries require a coupling of the two scales to resolve the relevant physics. A central focus of this thesis is to develop a fully-coupled finite volume methodology for the simulation of the electrochemical equations in a lithium-ion battery cell at both the particle scale and using volume-averaged formulations. Due to highly complex electrode geometries at the particle scale, the formulation employs an unstructured computational mesh and is implemented within the MEMOSA software framework of Purdue’s PRISM (Prediction of Reliability, Integrity and Survivability of Microsystems) center. Stable and efficient algorithms are developed for full coupling of the nonlinear species transport equations, electrostatics, and Butler-Volmer kinetics. The model is applied to synthetic electrode particle beds for comparison with porous electrode theory simulations and to evaluate numerical performance capabilities. The model is also applied to a half-cell mesh created from a real cathode particle bed reconstruction to demonstrate the feasibility of such simulations. The second focus of the thesis is to investigate 3D battery electrode architectures that offer potential energy density and power density improvements over traditional particle bed battery geometries. A singular feature of these geometries is their interpenetrating nature, which significantly reduces diffusion distance. Advancement of micro-scale additive manufacturing techniques has made it possible to fabricate these electrode microarchitectures. A fully-coupled finite volume methodology for the transport equations coupled to the relevant electrochemistry is implemented in the PETSc (Portable, Extensible Toolkit for Scientific Computation) software framework which allows for a straightforward scalable simulation on orthogonal hexahedral meshes. Such scalability becomes important when performing simulations on fully resolved microstructures with many parameter sweeps across multiple variables. Using the computational model, a variety of 3D battery electrode geometries are simulated and compared across various battery discharge rates and length scales in order to quantify performance trends and investigate geometrical factors that improve battery performance. The energy density and power density of the 3D battery microstructures are compared in several ways, including a uniform surface area to volume ratio comparison as well as a comparison requiring a minimum manufacturable feature size. Significant performance improvements over traditional particle bed electrode designs are observed, and electrode microarchitectures… Advisors/Committee Members: Murthy, Jayathi (advisor), Moser, Robert D (committee member), Roberts, Scott A (committee member), Duoss, Eric B (committee member), Chen, Dongmei (committee member).

Subjects/Keywords: Battery; Simulation; Lithium-ion; Microstructure; Transport; Finite volume; Interpenetrating; Particle-scale; Volume-averaged; PETSc

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APA (6^th Edition):

Trembacki, B. L. (2015). Electrochemical transport simulation of 3D lithium-ion battery electrode microstructures. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/63883

Chicago Manual of Style (16^th Edition):

Trembacki, Bradley Louis. “Electrochemical transport simulation of 3D lithium-ion battery electrode microstructures.” 2015. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/63883.

MLA Handbook (7^th Edition):

Trembacki, Bradley Louis. “Electrochemical transport simulation of 3D lithium-ion battery electrode microstructures.” 2015. Web. 24 Jan 2021.

Vancouver:

Trembacki BL. Electrochemical transport simulation of 3D lithium-ion battery electrode microstructures. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2015. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/63883.

Council of Science Editors:

Trembacki BL. Electrochemical transport simulation of 3D lithium-ion battery electrode microstructures. [Doctoral Dissertation]. University of Texas – Austin; 2015. Available from: http://hdl.handle.net/2152/63883

University of Texas – Austin

19. -9901-8670. Development and evaluation of an advanced microwave radiance data assimilation system for estimating snow water storage at the continental scale.

Degree: PhD, Geological Sciences, 2016, University of Texas – Austin

URL: http://hdl.handle.net/2152/45944

► Snow cover modulates the Earth's surface energy and water fluxes, and snowmelt runoff is the principal source of water for humans and ecosystems in many… (more)

▼ Snow cover modulates the Earth's surface energy and water fluxes, and snowmelt runoff is the principal source of water for humans and ecosystems in many of the middle to high latitudes in the Northern Hemisphere. Understanding spatial and temporal variation in snowpack is crucial for climate studies and water resource management and thus the climate and hydrological research communities have invested in improving large-scale snow estimates. This dissertation aims to develop an advanced snow radiance assimilation (RA) system to improve continental-scale snow water storage estimates. The RA system is comprised of the Community Land Model version 4 (CLM4) (for snow energy and mass balance modeling), radiative transfer models (RTMs) (for brightness temperature estimates), and the Data Assimilation Research Testbed (DART) (for ensemble-based data assimilation). Two snowpack RTMs, the Microwave Emission Model for Layered Snowpacks (MEMLS) and the Dense Media Radiative Transfer – Multi Layers model (DMRT-ML), are used to simulate T[subscript B] of a multi-layered snowpack. Through an error characterization study, this dissertation presents that the correlations between snow water equivalent (SWE) error and brightness temperature (T[subscript B]) error and subsequent RA performance in estimating snow are significantly affected by all physical properties of soil and snow involved in estimating T[subscript B]. Based on the error characterization results, it is hypothesized that the continental-scale RA performance in estimating snow water storage can be improved by simultaneously updating all model physical states and parameters determining T[subscript B] based on a rule, in which prior estimates are updated depending on their correlations with a prior T[subscript B]. The results of a series of RA experiments show that the improved continental-scale snow estimates are obtained by applying the hypothesis. This dissertation also shows that further improvement of the performance of the RA system can be achieved, especially for vegetated areas, by assimilating the best-performing frequency channels (i.e., 18.7 and 23.8 GHz) and by considering the vegetation single scattering albedo to represent the vegetation effect on T[subscript B] at the top of the atmosphere. Advisors/Committee Members: Yang, Zong-liang (advisor), Dickinson, Robert E. (committee member), Fu, Rong (committee member), Rodell, Matthew (committee member), Moser, Robert D. (committee member).

Subjects/Keywords: Microwave brightness temperature; Radiance assimilation; Continental scale; Snow radiance; Data assimilation; Snow water storage; Land-surface modeling; Snow hydrology

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APA (6^th Edition):

-9901-8670. (2016). Development and evaluation of an advanced microwave radiance data assimilation system for estimating snow water storage at the continental scale. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/45944

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Chicago Manual of Style (16^th Edition):

-9901-8670. “Development and evaluation of an advanced microwave radiance data assimilation system for estimating snow water storage at the continental scale.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/45944.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

MLA Handbook (7^th Edition):

-9901-8670. “Development and evaluation of an advanced microwave radiance data assimilation system for estimating snow water storage at the continental scale.” 2016. Web. 24 Jan 2021.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Vancouver:

-9901-8670. Development and evaluation of an advanced microwave radiance data assimilation system for estimating snow water storage at the continental scale. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/45944.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Council of Science Editors:

-9901-8670. Development and evaluation of an advanced microwave radiance data assimilation system for estimating snow water storage at the continental scale. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/45944

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

20. Jeon, Chan-Hoo. Modeling of debris flows and induced phenomena with non-Newtonian fluid models.

Degree: PhD, Civil Engineering, 2015, University of Texas – Austin

URL: http://hdl.handle.net/2152/32822

► Debris flows contain inhomogeneous distributions of solids within a liquid. By considering a mixture of solid and liquid forming debris flows as a non-Newtonian continuous… (more)

Subjects/Keywords: Debris flow; Non-Newtonian fluid; Modeling; Level set method

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APA (6^th Edition):

Jeon, C. (2015). Modeling of debris flows and induced phenomena with non-Newtonian fluid models. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/32822

Chicago Manual of Style (16^th Edition):

Jeon, Chan-Hoo. “Modeling of debris flows and induced phenomena with non-Newtonian fluid models.” 2015. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/32822.

MLA Handbook (7^th Edition):

Jeon, Chan-Hoo. “Modeling of debris flows and induced phenomena with non-Newtonian fluid models.” 2015. Web. 24 Jan 2021.

Vancouver:

Jeon C. Modeling of debris flows and induced phenomena with non-Newtonian fluid models. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2015. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/32822.

Council of Science Editors:

Jeon C. Modeling of debris flows and induced phenomena with non-Newtonian fluid models. [Doctoral Dissertation]. University of Texas – Austin; 2015. Available from: http://hdl.handle.net/2152/32822

University of Texas – Austin

21. -2456-1577. Anisotropic hybrid turbulence modeling with specific application to the simulation of pulse-actuated dynamic stall control.

Degree: PhD, Mechanical engineering, 2015, University of Texas – Austin

URL: http://hdl.handle.net/2152/33393

► Experimental studies have shown pulse actuated dynamic stall control may provide a simple means to significantly increase the performance of lifting surfaces and expand their… (more)

Subjects/Keywords: Turbulence; RANS; LES; Hybrid; V2f; Simulation; Anisotropic; Inhomogeneous; Resolution; SGS; Structure-function; Stall control

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APA (6^th Edition):

-2456-1577. (2015). Anisotropic hybrid turbulence modeling with specific application to the simulation of pulse-actuated dynamic stall control. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/33393

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Chicago Manual of Style (16^th Edition):

-2456-1577. “Anisotropic hybrid turbulence modeling with specific application to the simulation of pulse-actuated dynamic stall control.” 2015. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/33393.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

MLA Handbook (7^th Edition):

-2456-1577. “Anisotropic hybrid turbulence modeling with specific application to the simulation of pulse-actuated dynamic stall control.” 2015. Web. 24 Jan 2021.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Vancouver:

-2456-1577. Anisotropic hybrid turbulence modeling with specific application to the simulation of pulse-actuated dynamic stall control. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2015. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/33393.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Council of Science Editors:

-2456-1577. Anisotropic hybrid turbulence modeling with specific application to the simulation of pulse-actuated dynamic stall control. [Doctoral Dissertation]. University of Texas – Austin; 2015. Available from: http://hdl.handle.net/2152/33393

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

University of Texas – Austin

22. Brooke, Steven Thomas. The politics of Islamist social service provision in Egypt.

Degree: PhD, Government, 2015, University of Texas – Austin

URL: http://hdl.handle.net/2152/46775

► Since its re-emergence under Anwar El-Sadat in the 1970s, the Muslim Brotherhood has provided millions of Egyptians with a valuable array of social services, from… (more)

Subjects/Keywords: Egypt; Social service provision; Islamist groups; Democratization; Authoritarianism

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APA (6^th Edition):

Brooke, S. T. (2015). The politics of Islamist social service provision in Egypt. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/46775

Chicago Manual of Style (16^th Edition):

Brooke, Steven Thomas. “The politics of Islamist social service provision in Egypt.” 2015. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/46775.

MLA Handbook (7^th Edition):

Brooke, Steven Thomas. “The politics of Islamist social service provision in Egypt.” 2015. Web. 24 Jan 2021.

Vancouver:

Brooke ST. The politics of Islamist social service provision in Egypt. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2015. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/46775.

Council of Science Editors:

Brooke ST. The politics of Islamist social service provision in Egypt. [Doctoral Dissertation]. University of Texas – Austin; 2015. Available from: http://hdl.handle.net/2152/46775

23. Neupane, Prapti. Advances towards a multi-dimensional discontinuous Galerkin method for modeling hurricane storm surge induced flooding in coastal watersheds.

Degree: PhD, Computational and applied mathematics, 2016, University of Texas – Austin

URL: http://hdl.handle.net/2152/41984

► Coastal areas are regions of high population density and urbanization. These areas are highly vulnerable to inundation and flooding not only because of hurricane storm… (more)

▼ Coastal areas are regions of high population density and urbanization. These areas are highly vulnerable to inundation and flooding not only because of hurricane storm surge, but also because of the torrential rainfall that often accompanies hurricanes. In order to accurately predict the extent of damage such an event might cause, any model that is used to simulate this process needs to couple rainfall with storm surge. The works that have tried to address this issue have mostly used a unidirectional coupling technique, where one of the following two approaches is taken. In the first approach, a hydrology model is used in the domain of interest and storm surge is incorporated in the domain as a boundary condition. In the second approach, a storm surge model is used in the domain of interest and rainfall is incorporated in the domain as a river inflow boundary condition. Neither of these approaches allows the rainwater and the surge water to interact bidirectionally. In order to improve on those efforts, in this dissertation, we develop a comprehensive framework for modeling flooding in coastal watersheds. We present an approach to decompose a watershed into multiple sub-domains depending on the dynamics of flow in the region. We use different simplifications of the shallow water equations on different sub-domains to gain computational efficiency without compromising on physical accuracy. The different sub-domains are coupled with each other through numerical fluxes in a discontinuous Galerkin framework. This technique allows for a tight coupling of storm surge with rainfall runoff, so that the flooding that occurs is truly influenced by the nonlinear interaction of these two processes. We present numerical tests to validate and verify the methods used for modeling flow in different sub-domains as well as the techniques used for coupling different sub-domains with each other. Advisors/Committee Members: Dawson, Clinton N. (advisor), Gamba, Irene M (committee member), Engquist, Bjorn (committee member), Bui-Thanh, Tan (committee member), Moser, Robert D (committee member).

Subjects/Keywords: Hurricane storm surge; Rainfall runoff; Flooding; Discontinuous Galerkin method; Computational hydrology; Multi-dimensional model; Shallow water equations

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APA (6^th Edition):

Neupane, P. (2016). Advances towards a multi-dimensional discontinuous Galerkin method for modeling hurricane storm surge induced flooding in coastal watersheds. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/41984

Chicago Manual of Style (16^th Edition):

Neupane, Prapti. “Advances towards a multi-dimensional discontinuous Galerkin method for modeling hurricane storm surge induced flooding in coastal watersheds.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/41984.

MLA Handbook (7^th Edition):

Neupane, Prapti. “Advances towards a multi-dimensional discontinuous Galerkin method for modeling hurricane storm surge induced flooding in coastal watersheds.” 2016. Web. 24 Jan 2021.

Vancouver:

Neupane P. Advances towards a multi-dimensional discontinuous Galerkin method for modeling hurricane storm surge induced flooding in coastal watersheds. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/41984.

Council of Science Editors:

Neupane P. Advances towards a multi-dimensional discontinuous Galerkin method for modeling hurricane storm surge induced flooding in coastal watersheds. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/41984

University of Texas – Austin

24. Zhou, Jun, Ph. D. Modeling and simulation of thermal ablation in vascularized tissues.

Degree: PhD, Mechanical engineering, 2015, University of Texas – Austin

URL: http://hdl.handle.net/2152/31552

► Thermal ablation, which uses localized heating by external energy sour-ces to destroy abnormal tissues, has been increasingly used as a treatment modality for cancers. Its… (more)

▼ Thermal ablation, which uses localized heating by external energy sour-ces to destroy abnormal tissues, has been increasingly used as a treatment modality for cancers. Its efficacy hinges on the ability to control temperature and induce sufficient thermal damage in the targeted tissue regions. However, it is difficult for clinicians to decide what treatment settings should be applied to obtain the best treatment outcome while minimizing adverse effects. Help from numerical simulations in the treatment planning process would therefore be highly valuable, if the predictions are realistic, reliable and accurate. The complexity of tissue structures and the coupling of heat transfer with other biophysical phenomena such as blood perfusion, tissue damage and thermoregulation make it a challenge to predict temperature fields and thermal damage in living tissues. Approximate models with uncertain parameters are then used in the simulations. The important question is, which features are necessary to include in a model for plausible predictions to guide clinical treatment? Furthermore, what can be done to improve prediction accuracy? To address these issues a series of numerical simulations of radiofrequency (RF) ablation were performed that include the following effects: 1) the thermal effects of micro vascular perfusion, 2) the impact of tissue damage on that perfusion, and 3) the thermal effects of discrete blood vessels. In addition two distinct models of the thermal effects of perfusion, with very different underlying assumptions were used: Penne's bioheat transfer model, and a porous media model. The former is expected to be valid at large scales (e.g.,~the scale of a whole organ), while the latter is expected to be valid at small scales (e.g.,~the scale of a capillary bed). It is not clear what perfusion model is most appropriate at the intermediate scale of thermal ablation. The results of these simulations were analyzed to identify the most important factors to consider in treatment planning for RF ablation. By far the most important uncertainty in predicting the tissue damaged by RF ablation therapy was due to the difference between the two ablation models studied, resulting in a factor of two difference in the predicted volume of damaged tissue. Also important were the effective porosity of the tissue and the perfusion rate, especially in the case of the Pennes' perfusion model, and the presence of blood vessels larger than 0.5 mm in diameter and closer than 20 mm from the applicator. Of particular interest is the finding that it is very difficult to damage all tissue very close to a blood vessel larger than 3 mm in diameter, because of the cooling it provides. These observations suggest improved perfusion modeling, reliable determination of effective porosity and perfusion rate, and the mapping of large vessels in the treatment area would all improve the ability to predict the response to RF thermal ablation for treatment planning. Advisors/Committee Members: Moser, Robert deLancey (advisor), Feng, Yusheng (advisor), Biros, George (committee member), Diller, Kenneth R (committee member), Li, Wei (committee member).

Subjects/Keywords: Thermal ablation; Vascularized tissue; Modeling; Simulation

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APA (6^th Edition):

Zhou, Jun, P. D. (2015). Modeling and simulation of thermal ablation in vascularized tissues. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/31552

Chicago Manual of Style (16^th Edition):

Zhou, Jun, Ph D. “Modeling and simulation of thermal ablation in vascularized tissues.” 2015. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/31552.

MLA Handbook (7^th Edition):

Zhou, Jun, Ph D. “Modeling and simulation of thermal ablation in vascularized tissues.” 2015. Web. 24 Jan 2021.

Vancouver:

Zhou, Jun PD. Modeling and simulation of thermal ablation in vascularized tissues. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2015. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/31552.

Council of Science Editors:

Zhou, Jun PD. Modeling and simulation of thermal ablation in vascularized tissues. [Doctoral Dissertation]. University of Texas – Austin; 2015. Available from: http://hdl.handle.net/2152/31552

University of Texas – Austin

25. Arkilic, Zekiye Ayca. Between the homeland and host states : Turkey’s diaspora policies and immigrant political participation in France and Germany.

Degree: PhD, Government, 2016, University of Texas – Austin

URL: http://hdl.handle.net/2152/61482

► This dissertation analyzes why sending states develop specific diaspora outreach policies and how those policies affect the political participation of immigrant organization leaders in host… (more)

▼ This dissertation analyzes why sending states develop specific diaspora outreach policies and how those policies affect the political participation of immigrant organization leaders in host countries. I theorize and empirically test the propositions that diaspora outreach policies are a growing and significant preoccupation of sending states and that they play a pivotal role in motivating immigrant leaders to participate in host state politics. I argue that sending states influence immigrant political participation through the “diaspora empowerment” mechanism, which reshapes immigrant organizations leaders’ identification and capabilities. More specifically, sending states instill a sense of self-efficacy, collective identity, and group consciousness in the leaders of immigrant organizations and provide them with technical, financial, and legal support. I test my hypotheses through an extensive analysis of Turkey’s relations with expatriate umbrella organizations operating in France and Germany, two countries that are the leading recipients of Turkish immigrants in Western Europe. My analysis shows that origin states may apply a multi-tiered diaspora policy based on the size and the loyalty of immigrant organizations. This differential treatment affects the frequency and form of immigrant political activism oriented toward host states. I conclude that the leaders of immigrant organizations are more likely to be receptive to the sending state’s diaspora policies if they hold strong grievances toward their host state. Greater grievances lead to greater receptivity because they encourage immigrant leaders to identify with the sending state rather than the host state. My findings draw from secondary literature, content analysis of organizational and governmental reports, semi-structured in-depth interviews, participant observation, and survey research. Advisors/Committee Members: Freeman, Gary P. (advisor), Givens, Terri E., 1964- (advisor), Moser, Robert G. (committee member), Madrid, Raul L. (committee member), Tepe, Sultan (committee member).

Subjects/Keywords: Diaspora policies; Turkey; Immigrant integration; France; Germany

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APA (6^th Edition):

Arkilic, Z. A. (2016). Between the homeland and host states : Turkey’s diaspora policies and immigrant political participation in France and Germany. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/61482

Chicago Manual of Style (16^th Edition):

Arkilic, Zekiye Ayca. “Between the homeland and host states : Turkey’s diaspora policies and immigrant political participation in France and Germany.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/61482.

MLA Handbook (7^th Edition):

Arkilic, Zekiye Ayca. “Between the homeland and host states : Turkey’s diaspora policies and immigrant political participation in France and Germany.” 2016. Web. 24 Jan 2021.

Vancouver:

Arkilic ZA. Between the homeland and host states : Turkey’s diaspora policies and immigrant political participation in France and Germany. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/61482.

Council of Science Editors:

Arkilic ZA. Between the homeland and host states : Turkey’s diaspora policies and immigrant political participation in France and Germany. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/61482

University of Texas – Austin

26. Dennis, Michael Patrick. Attitudes in transition : Chechen refugees and the politics of violence: Chechen refugees and the politics of violence.

Degree: PhD, Government, 2011, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2011-12-4703

► What drives refugees displaced by war to hold attitudes supporting violence to achieve political ends? The conventional wisdom suggests that refugee communities are breeding grounds… (more)

▼ What drives refugees displaced by war to hold attitudes supporting violence to achieve political ends? The conventional wisdom suggests that refugee communities are breeding grounds for the emergence of political violence, terrorism, and radicalism. Yet, the literature on refugees and political violence offers little empirical evidence of such a connection or systematic investigation of the root causes of attitudes toward political violence among refugees. My research addresses the following questions: 1) What are the sources of politically violent attitudes? 2) Can these sources be traced to specific aspects of the refugee communities themselves? 3) Can they be traced to certain experiential events or demographic factors? 4) Are attitudes towards political violence related to actors’ political goals? This analysis is based on nearly three years of fieldwork in Chechen refugee communities in The Republic of Georgia, Azerbaijan, Poland, and Belgium. Methodologically, this inductive study employed a mixed-methods approach, utilizing qualitative and ethnographic methods, such as direct participant-observer, to conduct 310 structured-interviews with a range of Chechen refugees. For independent variables I asked a battery of questions related to demographic profiles, grievances, political goals and preferences, and preferences for regime type. The dependent variable, attitudes towards political violence, was gleaned from structured-interviews which called on subjects to offer general assessments of their position on the acceptability of political violence as well as express their views on the legitimacy of four concrete events related to the conflict in Chechnya: the 2002 attack on Moscow’s Dubrovka Theater; the 2004 attack on School1 in Beslan, North Ossetia; the 2004 attack on military and police personnel in Nazran, Ingushetia; and the 2005 attack on military and police personnel in Nalchik, Kabardino-Balkaria. Advisors/Committee Members: Moser, Robert G., 1966- (advisor), Barany, Zoltan (committee member), Pedahzur, Ami (committee member), Wagner, R. Harrison (committee member), Garza, Thomas (committee member).

Subjects/Keywords: Chechen refugees; Political violence

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APA (6^th Edition):

Dennis, M. P. (2011). Attitudes in transition : Chechen refugees and the politics of violence: Chechen refugees and the politics of violence. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2011-12-4703

Chicago Manual of Style (16^th Edition):

Dennis, Michael Patrick. “Attitudes in transition : Chechen refugees and the politics of violence: Chechen refugees and the politics of violence.” 2011. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/ETD-UT-2011-12-4703.

MLA Handbook (7^th Edition):

Dennis, Michael Patrick. “Attitudes in transition : Chechen refugees and the politics of violence: Chechen refugees and the politics of violence.” 2011. Web. 24 Jan 2021.

Vancouver:

Dennis MP. Attitudes in transition : Chechen refugees and the politics of violence: Chechen refugees and the politics of violence. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2011. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/ETD-UT-2011-12-4703.

Council of Science Editors:

Dennis MP. Attitudes in transition : Chechen refugees and the politics of violence: Chechen refugees and the politics of violence. [Doctoral Dissertation]. University of Texas – Austin; 2011. Available from: http://hdl.handle.net/2152/ETD-UT-2011-12-4703

27. Malaya, Nicholas Penha. Numerical simulation of synthetic, buoyancy-induced columnar vortices.

Degree: PhD, Mechanical engineering, 2016, University of Texas – Austin

URL: http://hdl.handle.net/2152/45689

► Much of the solar energy incident on the Earth’s surface is absorbed into the ground, which in turn heats the air layer above the surface.… (more)

Subjects/Keywords: CFD; Scientific computing; Optimization; Dust devils

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APA (6^th Edition):

Malaya, N. P. (2016). Numerical simulation of synthetic, buoyancy-induced columnar vortices. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/45689

Chicago Manual of Style (16^th Edition):

Malaya, Nicholas Penha. “Numerical simulation of synthetic, buoyancy-induced columnar vortices.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/45689.

MLA Handbook (7^th Edition):

Malaya, Nicholas Penha. “Numerical simulation of synthetic, buoyancy-induced columnar vortices.” 2016. Web. 24 Jan 2021.

Vancouver:

Malaya NP. Numerical simulation of synthetic, buoyancy-induced columnar vortices. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/45689.

Council of Science Editors:

Malaya NP. Numerical simulation of synthetic, buoyancy-induced columnar vortices. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/45689

University of Texas – Austin

28. Evans, John Andrews. Divergence-free B-spline discretizations for viscous incompressible flows.

Degree: PhD, Computational and Applied Mathematics, 2011, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2011-12-4506

► The incompressible Navier-Stokes equations are among the most important partial differential systems arising from classical physics. They are utilized to model a wide range of… (more)

▼ The incompressible Navier-Stokes equations are among the most important partial differential systems arising from classical physics. They are utilized to model a wide range of fluids, from water moving around a naval vessel to blood flowing through the arteries of the cardiovascular system. Furthermore, the secrets of turbulence are widely believed to be locked within the Navier-Stokes equations. Despite the enormous applicability of the Navier-Stokes equations, the underlying behavior of solutions to the partial differential system remains little understood. Indeed, one of the Clay Mathematics Institute's famed Millenium Prize Problems involves the establishment of existence and smoothness results for Navier-Stokes solutions, and turbulence is considered, in the words of famous physicist Richard Feynman, to be "the last great unsolved problem of classical physics." Numerical simulation has proven to be a very useful tool in the analysis of the Navier-Stokes equations. Simulation of incompressible flows now plays a major role in the industrial design of automobiles and naval ships, and simulation has even been utilized to study the Navier-Stokes existence and smoothness problem. In spite of these successes, state-of-the-art incompressible flow solvers are not without their drawbacks. For example, standard turbulence models which rely on the existence of an energy spectrum often fail in non-trivial settings such as rotating flows. More concerning is the fact that most numerical methods do not respect the fundamental geometric properties of the Navier-Stokes equations. These methods only satisfy the incompressibility constraint in an approximate sense. While this may seem practically harmless, conservative semi-discretizations are typically guaranteed to balance energy if and only if incompressibility is satisfied pointwise. This is especially alarming as both momentum conservation and energy balance play a critical role in flow structure development. Moreover, energy balance is inherently linked to the numerical stability of a method. In this dissertation, novel B-spline discretizations for the generalized Stokes and Navier-Stokes equations are developed. The cornerstone of this development is the construction of smooth generalizations of Raviart-Thomas-Nedelec elements based on the new theory of isogeometric discrete differential forms. The discretizations are (at least) patch-wise continuous and hence can be directly utilized in the Galerkin solution of viscous flows for single-patch configurations. When applied to incompressible flows, the discretizations produce pointwise divergence-free velocity fields. This results in methods which properly balance both momentum and energy at the semi-discrete level. In the presence of multi-patch geometries or no-slip walls, the discontinuous Galerkin framework can be invoked to enforce tangential continuity without upsetting the conservation and stability properties of the method across patch boundaries. This also allows our method to default to a… Advisors/Committee Members: Hughes, Thomas J. R. (advisor), Babuska, Ivo (committee member), Demkowicz, Leszek (committee member), Ghattas, Omar (committee member), Moser, Robert D. (committee member), Bazilevs, Yuri (committee member).

Subjects/Keywords: Incompressible Navier-Stokes equations; B-splines; Mixed discretizations

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APA (6^th Edition):

Evans, J. A. (2011). Divergence-free B-spline discretizations for viscous incompressible flows. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2011-12-4506

Chicago Manual of Style (16^th Edition):

Evans, John Andrews. “Divergence-free B-spline discretizations for viscous incompressible flows.” 2011. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/ETD-UT-2011-12-4506.

MLA Handbook (7^th Edition):

Evans, John Andrews. “Divergence-free B-spline discretizations for viscous incompressible flows.” 2011. Web. 24 Jan 2021.

Vancouver:

Evans JA. Divergence-free B-spline discretizations for viscous incompressible flows. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2011. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/ETD-UT-2011-12-4506.

Council of Science Editors:

Evans JA. Divergence-free B-spline discretizations for viscous incompressible flows. [Doctoral Dissertation]. University of Texas – Austin; 2011. Available from: http://hdl.handle.net/2152/ETD-UT-2011-12-4506

University of Texas – Austin

29. Morrison, Rebecca Elizabeth. On the representation of model inadequacy : a stochastic operator approach.

Degree: PhD, Computational science, engineering, and mathematics, 2016, University of Texas – Austin

URL: http://hdl.handle.net/2152/40259

► Mathematical models of physical systems are subject to many sources of uncertainty such as measurement errors and uncertain initial and boundary conditions. After accounting for… (more)

▼ Mathematical models of physical systems are subject to many sources of uncertainty such as measurement errors and uncertain initial and boundary conditions. After accounting for these uncertainties, it is often revealed that there remains some discrepancy between the model output and the observations; if so, the model is said to be inadequate. In practice, the inadequate model may be the best that is available or tractable, and so despite its inadequacy the model may be used to make predictions of unobserved quantities. In this case, a representation of the inadequacy is necessary, so the impact of the observed discrepancy can be determined. We investigate this problem in the context of chemical kinetics and propose a new technique to account for model inadequacy that is both probabilistic and physically meaningful. Chemical reactions are generally modeled by a set of nonlinear ordinary differential equations (ODEs) for the concentrations of the species and temperature. In this work, a stochastic inadequacy operator S is introduced which includes three parts. The first is represented by a random matrix which is embedded within the ODEs of the concentrations. The matrix is required to satisfy several physical constraints, and its most general form exhibits some useful properties, such as having only non-positive eigenvalues. The second is a smaller but specific set of nonlinear terms that also modifies the species’ concentrations, and the third is an operator that properly accounts for changes to the energy equation due to the previous changes. The entries of S are governed by probability distributions, which in turn are characterized by a set of hyperparameters. The model parameters and hyperparameters are calibrated using high-dimensional hierarchical Bayesian inference, with data from a range of initial conditions. This allows the use of the inadequacy operator on a wide range of scenarios, rather than correcting any particular realization of the model with a corresponding data set. We apply the method to typical problems in chemical kinetics including the reaction mechanisms of hydrogen and methane combustion. We also study how the inadequacy representation affects an unobserved quantity of interest— the flamespeed of a one-dimensional hydrogen laminar flame. Advisors/Committee Members: Moser, Robert deLancey (advisor), Oden, John Tinsley (committee member), Ghattas, Omar (committee member), Henkelman, Graeme (committee member), Oliver, Todd A (committee member), Simmons, Christopher S (committee member).

Subjects/Keywords: Uncertainty quantification; Model inadequacy; Stochastic operator; Bayesian inference; Chemical kinetics

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APA (6^th Edition):

Morrison, R. E. (2016). On the representation of model inadequacy : a stochastic operator approach. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/40259

Chicago Manual of Style (16^th Edition):

Morrison, Rebecca Elizabeth. “On the representation of model inadequacy : a stochastic operator approach.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/40259.

MLA Handbook (7^th Edition):

Morrison, Rebecca Elizabeth. “On the representation of model inadequacy : a stochastic operator approach.” 2016. Web. 24 Jan 2021.

Vancouver:

Morrison RE. On the representation of model inadequacy : a stochastic operator approach. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/40259.

Council of Science Editors:

Morrison RE. On the representation of model inadequacy : a stochastic operator approach. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/40259

30. Voelkel, Stephen Joseph. Thermal nonequilibrium models for high-temperature reactive processes.

Degree: PhD, Computational Science, Engineering, and Mathematics, 2016, University of Texas – Austin

URL: http://hdl.handle.net/2152/47234

► This dissertation examines how thermal nonequilibrium affects mixing and combustion in high-enthalpy, high-speed systems such as reentry vehicles, scramjets, and detonation-driven engines. Specifically, the focus… (more)

▼ This dissertation examines how thermal nonequilibrium affects mixing and combustion in high-enthalpy, high-speed systems such as reentry vehicles, scramjets, and detonation-driven engines. Specifically, the focus is in the development of physical models that accurately describe thermal nonequilibrium in a continuum-scale ow and its relative effect on mixing and reaction processes. To this end, the quasi-classical trajectory method is utilized, in which bimolecular collisions (or trajectories) are individually simulated. The aggregate of the outcomes from many trajectories is then used to calculate the macroscopic reaction and scattering rates of the system. A QCT program is presented for massively parallel simulations, which includes an algorithm for calculating and tabulating the potential energy surface throughout the QCT simulation. Using the QCT program, chain-reactions in hydrogen combustions are simulated, and the subsequent rates are used directly in CFD simulations as well as to develop vibrational nonequilibrium reaction rate models. Also, nitrogen dissociation is simulated to calculate the dissociation rate as a function of independent translational, rotational, and vibrational temperatures, thus extending the conventional two-temperature model. This simulation is made tractable via a new method for selectively sampling trajectories. Finally, the QCT program is utilized to calculate N₂-O₂ inelastic cross-sections. This work was motivated by CFD simulations of experimental observations which indicated that the conventional N₂-O₂ vibrational exchange rates were invalid at moderate temperatures. The QCT-calculated rates support these observations. In addition to QCT-based simulations, 1D and 2D simulations of detonation waves with vibrational nonequilibrium (modeled using the aforementioned data) are analyzed. It is observed that nonequilibrium only marginally affects the induction zone of the detonation wave. However, in the 2D simulations, it is observed that vibrational nonequilibrium plays a critical role in determining detonation cell sizes. In summary, vibrational nonequilibrium is analyzed using QCT for a variety of systems, and the resulting data is utilized to develop CFD-scale models. We have high confidence in the resulting models because they are derived from first principles and microscopic observations as opposed to simplified models or empirical fits. Advisors/Committee Members: Varghese, Philip L. (advisor), Raman, Venkat (advisor), Arbogast, Todd J (committee member), Dawson, Clint N (committee member), Moser, Robert D (committee member), Stanton, John F (committee member).

Subjects/Keywords: Thermal nonequilibrium; Scramjet; Reentry vehicle; Quasi-classical trajectory; QCT; Hydrogen combustion; Nitrogen dissociation; Nitrogen-oxygen scattering

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APA (6^th Edition):

Voelkel, S. J. (2016). Thermal nonequilibrium models for high-temperature reactive processes. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/47234

Chicago Manual of Style (16^th Edition):

Voelkel, Stephen Joseph. “Thermal nonequilibrium models for high-temperature reactive processes.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/47234.

MLA Handbook (7^th Edition):

Voelkel, Stephen Joseph. “Thermal nonequilibrium models for high-temperature reactive processes.” 2016. Web. 24 Jan 2021.

Vancouver:

Voelkel SJ. Thermal nonequilibrium models for high-temperature reactive processes. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/47234.

Council of Science Editors:

Voelkel SJ. Thermal nonequilibrium models for high-temperature reactive processes. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/47234

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