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University of Alberta
1.
Martinez, Roberto Carlos.
Study of Enhanced Deposition due to Magnetic Field Alignment
of Ellipsoid Particles Using Direct Numerical Simulations.
Degree: MS, Department of Mechanical Engineering, 2012, University of Alberta
URL: https://era.library.ualberta.ca/files/vx021g61s 
► A recent in vitro study demonstrated a non invasive method to enhance local deposition in a small airway by controlling the angular position of magnetic…
(more)
▼ A recent in vitro study demonstrated a non invasive
method to enhance local deposition in a small airway by controlling
the angular position of magnetic high aspect ratio particles. This
technique could mitigate the challenge of providing sufficient
therapeutic effects when using aerosolized chemotherapy techniques.
To highlight the potential of this new magnetic field alignment
approach the effect of increasing particle aspect ratio on the
deposition efficiency was studied using direct numerical
simulations. Simulations were done using an in house finite element
algorithm. A steady air flow, typical of tidal breathing, was
simulated through a three dimensional physiologically realistic
bifurcation representing a single symmetrical bifurcation between
generations 14 and 15 in the lung. For two different aspect ratios
the deposition efficiency was found for the case of an
unconstrained particle and magnetically aligned particle. Results
indicate that forcing local alignment of high aspect ratio
particles can increase local deposition considerably.
Subjects/Keywords: Aerosols; Numerical Method; Deposition; Targeting
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APA (6th Edition):
Martinez, R. C. (2012). Study of Enhanced Deposition due to Magnetic Field Alignment
of Ellipsoid Particles Using Direct Numerical Simulations. (Masters Thesis). University of Alberta. Retrieved from https://era.library.ualberta.ca/files/vx021g61s
Chicago Manual of Style (16th Edition):
Martinez, Roberto Carlos. “Study of Enhanced Deposition due to Magnetic Field Alignment
of Ellipsoid Particles Using Direct Numerical Simulations.” 2012. Masters Thesis, University of Alberta. Accessed April 12, 2021.
https://era.library.ualberta.ca/files/vx021g61s.
MLA Handbook (7th Edition):
Martinez, Roberto Carlos. “Study of Enhanced Deposition due to Magnetic Field Alignment
of Ellipsoid Particles Using Direct Numerical Simulations.” 2012. Web. 12 Apr 2021.
Vancouver:
Martinez RC. Study of Enhanced Deposition due to Magnetic Field Alignment
of Ellipsoid Particles Using Direct Numerical Simulations. [Internet] [Masters thesis]. University of Alberta; 2012. [cited 2021 Apr 12].
Available from: https://era.library.ualberta.ca/files/vx021g61s.
Council of Science Editors:
Martinez RC. Study of Enhanced Deposition due to Magnetic Field Alignment
of Ellipsoid Particles Using Direct Numerical Simulations. [Masters Thesis]. University of Alberta; 2012. Available from: https://era.library.ualberta.ca/files/vx021g61s
Texas A&M University
2.
Leung, Wing Tat.
Adaptivity and Online Basis Construction for Generalized Multiscale Finite Element Methods.
Degree: PhD, Mathematics, 2017, Texas A&M University
URL: http://hdl.handle.net/1969.1/165860
► Many problems in application involve media with multiple scale, for example, in composite materials, porous media. These problems are usually computationally challenging since fine grid…
(more)
▼ Many problems in application involve media with multiple scale, for example, in composite materials, porous media. These problems are usually computationally challenging since fine grid computation is extremely expensive. Therefore, one may need to develop a coarse grid model reduction for this type of problems. In this dissertation, we will consider a multiscale
method called generalized multiscale finite element
method (GMsFEM).
GMsFEM follows the framework of multiscale finite element
method. Instead of using one basis function per coarse grid node, GMsFEM uses several basis functions for one coarse grid node. Since the media is highly heterogeneous and may involves high contrast, having more than one basis function per node is important to reduce the error significantly. Due to the varying heterogeneity in the domain, we may require different numbers of basis functions in different regions. Then the question is how to determine the number of basis functions in each region. In this dissertation, we will discuss an adaptive enrichment algorithm for enriching basis functions for the regions with large error. We will consider two different types of basis function for enrichment. One is using the pre-computed offline basis functions. We call this
method offline adaptive enrichment. The other
method uses online constructed basis functions called online adaptive enrichment.
In applications, non-conforming basis functions can give us more flexibility on gridding. The discontinuous Galerkin
method also makes the mass matrix block diagonal, which enhances the computation speed in solving time-dependent problem with an explicit scheme. In this dissertation, we will discuss offline and online adaptive methods for the generalized multiscale discontinuous Galerkin
method (GMsDGM). We will also discuss using GMsDGM for simulating wave propagation in heterogeneous media.
Advisors/Committee Members: Efendeiv, Yalchin (advisor), Chung, Eric (advisor), Gildin, Eduardo (committee member), Howard, Peter (committee member), Lazarov, Raytcho (committee member).
Subjects/Keywords: Multiscale Method; Numerical Analysis
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APA (6th Edition):
Leung, W. T. (2017). Adaptivity and Online Basis Construction for Generalized Multiscale Finite Element Methods. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/165860
Chicago Manual of Style (16th Edition):
Leung, Wing Tat. “Adaptivity and Online Basis Construction for Generalized Multiscale Finite Element Methods.” 2017. Doctoral Dissertation, Texas A&M University. Accessed April 12, 2021.
http://hdl.handle.net/1969.1/165860.
MLA Handbook (7th Edition):
Leung, Wing Tat. “Adaptivity and Online Basis Construction for Generalized Multiscale Finite Element Methods.” 2017. Web. 12 Apr 2021.
Vancouver:
Leung WT. Adaptivity and Online Basis Construction for Generalized Multiscale Finite Element Methods. [Internet] [Doctoral dissertation]. Texas A&M University; 2017. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/1969.1/165860.
Council of Science Editors:
Leung WT. Adaptivity and Online Basis Construction for Generalized Multiscale Finite Element Methods. [Doctoral Dissertation]. Texas A&M University; 2017. Available from: http://hdl.handle.net/1969.1/165860
University of Texas – Austin
3.
Nguyen, Hieu Huu.
Parallel-in-time methods for wave propagation in heterogeneous media.
Degree: PhD, Computational Science, Engineering, and Mathematics, 2020, University of Texas – Austin
URL: http://dx.doi.org/10.26153/tsw/10151
► Wave propagation is ubiquitous in science and engineering applications, but solving the second-order wave equation in a parallel way is still computationally challenging. Specifically, as…
(more)
▼ Wave propagation is ubiquitous in science and engineering applications, but solving the second-order wave equation in a parallel way is still computationally challenging. Specifically, as efficiency gained from spatial domain decomposition is saturated, time-domain becomes the next candidate for parallelization. However, most parallel-in-time methods are not effective in solving hyperbolic problems, including the wave equation. Motivated by the simple parareal algorithm developed by Lion, Maday, and Turinici, we propose a new parallel scheme called [theta]-parareal that generalizes the original parareal. The convergence and stability analysis of the [theta]-parareal scheme reveal the deficiency of the parareal
method when applying to highly oscillatory problems. We then develop a new parallel-in-time iterative
method for solving the homogeneous second-order wave equation. The new approach is a data-driven strategy in which we use pre-computed data to stabilize the iteration by minimizing the wave energy residual. We propose two techniques, a linear algebra-based
method, and a deep neural network
method.
Numerical examples, including a wave speed with discontinuities, are provided to demonstrate the effectiveness of the proposed methods on the wave equation.
Advisors/Committee Members: Tsai, Yen-Hsi R. (advisor), Bui-Thanh, Tan (committee member), Engquist, Bjorn (committee member), Ghattas, Omar (committee member), Ren, Kui (committee member).
Subjects/Keywords: Numerical method; Wave propagation
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APA (6th Edition):
Nguyen, H. H. (2020). Parallel-in-time methods for wave propagation in heterogeneous media. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://dx.doi.org/10.26153/tsw/10151
Chicago Manual of Style (16th Edition):
Nguyen, Hieu Huu. “Parallel-in-time methods for wave propagation in heterogeneous media.” 2020. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021.
http://dx.doi.org/10.26153/tsw/10151.
MLA Handbook (7th Edition):
Nguyen, Hieu Huu. “Parallel-in-time methods for wave propagation in heterogeneous media.” 2020. Web. 12 Apr 2021.
Vancouver:
Nguyen HH. Parallel-in-time methods for wave propagation in heterogeneous media. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2020. [cited 2021 Apr 12].
Available from: http://dx.doi.org/10.26153/tsw/10151.
Council of Science Editors:
Nguyen HH. Parallel-in-time methods for wave propagation in heterogeneous media. [Doctoral Dissertation]. University of Texas – Austin; 2020. Available from: http://dx.doi.org/10.26153/tsw/10151
University of New South Wales
4.
Zhang, Junqi.
Integrating geometric modeling and structure analysis: towards the digital future of engineering.
Degree: Civil & Environmental Engineering, 2019, University of New South Wales
URL: http://handle.unsw.edu.au/1959.4/63252
;
https://unsworks.unsw.edu.au/fapi/datastream/unsworks:60027/SOURCE02?view=true
► Numerical method has revolutionized the engineering. With the rapid development of modern computers, the numerical method will play a more important role in the future…
(more)
▼ Numerical method has revolutionized the engineering. With the rapid development of modern computers, the
numerical method will play a more important role in the future of engineering. However, a large amount of human effort is still required in an analysis to convert a geometric model to a
numerical model which can be accepted by computers. This manual process is time consuming and error prone, especially in an adaptive analysis where the mesh needs to be updated frequently. Additional challenges are imposed by new data formats used in industry, such as stereolithography (STL) models, virtual reality (VRML) models and digital image.In this thesis, a
numerical framework is developed to link geometric modeling and structure analysis automatically based on the scaled boundary finite element
method, which is capable of modeling polyhedrons with arbitrary number of faces and edges by discretizing their boundaries only. This framework accepts multiple data formats as input. High quality polyhedron meshes can be generated using octree algorithm with minimum human interventions. The meshes for different parts of a model can be generated independently and merged automatically by modifying the surface meshes on their interfaces only. No interface constraints or special shape functions are required in the analysis. Composite materials with inclusions such as fibers and anchors can also be modeled. Adaptive mesh refinement can be implemented based on a posterior error estimation. The meshes can be modified locally due to the advantage of the polyhedron elements.A virtual city analysis is performed using this framework, where a
numerical model of a city block is constructed to simulate the ground settlement, the air flow between buildings and the effect of earthquakes. Large scale modeling and analysis are possible because of the automation and efficiency of the proposed
method. The meshes generated for individual buildings, underground structures and terrain in the virtual city are reusable.The
numerical framework proposed in this thesis has been successfully applied by other researchers in acoustic, contact mechanics, fluid-structure interaction and many others.
Advisors/Committee Members: Song, Chongmin, Civil & Environmental Engineering, Faculty of Engineering, UNSW.
Subjects/Keywords: Meshes; Numerical method; Geometric model
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APA (6th Edition):
Zhang, J. (2019). Integrating geometric modeling and structure analysis: towards the digital future of engineering. (Doctoral Dissertation). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/63252 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:60027/SOURCE02?view=true
Chicago Manual of Style (16th Edition):
Zhang, Junqi. “Integrating geometric modeling and structure analysis: towards the digital future of engineering.” 2019. Doctoral Dissertation, University of New South Wales. Accessed April 12, 2021.
http://handle.unsw.edu.au/1959.4/63252 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:60027/SOURCE02?view=true.
MLA Handbook (7th Edition):
Zhang, Junqi. “Integrating geometric modeling and structure analysis: towards the digital future of engineering.” 2019. Web. 12 Apr 2021.
Vancouver:
Zhang J. Integrating geometric modeling and structure analysis: towards the digital future of engineering. [Internet] [Doctoral dissertation]. University of New South Wales; 2019. [cited 2021 Apr 12].
Available from: http://handle.unsw.edu.au/1959.4/63252 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:60027/SOURCE02?view=true.
Council of Science Editors:
Zhang J. Integrating geometric modeling and structure analysis: towards the digital future of engineering. [Doctoral Dissertation]. University of New South Wales; 2019. Available from: http://handle.unsw.edu.au/1959.4/63252 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:60027/SOURCE02?view=true
University of Houston
5.
Polat, Seckin 1988-.
Seismic Modeling and Imaging for Detection of Clandestine Tunnels.
Degree: MS, Geophysics, 2017, University of Houston
URL: http://hdl.handle.net/10657/4816
► Covert subterranean tunnels have especially been used for drug smuggling and illegal trading across country boarders such as the United States – Mexico, Egypt –…
(more)
▼ Covert subterranean tunnels have especially been used for drug smuggling and illegal trading across country boarders such as the United States – Mexico, Egypt – Israel and so on over the years. Conventional border security measures and intel activities of border security agencies remain insufficient in stopping these illegal underground passageways. During the 2016 U.S. presidential election, arguments were particularly focused on constructing a wall that contains sensors to locate possible existing and future clandestine tunnels between the U.S. and Mexico. The reliability of a specific scientific
method that can detect tunnel locations accurately has not been established yet. Among many proposed methods, seismic
method is a promising technique for imaging those tunnels, despite its many potential drawbacks, such as low signal-to-noise ratio (S/N), scattering, absorption, and heterogeneity of complex subsurface structures. Instead, by assigning proper parameters into
numerical modeling and projecting, the modeled results derived from these forward
numerical model examples may allow us to investigate the seismic detection capability under optimal conditions and various data acquisition geometries. The experience acquired from the
numerical modeling and imaging may lead us to locate the clandestine tunnels under realistic conditions. In our modeling, we use the elastic full-wave finite-element
method to simulate seismic wave interaction with subsurface tunnels. We test different frequencies and observational geometries including surface and borehole sources and receivers. We then used the modeled seismic data to implement the Kirchhoff migration. We have investigated various types of soils and boundary conditions. The modeling and imaging can help us define the optimal seismic data acquisition scheme for detecting subsurface voids and tunnels.
Advisors/Committee Members: Zheng, Yingcai (advisor), Castagna, John P. (committee member), Alkan, Engin (committee member).
Subjects/Keywords: Numerical models; Clandestine Tunnel; Finite element method
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Manager
APA (6th Edition):
Polat, S. 1. (2017). Seismic Modeling and Imaging for Detection of Clandestine Tunnels. (Masters Thesis). University of Houston. Retrieved from http://hdl.handle.net/10657/4816
Chicago Manual of Style (16th Edition):
Polat, Seckin 1988-. “Seismic Modeling and Imaging for Detection of Clandestine Tunnels.” 2017. Masters Thesis, University of Houston. Accessed April 12, 2021.
http://hdl.handle.net/10657/4816.
MLA Handbook (7th Edition):
Polat, Seckin 1988-. “Seismic Modeling and Imaging for Detection of Clandestine Tunnels.” 2017. Web. 12 Apr 2021.
Vancouver:
Polat S1. Seismic Modeling and Imaging for Detection of Clandestine Tunnels. [Internet] [Masters thesis]. University of Houston; 2017. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/10657/4816.
Council of Science Editors:
Polat S1. Seismic Modeling and Imaging for Detection of Clandestine Tunnels. [Masters Thesis]. University of Houston; 2017. Available from: http://hdl.handle.net/10657/4816
Delft University of Technology
6.
Schuringa, Johan (author).
Modelling the Installation of a Cone: Using a 2D-Axisymmetric Material Point Method Model.
Degree: 2020, Delft University of Technology
URL: http://resolver.tudelft.nl/uuid:1db732e7-fde1-4a2f-9912-46cdb4cd2c52
► In this work the installation process of a cone penetrating into a sand system is modelled using a 2D-axisymmetric material point method (MPM) model in…
(more)
▼ In this work the installation process of a cone penetrating into a sand system is modelled using a 2D-axisymmetric material point
method (MPM) model in order to investigate the installation processes and to predict the plastic radius. One meter of cone penetration is modelled under a surcharge of 50 kPa. The used constitutive model is Mohr-Coulomb Strain Softening (MCSS). The validation of the model has been conducted by comparing the MPM results to those obtained from laboratory experiments performed by Arshad et al. (2014). It was found that the qualitative behaviour from the MPM model and the experiments were in agreement but the quantitative behaviour showed some discrepancies. These discrepancies could be caused by the fact that, in the MCSS model, the stiffness is constant and independent of stress which it is not in reality. The performed sensitivity analysis showed that the stiffness has the most influence on the
numerical predictions further adding to the importance of accurately capturing the soil stiffness throughout the simulation. The 2D-axisymmetric MPM model showed to have the potential to be a good tool for modelling the installation process of a cone and predicting the plastic radius.
Advisors/Committee Members: Vardon, Phil (mentor), Pisano, Federico (graduation committee), Broere, Wout (graduation committee), Martinelli, Mario (graduation committee), Schadee, Leon (graduation committee), Delft University of Technology (degree granting institution).
Subjects/Keywords: Cone; Material Point Method; Pressuremeter; Numerical Modelling
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APA (6th Edition):
Schuringa, J. (. (2020). Modelling the Installation of a Cone: Using a 2D-Axisymmetric Material Point Method Model. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:1db732e7-fde1-4a2f-9912-46cdb4cd2c52
Chicago Manual of Style (16th Edition):
Schuringa, Johan (author). “Modelling the Installation of a Cone: Using a 2D-Axisymmetric Material Point Method Model.” 2020. Masters Thesis, Delft University of Technology. Accessed April 12, 2021.
http://resolver.tudelft.nl/uuid:1db732e7-fde1-4a2f-9912-46cdb4cd2c52.
MLA Handbook (7th Edition):
Schuringa, Johan (author). “Modelling the Installation of a Cone: Using a 2D-Axisymmetric Material Point Method Model.” 2020. Web. 12 Apr 2021.
Vancouver:
Schuringa J(. Modelling the Installation of a Cone: Using a 2D-Axisymmetric Material Point Method Model. [Internet] [Masters thesis]. Delft University of Technology; 2020. [cited 2021 Apr 12].
Available from: http://resolver.tudelft.nl/uuid:1db732e7-fde1-4a2f-9912-46cdb4cd2c52.
Council of Science Editors:
Schuringa J(. Modelling the Installation of a Cone: Using a 2D-Axisymmetric Material Point Method Model. [Masters Thesis]. Delft University of Technology; 2020. Available from: http://resolver.tudelft.nl/uuid:1db732e7-fde1-4a2f-9912-46cdb4cd2c52
Queens University
7.
Bespalko, Dustin John.
Validation of the Lattice Boltzmann Method for Direct Numerical Simulation of Wall-Bounded Turbulent Flows
.
Degree: Mechanical and Materials Engineering, 2011, Queens University
URL: http://hdl.handle.net/1974/6729
► In this work, the lattice Boltzmann method (LBM) was validated for direct numerical simulation (DNS) of wall-bounded turbulent flows. The LBM is a discrete-particle-based method…
(more)
▼ In this work, the lattice Boltzmann method (LBM) was validated for direct numerical simulation (DNS) of wall-bounded turbulent flows. The LBM is a discrete-particle-based method that numerically solves the Boltzmann equation as opposed to conventional DNS methods that are based on the Navier-Stokes (NS) equations. The advantages of the LBM are its simple implementation, its ability to handle complex geometries, and its scalability on modern high-performance computers.
An LBM code was developed and used to simulate fully-developed turbulent channel flow. In order to validate the results, the turbulence statistics were compared to those calculated from a conventional NS-based finite difference (FD) simulation. In the present study, special care was taken to make sure the computational domains for LBM and FD simulations were the same. Similar validation studies in the literature have used LBM simulations with smaller computational domains in order to reduce the computational cost. However, reducing the size of the computational domain affects the turbulence statistics and confounds the results of the validation.
The turbulence statistics calculated from the LBM and FD simulations were found to agree qualitatively; however, there were several significant deviations, particularly in the variance profiles. The largest discrepancy was in the variance of the pressure fluctuations, which differed by approximately 7%. Given that both the LBM and FD simulations resolved the full range of turbulent scales and no models were used, this error was deemed to be significant.
The cause of the discrepancy in the pressure variance was found to be the compressibility of the LBM. The LBM allows the density to vary, while the FD method does not since it solves the incompressible form of the NS equations. The effect of the compressibility could be reduced by lowering the Mach number, but this would come at the cost of significantly increasing the computational cost. Therefore, the conclusion of this work is that, while the LBM is capable of producing accurate solutions for incompressible turbulent flows, it is significantly more expensive than conventional methods for simple wall-bounded turbulent flows.
Subjects/Keywords: Lattice Boltzmann Method
;
Direct Numerical Simulation
;
Turbulence
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APA ·
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Export
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APA (6th Edition):
Bespalko, D. J. (2011). Validation of the Lattice Boltzmann Method for Direct Numerical Simulation of Wall-Bounded Turbulent Flows
. (Thesis). Queens University. Retrieved from http://hdl.handle.net/1974/6729
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Bespalko, Dustin John. “Validation of the Lattice Boltzmann Method for Direct Numerical Simulation of Wall-Bounded Turbulent Flows
.” 2011. Thesis, Queens University. Accessed April 12, 2021.
http://hdl.handle.net/1974/6729.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Bespalko, Dustin John. “Validation of the Lattice Boltzmann Method for Direct Numerical Simulation of Wall-Bounded Turbulent Flows
.” 2011. Web. 12 Apr 2021.
Vancouver:
Bespalko DJ. Validation of the Lattice Boltzmann Method for Direct Numerical Simulation of Wall-Bounded Turbulent Flows
. [Internet] [Thesis]. Queens University; 2011. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/1974/6729.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Bespalko DJ. Validation of the Lattice Boltzmann Method for Direct Numerical Simulation of Wall-Bounded Turbulent Flows
. [Thesis]. Queens University; 2011. Available from: http://hdl.handle.net/1974/6729
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Georgia
8.
Ettinger, Bree danielle.
Numerical integration for time scales.
Degree: 2014, University of Georgia
URL: http://hdl.handle.net/10724/21489
► Time Scale theory unifies and extends real and discrete analysis. Euler’s Method is an algorithm for constructing a linear approximation to the initial value problem…
(more)
▼ Time Scale theory unifies and extends real and discrete analysis. Euler’s Method is an algorithm for constructing a linear approximation to the initial value problem dy/dt = f(t, y) a < t < b and y(a) = a . Although Euler’s Method is
seldom used in practice, it lays the ground work for developing higher order approximation schemes. In this thesis, we use Euler’s Method to develop a numerical integration scheme for time scales. First we explore our numerical integration scheme on an
isolated time scale, and then extend our results to an arbitrary time scale. We also give error approximations for these schemes as well as examples.
Subjects/Keywords: Time scales; Euler\'s Method; Numerical Integration
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APA (6th Edition):
Ettinger, B. d. (2014). Numerical integration for time scales. (Thesis). University of Georgia. Retrieved from http://hdl.handle.net/10724/21489
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Ettinger, Bree danielle. “Numerical integration for time scales.” 2014. Thesis, University of Georgia. Accessed April 12, 2021.
http://hdl.handle.net/10724/21489.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Ettinger, Bree danielle. “Numerical integration for time scales.” 2014. Web. 12 Apr 2021.
Vancouver:
Ettinger Bd. Numerical integration for time scales. [Internet] [Thesis]. University of Georgia; 2014. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/10724/21489.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Ettinger Bd. Numerical integration for time scales. [Thesis]. University of Georgia; 2014. Available from: http://hdl.handle.net/10724/21489
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
9.
Shoemake, William L.
Linear elastic mesh deformation via localized orthotropic material properties optimized by the adjoint method.
Degree: 2017, University of Tennessee – Chattanooga
URL: https://scholar.utc.edu/theses/534
► The finite element method has been shown to be a powerful tool in computational engineering with recent application to electromagnetics and fluid dynamics. However, achieving…
(more)
▼ The finite element
method has been shown to be a powerful tool in computational engineering
with recent application to electromagnetics and fluid dynamics. However, achieving the
high orders of accuracy easily available to the finite element
method has proven difficult due to
conforming higher-order meshes to curved geometries. If higher-order nodes are not placed on the
surface of the geometry error is introduced into the simulated solution. This barrier is largely a
non-issue for inviscid meshes where a mid-edge node can be projected onto the nearest geometry
surface with minimal detrimental side effects. Viscous meshes however have to deform most of
the boundary layers in order to avoid inverting the surface elements and to maintain an acceptable
mesh quality. This research focuses on extending the application of the linear elastic analogy to
this mesh movement problem by attributing orthotropic material properties individually to each
node or element. This technique allows each node or element to behave differently under the
stress of conforming to the boundary. These localized material properties are determined using the
adjoint optimization
method. To better determine mesh quality, a new mesh metric called Metric3
is introduced. This new metric resembles the included angle metric and is based on an element’s
isoparametric transformation matrix.
Advisors/Committee Members: Hilbert, C. Bruce, Sreenivas, Kidambi, Matthews, Matt, Newman, James C., III, College of Engineering and Computer Science.
Subjects/Keywords: Numerical grid generation (Numerical analysis); Finite element method
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APA (6th Edition):
Shoemake, W. L. (2017). Linear elastic mesh deformation via localized orthotropic material properties optimized by the adjoint method. (Doctoral Dissertation). University of Tennessee – Chattanooga. Retrieved from https://scholar.utc.edu/theses/534
Chicago Manual of Style (16th Edition):
Shoemake, William L. “Linear elastic mesh deformation via localized orthotropic material properties optimized by the adjoint method.” 2017. Doctoral Dissertation, University of Tennessee – Chattanooga. Accessed April 12, 2021.
https://scholar.utc.edu/theses/534.
MLA Handbook (7th Edition):
Shoemake, William L. “Linear elastic mesh deformation via localized orthotropic material properties optimized by the adjoint method.” 2017. Web. 12 Apr 2021.
Vancouver:
Shoemake WL. Linear elastic mesh deformation via localized orthotropic material properties optimized by the adjoint method. [Internet] [Doctoral dissertation]. University of Tennessee – Chattanooga; 2017. [cited 2021 Apr 12].
Available from: https://scholar.utc.edu/theses/534.
Council of Science Editors:
Shoemake WL. Linear elastic mesh deformation via localized orthotropic material properties optimized by the adjoint method. [Doctoral Dissertation]. University of Tennessee – Chattanooga; 2017. Available from: https://scholar.utc.edu/theses/534
10.
Karman, Kristen.
Higher order mesh curving using geometry curvature extrapolation.
Degree: 2017, University of Tennessee – Chattanooga
URL: https://scholar.utc.edu/theses/533
► A higher order mesh curving method is developed which uses information from the geometry to determine the appropriate curvature of edges in the interior of…
(more)
▼ A higher order mesh curving
method is developed which uses information from the geometry to determine the appropriate curvature of edges in the interior of the mesh. Edges are represented using four point Bézier curves to determine the positions of higher order edge points. Higher order face and volume points are positioned using the basis functions for serendipity face and volume
elements. Parameters are defined which allow user specified control over element quality and the propagation of curvature in the mesh. Curved higher order meshes are shown for test cases in both two and three dimensions.
Advisors/Committee Members: Hilbert, C. Bruce, Newman, James C., III, Sreenivas, Kidambi, Matthews, Matt, College of Engineering and Computer Science.
Subjects/Keywords: Numerical grid generation (Numerical analysis); Finite element method
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APA (6th Edition):
Karman, K. (2017). Higher order mesh curving using geometry curvature extrapolation. (Doctoral Dissertation). University of Tennessee – Chattanooga. Retrieved from https://scholar.utc.edu/theses/533
Chicago Manual of Style (16th Edition):
Karman, Kristen. “Higher order mesh curving using geometry curvature extrapolation.” 2017. Doctoral Dissertation, University of Tennessee – Chattanooga. Accessed April 12, 2021.
https://scholar.utc.edu/theses/533.
MLA Handbook (7th Edition):
Karman, Kristen. “Higher order mesh curving using geometry curvature extrapolation.” 2017. Web. 12 Apr 2021.
Vancouver:
Karman K. Higher order mesh curving using geometry curvature extrapolation. [Internet] [Doctoral dissertation]. University of Tennessee – Chattanooga; 2017. [cited 2021 Apr 12].
Available from: https://scholar.utc.edu/theses/533.
Council of Science Editors:
Karman K. Higher order mesh curving using geometry curvature extrapolation. [Doctoral Dissertation]. University of Tennessee – Chattanooga; 2017. Available from: https://scholar.utc.edu/theses/533
11.
Liu, Tuo.
Automatic higher order mesh generation and movement utilizing spring-field and vector-adding.
Degree: 2017, University of Tennessee – Chattanooga
URL: https://scholar.utc.edu/theses/532
► In this research, an automatic, complex geometry applicable, unstructured curved 2D mesh generation method is developed. Based on this 2D method, an extension to 3D…
(more)
▼ In this research, an automatic, complex geometry applicable, unstructured curved 2D mesh generation
method is developed. Based on this 2D
method, an extension to 3D geometries is developed. The methodology of this mesh generation is to provide near-body and off-body meshes by an advancing-layer
method to avoid mesh quality problems in transition areas, while using spring models to complement the advancing-layers by smoothing the mesh, especially in medial axis regions. After generating the linear mesh, a higher-order finite-element ready, curved mesh is obtained by deforming the linear mesh through “pipes” using a simple Vector-Adding approach. Different from most curved viscous mesh generation approaches, this
method eschews a linear or nonlinear elasticity analogy while still providing positive-Jacobian mesh elements. In addition, the transformation from linear to curved meshes can be achieved by only deforming the necessary edges of the elements near domain boundaries while retaining the remaining non-curved edges to the benefit of
numerical solvers. The CFD results of 30P30N airfoil on the curved mesh are given and are in good agreement with the experimental data.
Further, a new
method for moving boundary problems with viscous mesh layers is also presented. This
method is an extension of the mesh generation approach above. It can be used not only for high-order mesh moving but also for high-order mesh generation. Also, based on the curved mesh deformation strategy, the
method can handle high-order mesh movement or regeneration with minimal extra computational time compared with linear mesh movement. Several 2D boundary motion cases are tested including boundary translations, boundary rotations, and boundary morphing. The CFD results on the curved mesh after rotation are given and are in good agreement with the experimental data. This technique is also tested through the optimization of an airfoil to achieve a maximized lift and drag ratio. The results demonstrate that this approach can handle large boundary movements while preserving a good mesh quality.
Advisors/Committee Members: Hilbert, C. Bruce, Newman, James C., III, Sreenivas, Kidambi, Karman, Steve L., Jr., College of Engineering and Computer Science.
Subjects/Keywords: Numerical grid generation (Numerical analysis); Finite element method – Data processing
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APA (6th Edition):
Liu, T. (2017). Automatic higher order mesh generation and movement utilizing spring-field and vector-adding. (Doctoral Dissertation). University of Tennessee – Chattanooga. Retrieved from https://scholar.utc.edu/theses/532
Chicago Manual of Style (16th Edition):
Liu, Tuo. “Automatic higher order mesh generation and movement utilizing spring-field and vector-adding.” 2017. Doctoral Dissertation, University of Tennessee – Chattanooga. Accessed April 12, 2021.
https://scholar.utc.edu/theses/532.
MLA Handbook (7th Edition):
Liu, Tuo. “Automatic higher order mesh generation and movement utilizing spring-field and vector-adding.” 2017. Web. 12 Apr 2021.
Vancouver:
Liu T. Automatic higher order mesh generation and movement utilizing spring-field and vector-adding. [Internet] [Doctoral dissertation]. University of Tennessee – Chattanooga; 2017. [cited 2021 Apr 12].
Available from: https://scholar.utc.edu/theses/532.
Council of Science Editors:
Liu T. Automatic higher order mesh generation and movement utilizing spring-field and vector-adding. [Doctoral Dissertation]. University of Tennessee – Chattanooga; 2017. Available from: https://scholar.utc.edu/theses/532
NSYSU
12.
Lin, Bing-han.
Method of fundamental solutions on simulating sloshing liquids in 2D tanks.
Degree: Master, Marine Environment and Engineering, 2018, NSYSU
URL: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0413118-191748
► A two dimension numerical model for sloshing response of the partially filled con- tainer is developed by a meshless method in this study. Laplace equation…
(more)
▼ A two dimension
numerical model for sloshing response of the partially filled con-
tainer is developed by a meshless
method in this study. Laplace equation is considered
as the governing equation for potential flow, and fully non-linear free surface boundary
conditions are implemented on the free surface. The
numerical model is established in
the moving coordinate system attached to the container. The present meshless
method,
method of fundamental solutions, only need to distribute nodes on the physical bound-
aries and the virtual boundaries outside the computational domain. Comparing with the
traditional mesh-based
numerical method, this
method has the advantage of being easy
to construct and flexible in dealing with the moving boundary problem. A preliminary
numerical validation was carried out by the case of a free oscillating standing wave. The
parameters such as the position of the virtual boundary, the number of nodes, and the time
step size are also determined.
The program is written in Python. A simple
method for tracking fully non-linear free
surface is implemented, and the physical boundaries are updated with time. The
numerical
results under horizontal motions were compared with the solutions of Chen and Chiang
(1999) and Frandsen (2004), respectively. The comparison shows that the presented re-
sults coincide with their solutions very well in both resonance and off-resonance cases.
The present
numerical model is further applied to the sloshing response under coupled
motions (horizontal and vertical). Based on the study of Benjamin and Ursell (1954) who
discussed the stability of sloshing response under vertical motion, 25 cases are conducted
in various sloshing parameters under coupled motions. The present
numerical model has
been successfully applied to investigating sloshing response under coupled motions.
Advisors/Committee Members: Shih-Meng Hsu (chair), Liang-hsiung Huang (chair), Bang-Fuh Chen (committee member), Chia-Cheng Tsai (chair).
Subjects/Keywords: Numerical tank; Nonlinear free surface; Method of fundamental solution; Meshless method
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CSE |
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to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Lin, B. (2018). Method of fundamental solutions on simulating sloshing liquids in 2D tanks. (Thesis). NSYSU. Retrieved from http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0413118-191748
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Lin, Bing-han. “Method of fundamental solutions on simulating sloshing liquids in 2D tanks.” 2018. Thesis, NSYSU. Accessed April 12, 2021.
http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0413118-191748.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Lin, Bing-han. “Method of fundamental solutions on simulating sloshing liquids in 2D tanks.” 2018. Web. 12 Apr 2021.
Vancouver:
Lin B. Method of fundamental solutions on simulating sloshing liquids in 2D tanks. [Internet] [Thesis]. NSYSU; 2018. [cited 2021 Apr 12].
Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0413118-191748.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Lin B. Method of fundamental solutions on simulating sloshing liquids in 2D tanks. [Thesis]. NSYSU; 2018. Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0413118-191748
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Guelph
13.
Althubyani, Mohammed.
Bounded and Positive Finite Element Approximations of Reaction-Diffusion Equations.
Degree: MS, Department of Mathematics and Statistics, 2013, University of Guelph
URL: https://atrium.lib.uoguelph.ca/xmlui/handle/10214/7513
► Traditionally, the numerical analysis of di erential equations focusses on stability, convergence and accuracy of the numerical methods employed. However in practice, there are other…
(more)
▼ Traditionally, the
numerical analysis of di erential equations focusses
on stability, convergence and accuracy of the
numerical methods employed.
However in practice, there are other features of the
numerical methods that
we are interested in. Generally, when we discretize a di erential equation,
we would like to preserve certain intrinsic characteristics of the model, for
example, positivity and boundedness of the quantities of interest. Consider-
able progress has been made in this area for the Finite Di erence
Method
(FDM), for example, the Non Standard Finite Di erence
Method (NSFDM).
However, little work has been done on preserving positivity and bounded-
ness for the
numerical solutions of the Finite Element
Method (FEM). In this
work we develop a general framework for achieving this aim, which is based
on the careful application of the Standard Galerkin FEM with 'Mass Lump-
ing'. For concreteness, we present results for the Heat Equation, The Fisher
reaction-di usion equation, and a coupled predator-prey reaction-di usion of
Rosenzweig-MacArthur form.
Advisors/Committee Members: Garvie, Marcus (advisor).
Subjects/Keywords: Numerical Analysis; Finite Difference Method; Finite Element Method
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APA (6th Edition):
Althubyani, M. (2013). Bounded and Positive Finite Element Approximations of Reaction-Diffusion Equations. (Masters Thesis). University of Guelph. Retrieved from https://atrium.lib.uoguelph.ca/xmlui/handle/10214/7513
Chicago Manual of Style (16th Edition):
Althubyani, Mohammed. “Bounded and Positive Finite Element Approximations of Reaction-Diffusion Equations.” 2013. Masters Thesis, University of Guelph. Accessed April 12, 2021.
https://atrium.lib.uoguelph.ca/xmlui/handle/10214/7513.
MLA Handbook (7th Edition):
Althubyani, Mohammed. “Bounded and Positive Finite Element Approximations of Reaction-Diffusion Equations.” 2013. Web. 12 Apr 2021.
Vancouver:
Althubyani M. Bounded and Positive Finite Element Approximations of Reaction-Diffusion Equations. [Internet] [Masters thesis]. University of Guelph; 2013. [cited 2021 Apr 12].
Available from: https://atrium.lib.uoguelph.ca/xmlui/handle/10214/7513.
Council of Science Editors:
Althubyani M. Bounded and Positive Finite Element Approximations of Reaction-Diffusion Equations. [Masters Thesis]. University of Guelph; 2013. Available from: https://atrium.lib.uoguelph.ca/xmlui/handle/10214/7513
University of Colorado
14.
Ashby, Ava.
The Study of Modeled Atomtronic Barrier Potentials Through the Impedance Method.
Degree: MS, Physics, 2016, University of Colorado
URL: https://scholar.colorado.edu/phys_gradetds/165
► The general impedance method developed by Khondker et.al [1] is applied to multiple barrier potentials to study the transmission behaviors of a single Gaussian…
(more)
▼ The general impedance
method developed by Khondker et.al [1] is applied to multiple barrier potentials to study the transmission behaviors of a single Gaussian barrier potential, double rectangular barrier potential, and a double Gaussian barrier potential. Using the impedance
method we will find quantum mechanical transmission behaviors like resonant tunneling for the quasi bound-states of the double barrier potentials. The single Gaussian barrier potential is an approximation for the atomtronic battery and the double Gaussian barrier potential is an approximation for the atomtronic transistor. Thus far, the atomtronic work presented in reference [2] was done in the classical regime where thermal currents dominate. The work presented in this thesis analyzes the quantum mechanical characteristics, such as tunneling, to be incorporated and perhaps used to explore coherent transistor action.
Advisors/Committee Members: Dana Anderson, Heather Lewandowski, Charles Rogers.
Subjects/Keywords: atomtronics; impedance method; numerical method; quantum mechanical transmission probablity; Physics
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Export
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Manager
APA (6th Edition):
Ashby, A. (2016). The Study of Modeled Atomtronic Barrier Potentials Through the Impedance Method. (Masters Thesis). University of Colorado. Retrieved from https://scholar.colorado.edu/phys_gradetds/165
Chicago Manual of Style (16th Edition):
Ashby, Ava. “The Study of Modeled Atomtronic Barrier Potentials Through the Impedance Method.” 2016. Masters Thesis, University of Colorado. Accessed April 12, 2021.
https://scholar.colorado.edu/phys_gradetds/165.
MLA Handbook (7th Edition):
Ashby, Ava. “The Study of Modeled Atomtronic Barrier Potentials Through the Impedance Method.” 2016. Web. 12 Apr 2021.
Vancouver:
Ashby A. The Study of Modeled Atomtronic Barrier Potentials Through the Impedance Method. [Internet] [Masters thesis]. University of Colorado; 2016. [cited 2021 Apr 12].
Available from: https://scholar.colorado.edu/phys_gradetds/165.
Council of Science Editors:
Ashby A. The Study of Modeled Atomtronic Barrier Potentials Through the Impedance Method. [Masters Thesis]. University of Colorado; 2016. Available from: https://scholar.colorado.edu/phys_gradetds/165
Rice University
15.
Shen, Bo.
A Discontinuous Galerkin Method for Two-phase Flow in Deformable Porous Media.
Degree: MA, Engineering, 2020, Rice University
URL: http://hdl.handle.net/1911/109397
► The proposed numerical scheme solves the linear poroelasticity equations, which refers to fluid flow within a deformable porous media under the assumption of relative small…
(more)
▼ The proposed
numerical scheme solves the linear poroelasticity equations, which refers to fluid flow within a deformable porous media under the assumption of relative small deformations. More precisely, we approximate the displacement of solid structure, the wetting phase pressure, and saturation of immiscible two-phase fluid flow in the deformable porous media in three dimensions. The model of linear poroelasticity is becoming increasingly essential in a diverse range of engineering fields such as the reservoir, biomedical, and environmental engineering. Thus predicting the deformation of the solid structure and the evolution of the phases in space and time plays an essential role in the risk-managing and decision-making process.
The proposed scheme solves the coupled equations sequentially while keeping each equation implicitly with respect to its unknown. A high-order interior penalty discontinuous Galerkin spatial discretization is combined with a backward Euler discretization in time. With this sequential approach, the equations are fully decoupled, which reduces the computational cost significantly compared to the existing implicit approach.
Numerical results show the convergence of the scheme with the expected rates.
Advisors/Committee Members: Riviere, Beatrice (advisor).
Subjects/Keywords: Poroelasticity; Multiphase flow; coupled flow; Geomechanics; Numerical method; Discontinuous Galerkin method
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Export
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Manager
APA (6th Edition):
Shen, B. (2020). A Discontinuous Galerkin Method for Two-phase Flow in Deformable Porous Media. (Masters Thesis). Rice University. Retrieved from http://hdl.handle.net/1911/109397
Chicago Manual of Style (16th Edition):
Shen, Bo. “A Discontinuous Galerkin Method for Two-phase Flow in Deformable Porous Media.” 2020. Masters Thesis, Rice University. Accessed April 12, 2021.
http://hdl.handle.net/1911/109397.
MLA Handbook (7th Edition):
Shen, Bo. “A Discontinuous Galerkin Method for Two-phase Flow in Deformable Porous Media.” 2020. Web. 12 Apr 2021.
Vancouver:
Shen B. A Discontinuous Galerkin Method for Two-phase Flow in Deformable Porous Media. [Internet] [Masters thesis]. Rice University; 2020. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/1911/109397.
Council of Science Editors:
Shen B. A Discontinuous Galerkin Method for Two-phase Flow in Deformable Porous Media. [Masters Thesis]. Rice University; 2020. Available from: http://hdl.handle.net/1911/109397
Washington State University
16.
[No author].
APPLICATIONS OF, AND ENHANCEMENTS TO, FINITE-DIFFERENCE-BASED SOLUTIONS TO PROBLEMS IN ELECTROMAGNETICS
.
Degree: 2013, Washington State University
URL: http://hdl.handle.net/2376/5057
► We describe how the analytic field propagation (AFP) technique can be coupled with a total-field/scattered-field (TFSF) boundary to obtain a novel implementation of a "gen-eralized"…
(more)
▼ We describe how the analytic field propagation (AFP) technique can be coupled with a total-field/scattered-field (TFSF) boundary to obtain a novel implementation of a "gen-eralized" total-field/scattered-field (G-TFSF) boundary. Using a G-TFSF boundary,one can directly model "infinite" objects, such as wedges, corners, and edges. Exampleapplications of the AFP-based G-TFSF technique are shown that model not just scatter-ing from wedges, but also scattering from 3D "defects" in wedges or edges. As describedin the thesis, the AFP-based G-TFSF
method described in this thesis possesses variousadvantages over the original G-TFSF
method presented by Anantha and Taflove [IEEETrans. Antennas and Propagat., 50(10):1337-1349, 2002].We revisit the long-standing debate surrounding whether or not "enhanced totalinternal reflection" (ETIR) is possible. ETIR implies that the magnitude of the reflectioncoefficient is greater than unity and is conjectured to be possible when a field is incidentfrom a lossless material to a gainy material beyond the critical angle. We examine thisproblem using FDTD modeling where the Poynting vector is used to examine the flowof energy. The two-dimensional simulations employ a Gaussian incident beam and makeno a priori assumptions about the reflection coefficient. We consider illumination ofgainy, lossless, and lossy materials. For gainy material, the magnitude of the reflectioncoefficient is found to be greater than unity, but there is a delay between when energyenters the gainy material and when the "excess" energy is reflected from the interface.Corona onset conditions in periodic micro- and nano-materials are analyzed via a dis-cretization of Gauss's Law. A
numerical model is developed to examine the mechanismby which nano-materials may provide superior performance relative to micro-materials.Starting from a single-cell layered structure, the electrical field distribution is computedusing the finite difference
method (FDM) and a sparse matrix solver. From these results,a general model is inferred by comparing results from the multi-cell layered structures tothe single-cell layered ones. Next, the corona onset condition is calculated for materialwith any particle size. Finally, the relationship between the breakdown voltage and theparticle size is derived based on the
numerical findings.
Advisors/Committee Members: Schneider, John B (advisor).
Subjects/Keywords: Electromagnetics;
Electrical engineering;
Computer science;
Electromagnetics;
FDTD method;
finite-difference method;
numerical method
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to Zotero / EndNote / Reference
Manager
APA (6th Edition):
author], [. (2013). APPLICATIONS OF, AND ENHANCEMENTS TO, FINITE-DIFFERENCE-BASED SOLUTIONS TO PROBLEMS IN ELECTROMAGNETICS
. (Thesis). Washington State University. Retrieved from http://hdl.handle.net/2376/5057
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
author], [No. “APPLICATIONS OF, AND ENHANCEMENTS TO, FINITE-DIFFERENCE-BASED SOLUTIONS TO PROBLEMS IN ELECTROMAGNETICS
.” 2013. Thesis, Washington State University. Accessed April 12, 2021.
http://hdl.handle.net/2376/5057.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
author], [No. “APPLICATIONS OF, AND ENHANCEMENTS TO, FINITE-DIFFERENCE-BASED SOLUTIONS TO PROBLEMS IN ELECTROMAGNETICS
.” 2013. Web. 12 Apr 2021.
Vancouver:
author] [. APPLICATIONS OF, AND ENHANCEMENTS TO, FINITE-DIFFERENCE-BASED SOLUTIONS TO PROBLEMS IN ELECTROMAGNETICS
. [Internet] [Thesis]. Washington State University; 2013. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/2376/5057.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
author] [. APPLICATIONS OF, AND ENHANCEMENTS TO, FINITE-DIFFERENCE-BASED SOLUTIONS TO PROBLEMS IN ELECTROMAGNETICS
. [Thesis]. Washington State University; 2013. Available from: http://hdl.handle.net/2376/5057
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
17.
Owen, Benjamin Joseph.
Development of a discrete fluid-structure interaction
method for cardiovascular applications.
Degree: 2019, University of Manchester
URL: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:320620
► The interaction between blood and cardiovascular tissue is known to play a significant role in the development cardiovascular diseases and associated conditions. With the ever…
(more)
▼ The interaction between blood and cardiovascular
tissue is known to play a significant role in the development
cardiovascular diseases and associated conditions. With the ever
increasing availability and performance of computational resources,
in conjunction with improved understanding of the disease
mechanisms, the integration of
numerical analysis into in silico
tools has become more prevalent. Once viewed as emerging
technology, these tools are now being routinely utilised in
clinical practice. However, the majority of these tools consider
the fluid or structure in isolation. This is due to the added
complexity of coupling the methods and the computational cost
incurred through modelling fluid-structure interaction using
traditional continuum methods. As a result, discretisations of the
structure used in fluid-structure interaction (FSI) methods tend to
be simpler representations and offer limited potential to model
complex non-linear material properties and discrete effects such as
rupture. The purpose of this work is to develop an efficient
fluid-structure interaction
method capable of modelling complex
phenomena. The inherent parallel performance of discrete
numerical
methods is explored, with a long-term view to developing the
method
for use in clinical tools; where speed, robustness and adaptability
are paramount. In the present work, the fluid is represented via
the lattice Boltzmann
method and the structure via the vector-based
discrete element
method, known as the V-model. These solvers are
strongly coupled using a version of the immersed boundary
method
based on direct forcing in a block Gauss-Seidel scheme, where the
time step size of the fluid and structure are to be kept
independent. Validation results for the V-model show good agreement
with analytical and
numerical solutions for static and dynamic
cantilever beam cases with constant and time-varying external
loads. This demonstrates the V-model's ability to accurately
capture the mechanical response of a material before extending the
method to model more complex physics. GPU implementation of the
V-model demonstrated speed-ups of x50 relative to an optimised
serial CPU implementation. The FSI
method demonstrated good
agreement with
numerical benchmark data while stochastic modelling
of the structure material properties demonstrated the V-model's
potential to model variation in cardiovascular tissue that occurs
naturally and due to disease. The major original contributions of
this work include the implementation and elucidation of a recently
developed structure model; which is used here for the first time
with a lattice Boltzmann scheme. The work also provides first steps
towards the use of stochastic modelling using the V-model, the
first GPU implementation of the V-model, and development of the
first strongly coupled fluid-structure interaction
method to
include the V-model.
Advisors/Committee Members: BOJDO, NICHOLAS NM, KEAVNEY, BERNARD B, HARWOOD, ADRIAN ARG, Revell, Alistair, Bojdo, Nicholas, Keavney, Bernard, Harwood, Adrian.
Subjects/Keywords: fluid-structure interaction; numerical modelling; GPU; discrete element method; lattice Boltzmann method; immersed boundary method
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MLA ·
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Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Owen, B. J. (2019). Development of a discrete fluid-structure interaction
method for cardiovascular applications. (Doctoral Dissertation). University of Manchester. Retrieved from http://www.manchester.ac.uk/escholar/uk-ac-man-scw:320620
Chicago Manual of Style (16th Edition):
Owen, Benjamin Joseph. “Development of a discrete fluid-structure interaction
method for cardiovascular applications.” 2019. Doctoral Dissertation, University of Manchester. Accessed April 12, 2021.
http://www.manchester.ac.uk/escholar/uk-ac-man-scw:320620.
MLA Handbook (7th Edition):
Owen, Benjamin Joseph. “Development of a discrete fluid-structure interaction
method for cardiovascular applications.” 2019. Web. 12 Apr 2021.
Vancouver:
Owen BJ. Development of a discrete fluid-structure interaction
method for cardiovascular applications. [Internet] [Doctoral dissertation]. University of Manchester; 2019. [cited 2021 Apr 12].
Available from: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:320620.
Council of Science Editors:
Owen BJ. Development of a discrete fluid-structure interaction
method for cardiovascular applications. [Doctoral Dissertation]. University of Manchester; 2019. Available from: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:320620
University of Cambridge
18.
Rockstroh , Parousia.
Boundary Value Problems for the Laplace Equation on Convex Domains with Analytic Boundary.
Degree: PhD, 2018, University of Cambridge
URL: https://www.repository.cam.ac.uk/handle/1810/273939
► In this thesis we study boundary value problems for the Laplace equation on do mains with smooth boundary. Central to our analysis is a relation,…
(more)
▼ In this thesis we study boundary value problems for the Laplace equation on do
mains with smooth boundary. Central to our analysis is a relation, known as the global
relation, that couples the boundary data for a given BVP. Previously, the global re
lation has primarily been applied to elliptic PDEs defined on polygonal domains. In
this thesis we extend the use of the global relation to domains with smooth boundary. This is done by introducing a new transform, denoted by F_p, that is an analogue of the Fourier transform on smooth convex curves. We show that the F_p-transform is a bounded and invertible integral operator. Following this, we show that the F_p-transform naturally arises in the global relation for the Laplace equation on domains with smooth boundary. Using properties of the F_p-transform, we show that the global relation defines a continuously invertible map between the Dirichlet and Neumann data
for a given BVP for the Laplace equation. Following this, we construct a numerical
method that uses the global relation to find the Neumann data, given the Dirichlet
data, for a given BVP for the Laplace equation on a domain with smooth boundary.
Subjects/Keywords: Partial Differential Equations; Laplace Equation; Fokas Method; Unified Transform Method; Elliptic PDEs; Numerical Method
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APA (6th Edition):
Rockstroh , P. (2018). Boundary Value Problems for the Laplace Equation on Convex Domains with Analytic Boundary. (Doctoral Dissertation). University of Cambridge. Retrieved from https://www.repository.cam.ac.uk/handle/1810/273939
Chicago Manual of Style (16th Edition):
Rockstroh , Parousia. “Boundary Value Problems for the Laplace Equation on Convex Domains with Analytic Boundary.” 2018. Doctoral Dissertation, University of Cambridge. Accessed April 12, 2021.
https://www.repository.cam.ac.uk/handle/1810/273939.
MLA Handbook (7th Edition):
Rockstroh , Parousia. “Boundary Value Problems for the Laplace Equation on Convex Domains with Analytic Boundary.” 2018. Web. 12 Apr 2021.
Vancouver:
Rockstroh P. Boundary Value Problems for the Laplace Equation on Convex Domains with Analytic Boundary. [Internet] [Doctoral dissertation]. University of Cambridge; 2018. [cited 2021 Apr 12].
Available from: https://www.repository.cam.ac.uk/handle/1810/273939.
Council of Science Editors:
Rockstroh P. Boundary Value Problems for the Laplace Equation on Convex Domains with Analytic Boundary. [Doctoral Dissertation]. University of Cambridge; 2018. Available from: https://www.repository.cam.ac.uk/handle/1810/273939
19.
Owen, Benjamin.
Development of a discrete fluid-structure interaction method for cardiovascular applications.
Degree: PhD, 2019, University of Manchester
URL: https://www.research.manchester.ac.uk/portal/en/theses/development-of-a-discrete-fluidstructure-interaction-method-for-cardiovascular-applications(9e018b74-f810-4201-8a26-2f4d91d34efa).html
;
https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.785672
► The interaction between blood and cardiovascular tissue is known to play a significant role in the development cardiovascular diseases and associated conditions. With the ever…
(more)
▼ The interaction between blood and cardiovascular tissue is known to play a significant role in the development cardiovascular diseases and associated conditions. With the ever increasing availability and performance of computational resources, in conjunction with improved understanding of the disease mechanisms, the integration of numerical analysis into in silico tools has become more prevalent. Once viewed as emerging technology, these tools are now being routinely utilised in clinical practice. However, the majority of these tools consider the fluid or structure in isolation. This is due to the added complexity of coupling the methods and the computational cost incurred through modelling fluid-structure interaction using traditional continuum methods. As a result, discretisations of the structure used in fluid-structure interaction (FSI) methods tend to be simpler representations and offer limited potential to model complex non-linear material properties and discrete effects such as rupture. The purpose of this work is to develop an efficient fluid-structure interaction method capable of modelling complex phenomena. The inherent parallel performance of discrete numerical methods is explored, with a long-term view to developing the method for use in clinical tools; where speed, robustness and adaptability are paramount. In the present work, the fluid is represented via the lattice Boltzmann method and the structure via the vector-based discrete element method, known as the V-model. These solvers are strongly coupled using a version of the immersed boundary method based on direct forcing in a block Gauss-Seidel scheme, where the time step size of the fluid and structure are to be kept independent. Validation results for the V-model show good agreement with analytical and numerical solutions for static and dynamic cantilever beam cases with constant and time-varying external loads. This demonstrates the V-model's ability to accurately capture the mechanical response of a material before extending the method to model more complex physics. GPU implementation of the V-model demonstrated speed-ups of x50 relative to an optimised serial CPU implementation. The FSI method demonstrated good agreement with numerical benchmark data while stochastic modelling of the structure material properties demonstrated the V-model's potential to model variation in cardiovascular tissue that occurs naturally and due to disease. The major original contributions of this work include the implementation and elucidation of a recently developed structure model; which is used here for the first time with a lattice Boltzmann scheme. The work also provides first steps towards the use of stochastic modelling using the V-model, the first GPU implementation of the V-model, and development of the first strongly coupled fluid-structure interaction method to include the V-model.
Subjects/Keywords: immersed boundary method; discrete element method; lattice Boltzmann method; numerical modelling; fluid-structure interaction; GPU
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APA ·
Chicago ·
MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
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APA (6th Edition):
Owen, B. (2019). Development of a discrete fluid-structure interaction method for cardiovascular applications. (Doctoral Dissertation). University of Manchester. Retrieved from https://www.research.manchester.ac.uk/portal/en/theses/development-of-a-discrete-fluidstructure-interaction-method-for-cardiovascular-applications(9e018b74-f810-4201-8a26-2f4d91d34efa).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.785672
Chicago Manual of Style (16th Edition):
Owen, Benjamin. “Development of a discrete fluid-structure interaction method for cardiovascular applications.” 2019. Doctoral Dissertation, University of Manchester. Accessed April 12, 2021.
https://www.research.manchester.ac.uk/portal/en/theses/development-of-a-discrete-fluidstructure-interaction-method-for-cardiovascular-applications(9e018b74-f810-4201-8a26-2f4d91d34efa).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.785672.
MLA Handbook (7th Edition):
Owen, Benjamin. “Development of a discrete fluid-structure interaction method for cardiovascular applications.” 2019. Web. 12 Apr 2021.
Vancouver:
Owen B. Development of a discrete fluid-structure interaction method for cardiovascular applications. [Internet] [Doctoral dissertation]. University of Manchester; 2019. [cited 2021 Apr 12].
Available from: https://www.research.manchester.ac.uk/portal/en/theses/development-of-a-discrete-fluidstructure-interaction-method-for-cardiovascular-applications(9e018b74-f810-4201-8a26-2f4d91d34efa).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.785672.
Council of Science Editors:
Owen B. Development of a discrete fluid-structure interaction method for cardiovascular applications. [Doctoral Dissertation]. University of Manchester; 2019. Available from: https://www.research.manchester.ac.uk/portal/en/theses/development-of-a-discrete-fluidstructure-interaction-method-for-cardiovascular-applications(9e018b74-f810-4201-8a26-2f4d91d34efa).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.785672
University of California – Berkeley
20.
Hermes, Daniel Jerome.
High-order Solution Transfer between Curved Meshes and Ill-conditioned Bézier Curve Intersection.
Degree: Applied Mathematics, 2018, University of California – Berkeley
URL: http://www.escholarship.org/uc/item/2p38w1w6
► The problem of solution transfer between meshes arises frequently in computational physics, e.g. in Lagrangian methods where remeshing occurs. The interpolation process must be conservative,…
(more)
▼ The problem of solution transfer between meshes arises frequently in computational physics, e.g. in Lagrangian methods where remeshing occurs. The interpolation process must be conservative, i.e. it must conserve physical properties, such as mass. We extend previous works – which described the solution transfer process for straight sided unstructured meshes – by considering high-order isoparametric meshes with curved elements. The implementation is highly reliant on accurate computational geometry routines for evaluating points on and intersecting Bézier curves and triangles.Two ill-conditioned problems that occur evaluating points on and intersecting Bézier curves are then explored. This work presents a family of compensated algorithms to accurately evaluate a polynomial in Bernstein form with floating point coefficients. The principle is to apply error-free transformations to improve the traditional de Casteljau algorithm. The resulting output is as accurate as the de Casteljau algorithm performed in K times the working precision. After compensated evaluation is considered, a compensated Newton's method is described, both for root-finding for polynomials in the Bernstein basis and for Bézier curve intersection.
Subjects/Keywords: Applied mathematics; Bezier Curve Intersection; Compensated Algorithm; Lagrangian Method; Numerical Analysis; Numerical Quadrature; Solution Transfer
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APA ·
Chicago ·
MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
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APA (6th Edition):
Hermes, D. J. (2018). High-order Solution Transfer between Curved Meshes and Ill-conditioned Bézier Curve Intersection. (Thesis). University of California – Berkeley. Retrieved from http://www.escholarship.org/uc/item/2p38w1w6
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Hermes, Daniel Jerome. “High-order Solution Transfer between Curved Meshes and Ill-conditioned Bézier Curve Intersection.” 2018. Thesis, University of California – Berkeley. Accessed April 12, 2021.
http://www.escholarship.org/uc/item/2p38w1w6.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Hermes, Daniel Jerome. “High-order Solution Transfer between Curved Meshes and Ill-conditioned Bézier Curve Intersection.” 2018. Web. 12 Apr 2021.
Vancouver:
Hermes DJ. High-order Solution Transfer between Curved Meshes and Ill-conditioned Bézier Curve Intersection. [Internet] [Thesis]. University of California – Berkeley; 2018. [cited 2021 Apr 12].
Available from: http://www.escholarship.org/uc/item/2p38w1w6.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Hermes DJ. High-order Solution Transfer between Curved Meshes and Ill-conditioned Bézier Curve Intersection. [Thesis]. University of California – Berkeley; 2018. Available from: http://www.escholarship.org/uc/item/2p38w1w6
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Université Catholique de Louvain
21.
Hubert, Simon.
Numerical analysis of strongly coupled antenna arrays and metasurfaces.
Degree: 2018, Université Catholique de Louvain
URL: http://hdl.handle.net/2078.1/198381
► Nowadays, communication technologies form an essential part of our everyday lives. Antenna systems receive thus more and more attention from both industrial and academic actors.…
(more)
▼ Nowadays, communication technologies form an essential part of our everyday lives. Antenna systems receive thus more and more attention from both industrial and academic actors. These modern technologies are increasingly complex, and require fast prototyping and benchmarking in their design process. Numerical methods play a key role in that perspective, by providing an accurate estimation of the performance at low cost. However, the computation time and memory required by these electromagnetic simulators remain prohibitively high for certain classes of problems. This thesis focuses on the development of specialized numerical methods, with the goal of mitigating their computational cost. The proposed methods are physics-based optimizations of the Method of Moments, which has been ubiquitous in the analysis of planar and metallic antenna structures. Motivated by the recent and exciting advances in the field of metasurface antennas, the main part of the dissertation is dedicated to planar structures. The contributions range from essentially theoretical results, such as mathematical links between well-established antenna theory results; to efficient solvers exploiting the Contour-FFT for the analysis of large planar arbitrary arrays; to the development of miniaturized shielded arrays for localization applications.
(FSA - Sciences de l'ingénieur) – UCL, 2018
Advisors/Committee Members: UCL - SST/ICTM/ELEN - Pôle en ingénierie électrique, UCL - Ecole Polytechnique de Louvain, Craeye, Christophe, Oestges, Claude, Bol, David, Gilles, Thierry, Hum, Sean, Mesa, Francisco.
Subjects/Keywords: Antenna; Metasurface; Electromagnetics; Computational electromagnetics; Antenna array; Numerical method; Algorithm; Simulation; Mutual coupling; Numerical analysis
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APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Hubert, S. (2018). Numerical analysis of strongly coupled antenna arrays and metasurfaces. (Thesis). Université Catholique de Louvain. Retrieved from http://hdl.handle.net/2078.1/198381
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Hubert, Simon. “Numerical analysis of strongly coupled antenna arrays and metasurfaces.” 2018. Thesis, Université Catholique de Louvain. Accessed April 12, 2021.
http://hdl.handle.net/2078.1/198381.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Hubert, Simon. “Numerical analysis of strongly coupled antenna arrays and metasurfaces.” 2018. Web. 12 Apr 2021.
Vancouver:
Hubert S. Numerical analysis of strongly coupled antenna arrays and metasurfaces. [Internet] [Thesis]. Université Catholique de Louvain; 2018. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/2078.1/198381.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Hubert S. Numerical analysis of strongly coupled antenna arrays and metasurfaces. [Thesis]. Université Catholique de Louvain; 2018. Available from: http://hdl.handle.net/2078.1/198381
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
22.
Vitor Alves Pires.
Método híbrido de alta ordem para escoamentos compressíveis.
Degree: 2015, University of São Paulo
URL: http://www.teses.usp.br/teses/disponiveis/55/55134/tde-18102016-162530/
► A presença de onda de choque e vórtices de pequena escala exigem métodos numéricos mais sofisticados para simular escoamentos compressíveis em velocidades altas. Alguns desses…
(more)
▼ A presença de onda de choque e vórtices de pequena escala exigem métodos numéricos mais sofisticados para simular escoamentos compressíveis em velocidades altas. Alguns desses métodos produzem resultados adequados para regiões com função suave, embora os mesmos não possam ser utilizados diretamente em regiões com função descontínua, resultando em oscilações espúrias. Dessa forma, métodos foram desenvolvidos para solucionar esse problema, apresentando um bom desempenho para regiões com função descontínua; entretanto, estes possuem termos de alta dissipação. Para evitar os problemas encontrados, foram desenvolvidos os métodos híbridos, onde dois métodos com características ideais para cada região são combinados através de uma função detectora que analisa numericamente a variação de uma quantidade em uma região através de fórmulas que envolvem derivadas. Um detector de descontinuidades foi desenvolvido a partir da revisão bibliográfica de diversos
métodos numéricos híbridos existentes, sendo avaliadas as principais desvantagens e limitações de cada um. Diversas comparações entre o novo detector e os detectores de descontinuidades já desenvolvidos foram realizadas através da aplicação em funções unidimensionais e bidimensionais. Finalmente, o método híbrido foi aplicado para a solução das equações de Euler unidimensionais e bidimensionais.
The presence of shock and small-scale vortices require more sophisticated numerical methods to simulate compressible flows at high speeds. Some of these methods produce good results for regions with smooth function, altough they cannot be used directly in regions with discontinuous functions, resulting in spurious oscillations. Thus, methods have been developed to solve this problem, showing a good performance for regions with discontinuous functions; however, these methods contain high dissipation terms. To avoid the problems encountered, hybrid methods have been developed, where two
methods with ideal characteristics for each region are combined through a function that analyze numerically the variation of a quantity in the region using formulas involving derivatives. A discontinuity detector was developed from the literature review of several existing hybrid methods, evaluating the main disadvantages and limitations of each. The new detector and other developed discontinuity detectors were compared by applying on one and two-dimensional functions. Finally, the hybrid method was applied fo the solution of one and twodimensional Euler equations.
Advisors/Committee Members: Maria Luísa Bambozzi de Oliveira, Leandro Franco de Souza, João Marcelo Vedovoto.
Subjects/Keywords: Análise numérica; Equações diferenciais parciais; Métodos numéricos; Numerical analysis; Numerical method; Partial differential equations
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APA (6th Edition):
Pires, V. A. (2015). Método híbrido de alta ordem para escoamentos compressíveis. (Masters Thesis). University of São Paulo. Retrieved from http://www.teses.usp.br/teses/disponiveis/55/55134/tde-18102016-162530/
Chicago Manual of Style (16th Edition):
Pires, Vitor Alves. “Método híbrido de alta ordem para escoamentos compressíveis.” 2015. Masters Thesis, University of São Paulo. Accessed April 12, 2021.
http://www.teses.usp.br/teses/disponiveis/55/55134/tde-18102016-162530/.
MLA Handbook (7th Edition):
Pires, Vitor Alves. “Método híbrido de alta ordem para escoamentos compressíveis.” 2015. Web. 12 Apr 2021.
Vancouver:
Pires VA. Método híbrido de alta ordem para escoamentos compressíveis. [Internet] [Masters thesis]. University of São Paulo; 2015. [cited 2021 Apr 12].
Available from: http://www.teses.usp.br/teses/disponiveis/55/55134/tde-18102016-162530/.
Council of Science Editors:
Pires VA. Método híbrido de alta ordem para escoamentos compressíveis. [Masters Thesis]. University of São Paulo; 2015. Available from: http://www.teses.usp.br/teses/disponiveis/55/55134/tde-18102016-162530/
Stellenbosch University
23.
Buitendag, Sven.
The saddle-point method and its application to the hill estimator.
Degree: MCom, Statistics, 2016, Stellenbosch University
URL: http://hdl.handle.net/10019.1/100057
► ENGLISH SUMMARY : The saddle-point approximation is a highly accurate approximation of the distribution of a random variable. It was originally derived as an approximation…
(more)
▼ ENGLISH SUMMARY : The saddle-point approximation is a highly accurate approximation of the distribution of a random variable. It was originally derived as an approximation in situations where a parameter takes on large values. However, due to its high accuracy and good behaviour in a variety of applications not involving such a parameter, it has been generalized and applied to the distribution of any random variable with a well-behaved cumulant generating function. In this thesis the theory underlying the saddle-point approximation will be discussed and illustrated with an application to approximate the distribution of the Hill estimator in extreme value theory.
AFRIKAANSE OPSOMMING : Die saalpunt-benadering is 'n hoogs noukeurige benadering van die verdeling van 'n stochastiese veranderlike. Dit is oorspronklik afgelei as 'n benadering in gevalle waar 'n parameter groot waardes aanneem. Nietemin, na aanleiding van sy hoogs akkurate aard en goeie gedrag in 'n verskeidenheid van toepassings wat nie betrekking het op so 'n parameter nie, is dit veralgemeen en toegepas op die verdeling van enige stochastiese veranderlike met 'n kumulantvoortbringende funksie wat goeie gedrag toon. In hierdie tesis sal die teorie onderliggend aan die saalpunt-benadering bespreek en gellustreer word met 'n toepassing om die verdeling van die Hill-beramer te benader.
Advisors/Committee Members: De Wet, Tertius, Stellenbosch University. Faculty of Economic and Management Sciences. Dept. of Statistics & Actuarial Science..
Subjects/Keywords: Saddle point method (Numerical analysis); Hill estimator; Method of steepest descent (Numerical analysis); Edgeworth expansions; Extreme value theory; UCTD
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APA ·
Chicago ·
MLA ·
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CSE |
Export
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APA (6th Edition):
Buitendag, S. (2016). The saddle-point method and its application to the hill estimator. (Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/100057
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Buitendag, Sven. “The saddle-point method and its application to the hill estimator.” 2016. Thesis, Stellenbosch University. Accessed April 12, 2021.
http://hdl.handle.net/10019.1/100057.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Buitendag, Sven. “The saddle-point method and its application to the hill estimator.” 2016. Web. 12 Apr 2021.
Vancouver:
Buitendag S. The saddle-point method and its application to the hill estimator. [Internet] [Thesis]. Stellenbosch University; 2016. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/10019.1/100057.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Buitendag S. The saddle-point method and its application to the hill estimator. [Thesis]. Stellenbosch University; 2016. Available from: http://hdl.handle.net/10019.1/100057
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Johannes Gutenberg Universität Mainz
24.
Götz, Daniel.
Helicity methods in LO and NLO QCD calculations.
Degree: 2014, Johannes Gutenberg Universität Mainz
URL: http://ubm.opus.hbz-nrw.de/volltexte/2014/3856/
► The goal of this thesis is the acceleration of numerical calculations of QCD observables, both at leading order and next–to–leading order in the coupling constant.…
(more)
▼ The goal of this thesis is the acceleration of numerical calculations of QCD observables, both at leading order and next–to–leading order in the coupling constant. In particular, the optimization of helicity and spin summation in the context of VEGAS Monte Carlo algorithms is investigated. In the literature, two such methods are mentioned but without detailed analyses. Only one of these methods can be used at next–to–leading order. This work presents a total of five different methods that replace the helicity sums with a Monte Carlo integration. This integration can be combined with the existing phase space integral, in the hope that this causes less overhead than the complete summation. For three of these methods, an extension to existing subtraction terms is developed which is required to enable next–to–leading order calculations. All methods are analyzed with respect to efficiency, accuracy, and ease of implementation before they are compared with each other. In this process, one method shows clear advantages in relation to all others.
Ziel dieser Arbeit ist es, die numerische Berechnung von QCD Observablen sowohl auf führender Ordnung als auch auf nächst-führender Ordnung in der Kopplungskonstante zu beschleunigen. Konkret wird eine solche Optimierung im Gebiet der Helizitäts- und Spinsummen im Zusammenhang mit dem VEGAS-Monte-Carlo-Algorithmus untersucht. In der Literatur werden zwei solcher Methoden erwähnt, jedoch ohne detaillierte Analysen. Nur eine dieser Methoden ist auf die nächst-führende Ordnung anwendbar. Diese Arbeit stellt insgesamt fünf verschiedene Methoden vor, welche die Helizitätssummen durch eine Monte-Carlo-Integration ersetzen. Diese kann mit dem existierenden Phasenraumintegral kombiniert werden, in der Hoffnung dass dies einen geringeren Mehraufwand als die vollständige Summation bietet. Für drei der Methoden wird eine Erweiterung von existierenden Subtraktionstermen entwickelt, die auf nächst-führender Ordnung benötigt wird. Alle Methoden werden analysiert im Bezug auf Effizienz, Genauigkeit und Implementierbarkeit, und anschließend verglichen. Dabei zeigt eine Methode klare Vorteile vor allen anderen.
Subjects/Keywords: Helizitätsmethode, Subtraktionsmethode, Numerische Methoden; Helicity method, subtraction method, numerical methods, random polarizations; Physics
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APA ·
Chicago ·
MLA ·
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Export
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Manager
APA (6th Edition):
Götz, D. (2014). Helicity methods in LO and NLO QCD calculations. (Doctoral Dissertation). Johannes Gutenberg Universität Mainz. Retrieved from http://ubm.opus.hbz-nrw.de/volltexte/2014/3856/
Chicago Manual of Style (16th Edition):
Götz, Daniel. “Helicity methods in LO and NLO QCD calculations.” 2014. Doctoral Dissertation, Johannes Gutenberg Universität Mainz. Accessed April 12, 2021.
http://ubm.opus.hbz-nrw.de/volltexte/2014/3856/.
MLA Handbook (7th Edition):
Götz, Daniel. “Helicity methods in LO and NLO QCD calculations.” 2014. Web. 12 Apr 2021.
Vancouver:
Götz D. Helicity methods in LO and NLO QCD calculations. [Internet] [Doctoral dissertation]. Johannes Gutenberg Universität Mainz; 2014. [cited 2021 Apr 12].
Available from: http://ubm.opus.hbz-nrw.de/volltexte/2014/3856/.
Council of Science Editors:
Götz D. Helicity methods in LO and NLO QCD calculations. [Doctoral Dissertation]. Johannes Gutenberg Universität Mainz; 2014. Available from: http://ubm.opus.hbz-nrw.de/volltexte/2014/3856/
Queens University
25.
Jabbari Sahebari, Aidin.
Analysis of Idealized Numerical Simulations to Calibrate and Validate Boundary Layer Models
.
Degree: Civil Engineering, 2015, Queens University
URL: http://hdl.handle.net/1974/13568
► The accuracy of the inertial dissipation method (IDM), commonly applied to estimate the observed rate of turbulent dissipation in bottom boundary layers (BBL), is evaluated…
(more)
▼ The accuracy of the inertial dissipation method (IDM), commonly applied to estimate the observed rate of turbulent dissipation in bottom boundary layers (BBL), is evaluated by performing direct numerical simulations (DNS) and large eddy simulations (LES) of unidirectional turbulent channel flows. Errors in the IDM occur as the mean velocity is commonly used for the convection velocity and when the canonical Kolmogorov -5/3 constants, which assume isotropy and homogeneity of the flow, are applied. The optimal convection velocity, as previously shown by many researchers, is found to be 2 times greater than the local mean velocity near the bed and the Kolmogorov constants are significantly affected by anisotropy. Usage of the canonical Kolmogorov constants leads to significant errors (>50%) in computation of dissipation.
Using the same DNS and LES data, the accuracy of Kolmogorov 2/3 constants, used in the structure function method (SFM) to compute dissipation, is also investigated. As with the IDM, comparison of the dissipation, calculated directly from DNS/LES with that from the SFM, shows that usage of canonical constants results in considerable error (>50%) from the vertical or spanwise velocity components. Application of anisotropy-adjusted constants to data from the BBL of Lake Erie shows that these constants improve computed dissipation by a factor of two, with results within 20% of published dissipation obtained from the Batchelor fitting method.
DNS and LES of oscillating turbulent flows were also carried out to calibrate and evaluate common analytical models used in oscillatory BBLs in lakes and costal oceans. These include the log-law, Stokes second problem, the IDM, and a one-equation Spalart-Allmaras model. Velocity profile predictions from the Spalart-Allmaras model were found to be more accurate than those from the log-law and Stokes’ second problem. Comparison of the LES data and the turbulence models, with published field measurements, shows that the rate of dissipation from the IDM is more accurate than that obtained from the log-law, particularly when the flow reverses. The differences between the IDM and LES suggest that the errors in prediction of dissipation can be due to the anisotropy conditions in the BBL.
Subjects/Keywords: Structure Function Method
;
Direct Numerical Simulations
;
Inertial Dissipation Method
;
Large Eddy Simulations
;
Boundary Layers
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APA (6th Edition):
Jabbari Sahebari, A. (2015). Analysis of Idealized Numerical Simulations to Calibrate and Validate Boundary Layer Models
. (Thesis). Queens University. Retrieved from http://hdl.handle.net/1974/13568
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Jabbari Sahebari, Aidin. “Analysis of Idealized Numerical Simulations to Calibrate and Validate Boundary Layer Models
.” 2015. Thesis, Queens University. Accessed April 12, 2021.
http://hdl.handle.net/1974/13568.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Jabbari Sahebari, Aidin. “Analysis of Idealized Numerical Simulations to Calibrate and Validate Boundary Layer Models
.” 2015. Web. 12 Apr 2021.
Vancouver:
Jabbari Sahebari A. Analysis of Idealized Numerical Simulations to Calibrate and Validate Boundary Layer Models
. [Internet] [Thesis]. Queens University; 2015. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/1974/13568.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Jabbari Sahebari A. Analysis of Idealized Numerical Simulations to Calibrate and Validate Boundary Layer Models
. [Thesis]. Queens University; 2015. Available from: http://hdl.handle.net/1974/13568
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Ottawa
26.
Fu, Jingyi J.Y.
Delay Analysis of Digital Circuits Using Prony's Method
.
Degree: 2011, University of Ottawa
URL: http://hdl.handle.net/10393/20125
► This thesis describes possible applications of Prony's method in timing analysis of digital circuits. Such applications include predicting the future shape of the waveform in…
(more)
▼ This thesis describes possible applications of Prony's method in timing analysis of digital circuits. Such applications include predicting the future shape of the waveform in DTA(Dynamic Timing Analysis) and delay look-up table in STA(Static Timing Analysis).
Given some equally spaced output values, the traditional Prony's method can be used to extract poles and residues of a linear system, i.e. to characterize a waveform using an exponential function. In this thesis, not only values but also equally spaced derivatives are tested. Still using same idea of the traditional Prony's method, poles and residues can also be extracted with those values and derivatives. The resultant poles and residues will be used to predict the output waveform in DTA analysis. The benefits brought by the using of derivatives include less simulation steps and less CPU time consuming than the regular constant step simulation.
As a matter of fact, the Prony's method can precisely approximate a complicated waveform. Such property can be applied for STA analysis. The Prony's approximation can be used to precisely record an output waveform, which is used as an entry of the look-up table of STA. Since the accuracy of STA analysis relies on the accuracy of the input and output waveform in the look-up table, the accuracy of the Prony's approach is promising.
Subjects/Keywords: Prony's method;
Timing Analysis;
Obreshokov;
numerical method;
Dynamic Timing Analysis (DTA);
Static Timing Analysis (STA)
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Manager
APA (6th Edition):
Fu, J. J. Y. (2011). Delay Analysis of Digital Circuits Using Prony's Method
. (Thesis). University of Ottawa. Retrieved from http://hdl.handle.net/10393/20125
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Fu, Jingyi J Y. “Delay Analysis of Digital Circuits Using Prony's Method
.” 2011. Thesis, University of Ottawa. Accessed April 12, 2021.
http://hdl.handle.net/10393/20125.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Fu, Jingyi J Y. “Delay Analysis of Digital Circuits Using Prony's Method
.” 2011. Web. 12 Apr 2021.
Vancouver:
Fu JJY. Delay Analysis of Digital Circuits Using Prony's Method
. [Internet] [Thesis]. University of Ottawa; 2011. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/10393/20125.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Fu JJY. Delay Analysis of Digital Circuits Using Prony's Method
. [Thesis]. University of Ottawa; 2011. Available from: http://hdl.handle.net/10393/20125
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
New Jersey Institute of Technology
27.
Ma, Manman.
A numerical method for electro-kinetic flow with deformable interfaces.
Degree: PhD, Mathematical Sciences, 2013, New Jersey Institute of Technology
URL: https://digitalcommons.njit.edu/dissertations/372
► We consider two-phase flow of ionic fluids whose motion is driven by an imposed electric field. At a fluid-fluid interface, a screening cloud of…
(more)
▼ We consider two-phase flow of ionic fluids whose motion is driven by an imposed electric field. At a fluid-fluid interface, a screening cloud of ions develops and forms an electro-chemical double layer or ‘Debye layer’. The applied electric field acts on the ionic cloud it induces, resulting in a strong slip flow near the interface. This is known as ‘induced-charge electro-kinetic flow’, and is an important phenomenon in microfluidic applications and in the manipulation of biological cells. The models with two different cases including the fast or slow charging time scales are studied both analytically and numerically. We address a significant challenge in the
numerical computation of such flows in the thin-double-layer limit, by using the slenderness of the layer to develop a fast and accurate ‘hybrid’ or multiscale
numerical method. The
method incorporates an asymptotic analysis of the electric potential and fluid dynamics in the Debye layer into a boundary integral
numerical solution of the full moving boundary problem.
We present solutions for the quasi-steady state problem with ψ = O(1) and solutions for the time dependent problem with ψ « 1, where ψ is the dimensionless surface potential. Leading order problems for both electric fields and fluid fields are solved with boundary conditions and matching methods. The small deformation theories when Ca is small (Ca is the electric capillary number) for both quasi-steady state and time dependent problems are developed to check
numerical simulations.
Advisors/Committee Members: Michael Siegel, Michael R. Booty, Linda Jane Cummings.
Subjects/Keywords: Electro-kinetics; Hybrid numerical method; Moving boundary problem; Asymptotics; Small deformation; Boundary integral method; Mathematics
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APA ·
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Manager
APA (6th Edition):
Ma, M. (2013). A numerical method for electro-kinetic flow with deformable interfaces. (Doctoral Dissertation). New Jersey Institute of Technology. Retrieved from https://digitalcommons.njit.edu/dissertations/372
Chicago Manual of Style (16th Edition):
Ma, Manman. “A numerical method for electro-kinetic flow with deformable interfaces.” 2013. Doctoral Dissertation, New Jersey Institute of Technology. Accessed April 12, 2021.
https://digitalcommons.njit.edu/dissertations/372.
MLA Handbook (7th Edition):
Ma, Manman. “A numerical method for electro-kinetic flow with deformable interfaces.” 2013. Web. 12 Apr 2021.
Vancouver:
Ma M. A numerical method for electro-kinetic flow with deformable interfaces. [Internet] [Doctoral dissertation]. New Jersey Institute of Technology; 2013. [cited 2021 Apr 12].
Available from: https://digitalcommons.njit.edu/dissertations/372.
Council of Science Editors:
Ma M. A numerical method for electro-kinetic flow with deformable interfaces. [Doctoral Dissertation]. New Jersey Institute of Technology; 2013. Available from: https://digitalcommons.njit.edu/dissertations/372
Univerzitet u Beogradu
28.
Džindo, Emina, 1973-.
Развој прслине заварених хетерогених спојева.
Degree: Mašinski fakultet, 2018, Univerzitet u Beogradu
URL: https://fedorabg.bg.ac.rs/fedora/get/o:19042/bdef:Content/get
► Област техничких наука, машинство - Технологија материјала, механика лома / technical science - materials and technology, fracture mechanics
Експериментално анализирање раста прслине у појединим конституентима…
(more)
▼ Област техничких наука, машинство - Технологија
материјала, механика лома / technical science - materials and
technology, fracture mechanics
Експериментално анализирање раста прслине у
појединим конституентима завареннх спојева комплексно легираннх
челика високе чврстоће на епруветама и у реалним конструкцијама,
као и утицај раста прслине на сигурност завареног споја управо је
циљ овог рада. Да би се омогуhило заваривање таквих конструкцијских
челика, додатни материјал за заваривање се пројектује тако да метал
шава након заваривања има нешто мању чврстоћу од основног метала
(андермечинг ефект). У тако завареном споју до пластичног течења ће
доћи прво у металу шава. Тек након ојачавања МШ до нивоа границе
течења ОМ долази до ппастичног деформисања ОМ. Циљ овог рада је да
се покажу нумерички модели, допринос анализи проблема из референтне
области који се састоји управо у могућности да се на брз и
релативно једноставан начин развоја модела који ће на меродаван
начин представити реално понашање епрувета,, у погледу
концентрације напона и поља деформацијатоком релевантних
оптерећења. Нумеричком анализом могуће је приказати и ширење
прслине, односно промена њене дужине у односу на иницијалну
вредност од 2.3 mm. Ови резултати се такође могу искористити и као
основа за будућа истраживања, која би могла да се баве испитивањем
понашања оваквих епрувета на заморно оптерећење, с обзиром да су
посуде под притиском (област примене оваквих материјала) управо
изложене оваквом оптерећењу и најчешће отказују услед истог. Дакле,
прво су примењене метода коначних елемената као нумеричка метода,
као и две експерименталне методе метода мерних трака и метода за
дигиталну корелацију слика. Детаљно је сакупљена, проучена и
систематизована научна литература из области везана за све аспекте
ове дисертације. Анализирана је разлика у понашању завареног споја
као целине и његових конституената и затезањем су испитане епрувете
са металом шава мање и веће чврстоће у односу на основни метал што
је важно и за оцену отпорности према ширењу прслине, даје основне
податке о понашању материјала при оптерећивању...
Advisors/Committee Members: Radaković, Zoran, 1961-.
Subjects/Keywords: heterogenous welded joint; undermatching; finite
element method; strength; numerical simulation; plastic
deformation; strain gauge method
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APA ·
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APA (6th Edition):
Džindo, Emina, 1. (2018). Развој прслине заварених хетерогених спојева. (Thesis). Univerzitet u Beogradu. Retrieved from https://fedorabg.bg.ac.rs/fedora/get/o:19042/bdef:Content/get
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Džindo, Emina, 1973-. “Развој прслине заварених хетерогених спојева.” 2018. Thesis, Univerzitet u Beogradu. Accessed April 12, 2021.
https://fedorabg.bg.ac.rs/fedora/get/o:19042/bdef:Content/get.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Džindo, Emina, 1973-. “Развој прслине заварених хетерогених спојева.” 2018. Web. 12 Apr 2021.
Vancouver:
Džindo, Emina 1. Развој прслине заварених хетерогених спојева. [Internet] [Thesis]. Univerzitet u Beogradu; 2018. [cited 2021 Apr 12].
Available from: https://fedorabg.bg.ac.rs/fedora/get/o:19042/bdef:Content/get.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Džindo, Emina 1. Развој прслине заварених хетерогених спојева. [Thesis]. Univerzitet u Beogradu; 2018. Available from: https://fedorabg.bg.ac.rs/fedora/get/o:19042/bdef:Content/get
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Delft University of Technology
29.
Papakrivopoulos, Vasilis (author).
Development and Preliminary Evaluation of the Main Features of the Particle Finite Element Method (PFEM) for Solid Mechanics.
Degree: 2018, Delft University of Technology
URL: http://resolver.tudelft.nl/uuid:f269c81c-0f10-4622-8b0f-0bf5bc2227a0
► The Particle Finite Element Method is a numerical tool that has been introduced more than a decade ago for the solution of engineering problems involving…
(more)
▼ The Particle Finite Element
Method is a
numerical tool that has been introduced more than a decade ago for the solution of engineering problems involving large deformations. The
method falls under the category of mesh-based particle methods, meaning that all information is stored on moving particles that represent the domain under analysis and a computational mesh is used for the solution of the governing equations. Although the
method was initially developed for simulating fluid\hyp{}structure interaction problems, owing to its versatility in handling large deformation and constant changes in domain boundaries and contact interfaces, it has been recently employed for solid mechanics applications. However, the lack of a consistent framework for this kind of problems has lead to different implementations of the
method presented in the literature, each with its own special features. The main objective of this thesis is to implement a variation of the Particle Finite Element
Method and investigate the efficiency of the different features available in literature. Initially, the meshing procedure of the
method was developed, which consists of a Delaunay triangulation for assessing the connectivity of the particles and the {α}-shape
method for detection of the boundaries of the different domains. This was followed by an investigation on the influence of the related parameter {α
lim} on the outcome of the analysis; it appears that this choice has an impact on the results, in terms of the recovered domain volumes and the simulation response; this parameter has to be selected with care, with respect to the nature of the examined problem. Volume variations are also observed, caused by element deletion and/or addition during remeshing, which, eventually, lead to mass oscillations. These effects can be mitigated by either adjusting the value of the {α
lim} parameter, refining the particle distribution or prescribing the boundary surface during remeshing, by using a constrained Delaunay triangulation. Another important feature of the PFEM is the treatment of contact, which is, typically, done in literature via employment of an interface mesh. This mesh is generated during remeshing, using the same scheme as for the regular domain meshes, i.e. a Delaunay triangulation and the {α}-shape
method, and the generated contact elements are then used to enforce the contact constraints, with a variety of methods. In this work, a simple algorithm that disallows inter-penetration and allows free separation and free movement perpendicular to the contact surfaces was formulated and validated against benchmark solid mechanics problems. The automatic contact detection and interface mesh generation allows for the incorporation of more advanced contact treatment schemes. Transference of information between successive meshes is important in PFEM for solid mechanics, especially when the history of elemental variables, e.g. stresses, is required for capturing the solid material…
Advisors/Committee Members: Vardon, Phil (mentor), Hicks, Michael (graduation committee), Pisano, Federico (graduation committee), Gonzalez Acosta, Leon (mentor), Delft University of Technology (degree granting institution).
Subjects/Keywords: Particle Finite Element Method; Numerical Modelling; Solid mechanics; Material Point Method; Remeshing
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APA (6th Edition):
Papakrivopoulos, V. (. (2018). Development and Preliminary Evaluation of the Main Features of the Particle Finite Element Method (PFEM) for Solid Mechanics. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:f269c81c-0f10-4622-8b0f-0bf5bc2227a0
Chicago Manual of Style (16th Edition):
Papakrivopoulos, Vasilis (author). “Development and Preliminary Evaluation of the Main Features of the Particle Finite Element Method (PFEM) for Solid Mechanics.” 2018. Masters Thesis, Delft University of Technology. Accessed April 12, 2021.
http://resolver.tudelft.nl/uuid:f269c81c-0f10-4622-8b0f-0bf5bc2227a0.
MLA Handbook (7th Edition):
Papakrivopoulos, Vasilis (author). “Development and Preliminary Evaluation of the Main Features of the Particle Finite Element Method (PFEM) for Solid Mechanics.” 2018. Web. 12 Apr 2021.
Vancouver:
Papakrivopoulos V(. Development and Preliminary Evaluation of the Main Features of the Particle Finite Element Method (PFEM) for Solid Mechanics. [Internet] [Masters thesis]. Delft University of Technology; 2018. [cited 2021 Apr 12].
Available from: http://resolver.tudelft.nl/uuid:f269c81c-0f10-4622-8b0f-0bf5bc2227a0.
Council of Science Editors:
Papakrivopoulos V(. Development and Preliminary Evaluation of the Main Features of the Particle Finite Element Method (PFEM) for Solid Mechanics. [Masters Thesis]. Delft University of Technology; 2018. Available from: http://resolver.tudelft.nl/uuid:f269c81c-0f10-4622-8b0f-0bf5bc2227a0
Princeton University
30.
Felker, Kyle Gerard.
High-order finite volume methods for magnetohydrodynamics with applications in computational astrophysics
.
Degree: PhD, 2019, Princeton University
URL: http://arks.princeton.edu/ark:/88435/dsp019k41zh43t
► Finite volume (FV) methods with high-order accuracy have attracted the interest of computational astrophysicists who are interested in modeling the most challenging physical regimes. With…
(more)
▼ Finite volume (FV) methods with high-order accuracy have attracted the interest of computational astrophysicists who are interested in modeling the most challenging physical regimes. With their large
numerical diffusivity, popular second-order accurate FV codes are incapable of resolving many such problems using current high-performance computing (HPC) hardware. High-order FV methods may perform more efficiently than their lower-order counterparts while continuing to offer the robust shock-capturing properties that are essential for simulating the highly compressible flows that often occur in astrophysical phenomena.
We present a novel fourth-order accurate finite volume
method for the solution of ideal magnetohydrodynamics (MHD). The
numerical method combines high-order quadrature rules in the solution to semi-discrete formulations of hyperbolic conservation laws with the upwind constrained transport (UCT) framework to ensure that the divergence-free constraint of the magnetic field is satisfied. A novel implementation of UCT that uses the piecewise parabolic
method (PPM) for the reconstruction of magnetic fields at cell corners in 2D is introduced. The resulting scheme can be expressed as the extension of the second-order accurate constrained transport (CT) Godunov-type scheme that is currently used in the Athena++ astrophysics code. After validating the base algorithm on a series of hydrodynamics test problems, we present the results of multidimensional MHD test problems which demonstrate formal fourth- order convergence for smooth problems, robustness for discontinuous problems, and improved accuracy relative to the second-order scheme.
The fourth-order FV
method is implemented within the open-source Athena++ framework. A comprehensive set of validation and performance tests are added and directly integrated in the collaborative development environment using continuous integration services. Other automated tools and practices are established to ensure the manageability of the codebase as it matures.
We apply the solver to a set of computationally demanding 2D benchmarks based on the Kelvin- Helmholtz instability. The fourth-order and several related high- order FV methods produce significantly more accurate solutions than the second-order
method. By comparing the computational performance of these schemes on modern multi-core, distributed-memory architectures, we show that the high-order solvers are capable of much greater efficiency (time- to-solution for a given level of accuracy) than the second-order alternatives.
Advisors/Committee Members: Stone, James M (advisor).
Subjects/Keywords: Finite volume method;
Godunov method;
Kelvin-Helmholtz instability;
Magnetohydrodynamics;
Numerical methods;
Software engineering
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APA ·
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Manager
APA (6th Edition):
Felker, K. G. (2019). High-order finite volume methods for magnetohydrodynamics with applications in computational astrophysics
. (Doctoral Dissertation). Princeton University. Retrieved from http://arks.princeton.edu/ark:/88435/dsp019k41zh43t
Chicago Manual of Style (16th Edition):
Felker, Kyle Gerard. “High-order finite volume methods for magnetohydrodynamics with applications in computational astrophysics
.” 2019. Doctoral Dissertation, Princeton University. Accessed April 12, 2021.
http://arks.princeton.edu/ark:/88435/dsp019k41zh43t.
MLA Handbook (7th Edition):
Felker, Kyle Gerard. “High-order finite volume methods for magnetohydrodynamics with applications in computational astrophysics
.” 2019. Web. 12 Apr 2021.
Vancouver:
Felker KG. High-order finite volume methods for magnetohydrodynamics with applications in computational astrophysics
. [Internet] [Doctoral dissertation]. Princeton University; 2019. [cited 2021 Apr 12].
Available from: http://arks.princeton.edu/ark:/88435/dsp019k41zh43t.
Council of Science Editors:
Felker KG. High-order finite volume methods for magnetohydrodynamics with applications in computational astrophysics
. [Doctoral Dissertation]. Princeton University; 2019. Available from: http://arks.princeton.edu/ark:/88435/dsp019k41zh43t
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. 
Open Access Theses and Dissertations
