subject:(Mesh AND Order Adaptation)

Virginia Tech

1. Choudhary, Aniruddha. Verification of Compressible and Incompressible Computational Fluid Dynamics Codes and Residual-based Mesh Adaptation.

Degree: PhD, Aerospace Engineering, 2015, Virginia Tech

URL: http://hdl.handle.net/10919/51169

► Code verification is the process of ensuring, to the degree possible, that there are no algorithm deficiencies and coding mistakes (bugs) in a scientific computing… (more)

▼ Code verification is the process of ensuring, to the degree possible, that there are no algorithm deficiencies and coding mistakes (bugs) in a scientific computing simulation. In this work, techniques are presented for performing code verification of boundary conditions commonly used in compressible and incompressible Computational Fluid Dynamics (CFD) codes. Using a compressible CFD code, this study assesses the subsonic inflow (isentropic and fixed-mass), subsonic outflow, supersonic outflow, no-slip wall (adiabatic and isothermal), and inviscid slip-wall. The use of simplified curved surfaces is proposed for easier generation of manufactured solutions during the verification of certain boundary conditions involving many constraints. To perform rigorous code verification, general grids with mixed cell types at the verified boundary are used. A novel approach is introduced to determine manufactured solutions for boundary condition verification when the velocity-field is constrained to be divergence-free during the simulation in an incompressible CFD code. Order of accuracy testing using the Method of Manufactured Solutions (MMS) is employed here for code verification of the major components of an open-source, multiphase flow code - MFIX. The presence of two-phase governing equations and a modified SIMPLE-based algorithm requiring divergence-free flows makes the selection of manufactured solutions more involved than for single-phase, compressible flows. Code verification is performed here on 2D and 3D, uniform and stretched meshes for incompressible, steady and unsteady, single-phase and two-phase flows using the two-fluid model of MFIX. In a CFD simulation, truncation error (TE) is the difference between the continuous governing equation and its discrete approximation. Since TE can be shown to be the local source term for the discretization error, TE is proposed as the criterion for determining which regions of the computational mesh should be refined/coarsened. For mesh modification, an error equidistribution strategy to perform r-refinement (i.e., mesh node relocation) is employed. This technique is applied to 1D and 2D inviscid flow problems where the exact (i.e., analytic) solution is available. For mesh adaptation based upon TE, about an order of magnitude improvement in discretization error levels is observed when compared with the uniform mesh. Advisors/Committee Members: Roy, Christopher John (committeechair), Xiao, Heng (committee member), Neu, Wayne L. (committee member), Tafti, Danesh K. (committee member).

Subjects/Keywords: Code verification; Order of accuracy; Method of manufactured solutions; Boundary conditions; Multiphase flows; Mesh adaptation; Truncation error

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APA (6^th Edition):

Choudhary, A. (2015). Verification of Compressible and Incompressible Computational Fluid Dynamics Codes and Residual-based Mesh Adaptation. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/51169

Chicago Manual of Style (16^th Edition):

Choudhary, Aniruddha. “Verification of Compressible and Incompressible Computational Fluid Dynamics Codes and Residual-based Mesh Adaptation.” 2015. Doctoral Dissertation, Virginia Tech. Accessed April 16, 2021. http://hdl.handle.net/10919/51169.

MLA Handbook (7^th Edition):

Choudhary, Aniruddha. “Verification of Compressible and Incompressible Computational Fluid Dynamics Codes and Residual-based Mesh Adaptation.” 2015. Web. 16 Apr 2021.

Vancouver:

Choudhary A. Verification of Compressible and Incompressible Computational Fluid Dynamics Codes and Residual-based Mesh Adaptation. [Internet] [Doctoral dissertation]. Virginia Tech; 2015. [cited 2021 Apr 16]. Available from: http://hdl.handle.net/10919/51169.

Council of Science Editors:

Choudhary A. Verification of Compressible and Incompressible Computational Fluid Dynamics Codes and Residual-based Mesh Adaptation. [Doctoral Dissertation]. Virginia Tech; 2015. Available from: http://hdl.handle.net/10919/51169

2. Viville, Quentin. A method of hp-adaptation for Residual Distribution schemes : Construction d’une méthode hp-adaptative pour les schémas aux Résidus Distribués.

Degree: Docteur es, Mathématiques appliquées et calcul scientifique, 2016, Bordeaux

URL: http://www.theses.fr/2016BORD0408

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Cette thèse présente la construction d’un schéma aux Résidus Distribués p-adaptatif pour la discrétisation des équations d’Euler ainsi qu’un schéma aux Résidus Distribués hp-adaptatif pour… (more)

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Cette thèse présente la construction d’un schéma aux Résidus Distribués p-adaptatif pour la discrétisation des équations d’Euler ainsi qu’un schéma aux Résidus Distribués hp-adaptatif pour les équations de Navier- Stokes pénalisées. On rappelle tout d’abord les équations d’Euler et de Navier-Stokes ainsi que leurs versions non dimensionnelles. Les définitions et propriétés de base des schémas aux Résidus Distribués sont ensuite présentées. On décrit alors la construction d’un schéma aux Résidus Distribués p-adaptatif pour les équations d’Euler. La construction du schéma p-adaptatif est basée sur la possibilité d’exprimer le résidu total d’un élément K de degré k (au sens où l’élément fini (K; P; Sigma ) est un élément fini de degré k) comme une somme pondérée des résidus totaux de ses sous-éléments de degré 1. La solution discrète ainsi obtenue est en général discontinue à l’interface entre un élément subdivisé et un élément non subdivisé. Ceci contredit l’hypothèse de continuité de la solution qui est utilisée pour démontrer le théorème de Lax-Wendroff discret pour les schémas aux Résidus Distribués. Cependant, on montre que cette hypothèse peut être assouplie. La conséquence pratique est que si l’on emploie des quadratures particulières dans l’implémentation numérique, on peut quand même démontrer le théorème de Lax-Wendroff discret, ce qui garantit la convergence du schéma numérique vers une solution faible des équations d’origine. Les formules qui permettent d’exprimer le résidu total comme une somme pondérée des résidus totaux des sous-éléments sont à la base de la méthode de p-adaptation présentée ici. Dans le cas quadratique, la formule est obtenue avec les classiques fonctions de base de Lagrange en dimension deux et avec des fonctions de base de Bézier en dimension trois. Ces deux formules sont ensuite généralisées à des degrés polynomiaux quelconques en dimension deux et trois avec des fonctions de base de Bézier. Dans la deuxième partie de la thèse, on présente l’application du schéma p-adaptatif aux équations pénalisées de Navier-Stokes avec adaptation de maillage anisotrope. . En pratique, on combine le schéma p-adaptatif avec la méthode IBM-LS-AUM (Immersed Boundary Method with Level Sets and Adapted Unstructured Meshes). La méthode IBM-LS-AUM permet d’imposer les conditions aux bords grâce à la méthode de pénalisation et l’adaptation anisotrope du maillage à la solution numérique et à la level-set augmente la précision de la solution et de la représentation de la surface. Une fois la méthode IBM-LS-AUM combinée avec le schéma p-adaptatif, il est alors possible d’utiliser des éléments d’ordre élevés en-dehors de la zone où la pénalisation est appliquée. La méthode est robuste comme le montrent les diverses expérimentations numériques à des vitesses faibles à élevées et à différents nombres de Reynolds.

This thesis presents the construction of a p-adaptive Residual Distribution scheme for the steady Euler equations and a hp-adaptive Residual Distribution scheme for the steady penalized Navier-Stokes…

Advisors/Committee Members: Abgrall, Rémi (thesis director), Beaugendre, Héloïse (thesis director).

Subjects/Keywords: Schémas aux Résidus Distribués; P-adaptation; Hp-adaptation; Adaptation de maillage anisotrope; Équations d’Euler; Équations de Navier-Stokes; Écoulements compressibles; Méthodes d’ordre élevé; Residual Distribution schemes; High-order methods; P-adaptation; Hp-adaptation; Anisotropic mesh adaptation; Euler equations; Navier-Stokes equations; Compressible flows

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

APA (6^th Edition):

Viville, Q. (2016). A method of hp-adaptation for Residual Distribution schemes : Construction d’une méthode hp-adaptative pour les schémas aux Résidus Distribués. (Doctoral Dissertation). Bordeaux. Retrieved from http://www.theses.fr/2016BORD0408

Chicago Manual of Style (16^th Edition):

Viville, Quentin. “A method of hp-adaptation for Residual Distribution schemes : Construction d’une méthode hp-adaptative pour les schémas aux Résidus Distribués.” 2016. Doctoral Dissertation, Bordeaux. Accessed April 16, 2021. http://www.theses.fr/2016BORD0408.

MLA Handbook (7^th Edition):

Viville, Quentin. “A method of hp-adaptation for Residual Distribution schemes : Construction d’une méthode hp-adaptative pour les schémas aux Résidus Distribués.” 2016. Web. 16 Apr 2021.

Vancouver:

Viville Q. A method of hp-adaptation for Residual Distribution schemes : Construction d’une méthode hp-adaptative pour les schémas aux Résidus Distribués. [Internet] [Doctoral dissertation]. Bordeaux; 2016. [cited 2021 Apr 16]. Available from: http://www.theses.fr/2016BORD0408.

Council of Science Editors:

Viville Q. A method of hp-adaptation for Residual Distribution schemes : Construction d’une méthode hp-adaptative pour les schémas aux Résidus Distribués. [Doctoral Dissertation]. Bordeaux; 2016. Available from: http://www.theses.fr/2016BORD0408

3. Feuillet, Rémi. Embedded and high-order meshes : two alternatives to linear body-fitted meshes : Maillages immergés et d'ordre élevé : deux alternatives à la représentation linéaire des maillages en géométrie inscrite.

Degree: Docteur es, Mathématiques appliquées, 2019, Université Paris-Saclay (ComUE)

URL: http://www.theses.fr/2019SACLY010

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La simulation numérique de phénomènes physiques complexes requiert généralement l’utilisation d’un maillage. En mécanique des fluides numérique, cela consisteà représenter un objet dans un gros… (more)

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La simulation numérique de phénomènes physiques complexes requiert généralement l’utilisation d’un maillage. En mécanique des fluides numérique, cela consisteà représenter un objet dans un gros volume de contrôle. Cet objet étant celui dont l’on souhaite simuler le comportement. Usuellement, l’objet et la boîte englobante sont représentés par des maillage de surface linéaires et la zone intermédiaire est remplie par un maillage volumique. L’objectif de cette thèse est de s’intéresser à deux manières différentes de représenter cet objet. La première approche dite immergée consiste à mailler intégralement le volume de contrôle et ensuite à simuler le comportement autour de l’objet sans avoir à mailler explicitement dans le volume ladite géometrie. L’objet étant implicitement pris en compte par le schéma numérique. Le couplage de cette méthode avec de l’adaptation de maillage linéaire est notamment étudié. La deuxième approche dite d’ordre élevé consiste quant à elle consiste à augmenter le degré polynomial du maillage de surface de l’objet. La première étape consiste donc à générer le maillage de surface de degré élevé et ensuite àpropager l’information de degré élevé dans les éléments volumiques environnants si nécessaire. Dans ce cadre-là, il s’agit de s’assurer de la validité de telles modifications et à considérer l’extension des méthodes classiques de modification de maillages linéaires.

The numerical simulation of complex physical phenomenons usually requires a mesh. In Computational Fluid Dynamics, it consists in representing an object inside a huge control volume. This object is then the subject of some physical study. In general, this object and its bounding box are represented by linear surface meshes and the intermediary zone is filled by a volume mesh. The aim of this thesis is to have a look on two different approaches for representing the object. The first approach called embedded method consist in integrally meshing the bounding box volume without explicitly meshing the object in it. In this case, the presence of the object is implicitly simulated by the CFD solver. The coupling of this method with linear mesh adaptation is in particular discussed.The second approach called high-order method consist on the contrary by increasing the polynomial order of the surface mesh of the object. The first step is therefore to generate a suitable high-order mesh and then to propagate the high-order information in the neighboring volume if necessary. In this context, it is mandatory to make sure that such modifications are valid and then the extension of classic mesh modification techniques has to be considered.

Advisors/Committee Members: Ciarlet, Patrick (thesis director), Alauzet, Frédéric (thesis director).

Subjects/Keywords: Méthodes d'ordre élevé; Visualisation scientifique; Méthodes immergées; Mécanique des fluides numérique; Adaptation de maillage; High-Order methods; Scientific visualization; Embedded methods; Cfd; Mesh adaptation

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

APA (6^th Edition):

Feuillet, R. (2019). Embedded and high-order meshes : two alternatives to linear body-fitted meshes : Maillages immergés et d'ordre élevé : deux alternatives à la représentation linéaire des maillages en géométrie inscrite. (Doctoral Dissertation). Université Paris-Saclay (ComUE). Retrieved from http://www.theses.fr/2019SACLY010

Chicago Manual of Style (16^th Edition):

Feuillet, Rémi. “Embedded and high-order meshes : two alternatives to linear body-fitted meshes : Maillages immergés et d'ordre élevé : deux alternatives à la représentation linéaire des maillages en géométrie inscrite.” 2019. Doctoral Dissertation, Université Paris-Saclay (ComUE). Accessed April 16, 2021. http://www.theses.fr/2019SACLY010.

MLA Handbook (7^th Edition):

Feuillet, Rémi. “Embedded and high-order meshes : two alternatives to linear body-fitted meshes : Maillages immergés et d'ordre élevé : deux alternatives à la représentation linéaire des maillages en géométrie inscrite.” 2019. Web. 16 Apr 2021.

Vancouver:

Feuillet R. Embedded and high-order meshes : two alternatives to linear body-fitted meshes : Maillages immergés et d'ordre élevé : deux alternatives à la représentation linéaire des maillages en géométrie inscrite. [Internet] [Doctoral dissertation]. Université Paris-Saclay (ComUE); 2019. [cited 2021 Apr 16]. Available from: http://www.theses.fr/2019SACLY010.

Council of Science Editors:

Feuillet R. Embedded and high-order meshes : two alternatives to linear body-fitted meshes : Maillages immergés et d'ordre élevé : deux alternatives à la représentation linéaire des maillages en géométrie inscrite. [Doctoral Dissertation]. Université Paris-Saclay (ComUE); 2019. Available from: http://www.theses.fr/2019SACLY010

University of California – Berkeley

4. Fortunato, Meire. Curved and anisotropic unstructured mesh generation and adaptivity using the Winslow equations.

Degree: Mathematics, 2016, University of California – Berkeley

URL: http://www.escholarship.org/uc/item/0zc4s5sv

► High-order methods are receiving considerable interest from the computational community because they can achieve higher accuracy with reduced computational cost compared to traditional low-order approaches.… (more)

Subjects/Keywords: Mathematics; High-order curved mesh adaptivity; High-order curved mesh generation; High-order methods

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APA (6^th Edition):

Fortunato, M. (2016). Curved and anisotropic unstructured mesh generation and adaptivity using the Winslow equations. (Thesis). University of California – Berkeley. Retrieved from http://www.escholarship.org/uc/item/0zc4s5sv

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Fortunato, Meire. “Curved and anisotropic unstructured mesh generation and adaptivity using the Winslow equations.” 2016. Thesis, University of California – Berkeley. Accessed April 16, 2021. http://www.escholarship.org/uc/item/0zc4s5sv.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Fortunato, Meire. “Curved and anisotropic unstructured mesh generation and adaptivity using the Winslow equations.” 2016. Web. 16 Apr 2021.

Vancouver:

Fortunato M. Curved and anisotropic unstructured mesh generation and adaptivity using the Winslow equations. [Internet] [Thesis]. University of California – Berkeley; 2016. [cited 2021 Apr 16]. Available from: http://www.escholarship.org/uc/item/0zc4s5sv.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Fortunato M. Curved and anisotropic unstructured mesh generation and adaptivity using the Winslow equations. [Thesis]. University of California – Berkeley; 2016. Available from: http://www.escholarship.org/uc/item/0zc4s5sv

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Illinois – Urbana-Champaign

5. Mittal, Ketan. Spectral element mesh generation and improvement methods.

Degree: MS, Mechanical Engineering, 2016, University of Illinois – Urbana-Champaign

URL: http://hdl.handle.net/2142/95509

► Meshing tools for finite element meshes have been studied extensively over the last few decades. However, relatively less attention has been paid to spectral element… (more)

▼ Meshing tools for finite element meshes have been studied extensively over the last few decades. However, relatively less attention has been paid to spectral element meshes. This thesis focuses on mesh generation and mesh improvement methods for spectral element meshes. A mesh smoother, based on a combination of Laplacian smoothing and optimization, has been developed and implemented in Nek5000, an open-source spectral element method based incompressible flow solver. The smoother takes a valid mesh as an input and outputs an improved mesh. Comparison of the original and smoothed mesh has shown that mesh smoothing decreases the iteration count of iterative solvers. This reduction is anticipated from an observed decrease in the ratio of the maximum to minimum eigenvalues of the upper Hessenberg matrix generated by the GMRES method. The mesh smoother was tested on various meshes for complicated geometries, and was found to improve the computational efficiency of calculations by up to 20% which is helping save 100,000s of cpu-hours on high-performance computing machines. A mesh skinning tool has also been developed which adds boundary layer resolving elements of user-specified thickness at user-specified surfaces in an existing mesh. This translates into savings in terms of human time and effort since the user can now robustly add boundary layer resolving elements instead of manually meshing the geometry to add these elements. Additionally, tools have been developed that generate meshes for geometries like turbine blades and random-array of cylinders (to simulate flow in vegetated channels), in a matter of seconds. Finally, a tetrahedral (tet) to hexahedron (hex) mesh converter has been implemented, that generates spectral element meshes for any complicated geometry by taking an all-tet mesh and converting it to an all-hex spectral element mesh. This tool has been developed to quickly generate all-hex meshes with minimal user intervention. Advisors/Committee Members: Fischer, Paul F (advisor).

Subjects/Keywords: spectral element; high order; mesh smoothing; mesh optimization; mesh generation; mesh quality; hexahedral mesh; quad mesh

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

APA (6^th Edition):

Mittal, K. (2016). Spectral element mesh generation and improvement methods. (Thesis). University of Illinois – Urbana-Champaign. Retrieved from http://hdl.handle.net/2142/95509

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Mittal, Ketan. “Spectral element mesh generation and improvement methods.” 2016. Thesis, University of Illinois – Urbana-Champaign. Accessed April 16, 2021. http://hdl.handle.net/2142/95509.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Mittal, Ketan. “Spectral element mesh generation and improvement methods.” 2016. Web. 16 Apr 2021.

Vancouver:

Mittal K. Spectral element mesh generation and improvement methods. [Internet] [Thesis]. University of Illinois – Urbana-Champaign; 2016. [cited 2021 Apr 16]. Available from: http://hdl.handle.net/2142/95509.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Mittal K. Spectral element mesh generation and improvement methods. [Thesis]. University of Illinois – Urbana-Champaign; 2016. Available from: http://hdl.handle.net/2142/95509

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

6. Wang, Yaqi. hp-mesh adaptation for 1-D multigroup neutron diffusion problems.

Degree: MS, Nuclear Engineering, 2007, Texas A&M University

URL: http://hdl.handle.net/1969.1/4707

► In this work, we propose, implement and test two fully automated mesh adaptation methods for 1-D multigroup eigenproblems. The first method is the standard hp-adaptive… (more)

Subjects/Keywords: hp-Mesh adaptation; Multigroup; Neutron diffusion; Multi-mesh; Finite element method; Higher order

…219 ix LIST OF FIGURES Page Fig. I-1. Schematics of mesh adaptation… …51 Fig. III-1. Schematics of mesh adaptation… …not be feasible without improved algorithms such as automatic mesh adaptation, where the… …mesh cells are automatically and selectively refined in order to reduce the largest… …large number of mesh points in order to represent accurately the spatial variation of the…

11 more images…

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

APA (6^th Edition):

Wang, Y. (2007). hp-mesh adaptation for 1-D multigroup neutron diffusion problems. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/4707

Chicago Manual of Style (16^th Edition):

Wang, Yaqi. “hp-mesh adaptation for 1-D multigroup neutron diffusion problems.” 2007. Masters Thesis, Texas A&M University. Accessed April 16, 2021. http://hdl.handle.net/1969.1/4707.

MLA Handbook (7^th Edition):

Wang, Yaqi. “hp-mesh adaptation for 1-D multigroup neutron diffusion problems.” 2007. Web. 16 Apr 2021.

Vancouver:

Wang Y. hp-mesh adaptation for 1-D multigroup neutron diffusion problems. [Internet] [Masters thesis]. Texas A&M University; 2007. [cited 2021 Apr 16]. Available from: http://hdl.handle.net/1969.1/4707.

Council of Science Editors:

Wang Y. hp-mesh adaptation for 1-D multigroup neutron diffusion problems. [Masters Thesis]. Texas A&M University; 2007. Available from: http://hdl.handle.net/1969.1/4707

7. Sanjaya, Devina. Towards Automated, Metric-Conforming, Mesh Optimization For High-Order, Finite-Element Methods.

Degree: PhD, Aerospace Engineering, 2019, University of Michigan

URL: http://hdl.handle.net/2027.42/151619

► High-resolution flow simulations are becoming important for increasingly many engineering applications. While high-resolution simulations give us the accuracy needed for engineering purposes, they generally demand… (more)

▼ High-resolution flow simulations are becoming important for increasingly many engineering applications. While high-resolution simulations give us the accuracy needed for engineering purposes, they generally demand high computational power and suitable meshes. Generating high-quality meshes itself is by no means a trivial problem. This dissertation presents a meshing algorithm that aims to eliminate the reliance on user’s experience, which has constantly compromised accuracy, created robustness issues, and caused difficulties in producing high-quality meshes. The novelty of our meshing algorithm lies in the optimal placement of the high-order geometry nodes within an element for more accurate and robust computational fluid dynamics (CFD) simulations. We first introduce a new mesh refinement method, called warped-element refinement (q adaptation), in which the high-order geometry nodes are automatically placed at their optimal locations given fixed locations of an element’s primary vertices. The benefits of this refinement method are demonstrated in an adaptive framework with a high-order, discontinuous Galerkin discretization and an a posteriori output error estimate. For fluid flows governed by the Euler, Navier-Stokes, and Reynolds-Averaged Navier-Stokes equations, for example, the drag output error can be reduced by at least a factor of two compared to the initial h-adapted mesh without adding much computational cost and software complexity. The optimal placement of the high-order geometry nodes also opens up the possibility of using coarser meshes with a high-order discretization. In order to better couple the optimal placement of an element’s vertices and its high- order geometry nodes, we turn to a Riemannian metric field to encode the mesh resolution. The three key steps in this process are: 1) obtain the desired higher-order, Riemannian metric field, 2) generate a linear, metric-conforming mesh, and 3) place the high-order geometry nodes such that the mesh-implied metric conforms to the desired metric field. We propose two methods to obtain a higher-order metric field and explore several metric-based mesh generation procedures for one-dimensional problems. Preliminary two-dimensional results further emphasize the importance of the high-order geometry nodes. These findings serve as fundamental knowledge for building a high-order, metric-conforming mesh generator in the future. Advisors/Committee Members: Fidkowski, Krzysztof J (committee member), Johnsen, Eric (committee member), Martins, Joaquim R R A (committee member), Murman, Scott M. (committee member), Nemec, Marian (committee member).

Subjects/Keywords: computational fluid dyanmics; metric-based mesh adaptation; high-order mesh; high-order metric field; high-order, metric-conforming mesh; warped-element refinement method; Aerospace Engineering; Engineering

…High-order mesh generation . . . . . . . . . . . . . . . . . . . 3.4.1 Local mesh… …4.3 Warping high-order mesh elements . . . . . . . . 4.4 Significance of high-order geometry… …single, high-order mesh element . . . . 6.2 Predicting an output of interest… …Illustration of node averaging at shared high-order geometry nodes following the local mesh… …mesh for use with high-order methods. . . . . . . . . . . . 55 ix 4.2 4.3 4.4 4.5 4.6…

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

APA (6^th Edition):

Sanjaya, D. (2019). Towards Automated, Metric-Conforming, Mesh Optimization For High-Order, Finite-Element Methods. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/151619

Chicago Manual of Style (16^th Edition):

Sanjaya, Devina. “Towards Automated, Metric-Conforming, Mesh Optimization For High-Order, Finite-Element Methods.” 2019. Doctoral Dissertation, University of Michigan. Accessed April 16, 2021. http://hdl.handle.net/2027.42/151619.

MLA Handbook (7^th Edition):

Sanjaya, Devina. “Towards Automated, Metric-Conforming, Mesh Optimization For High-Order, Finite-Element Methods.” 2019. Web. 16 Apr 2021.

Vancouver:

Sanjaya D. Towards Automated, Metric-Conforming, Mesh Optimization For High-Order, Finite-Element Methods. [Internet] [Doctoral dissertation]. University of Michigan; 2019. [cited 2021 Apr 16]. Available from: http://hdl.handle.net/2027.42/151619.

Council of Science Editors:

Sanjaya D. Towards Automated, Metric-Conforming, Mesh Optimization For High-Order, Finite-Element Methods. [Doctoral Dissertation]. University of Michigan; 2019. Available from: http://hdl.handle.net/2027.42/151619

Université de Bordeaux I

8. Froehly, Algiane. Couplage d’un schéma aux résidus distribués à l’analyse isogéométrique : méthode numérique et outils de génération et adaptation de maillage : Numerical methods for piecewise-deterministic Markov processes.

Degree: Docteur es, Mathématiques appliquées, 2012, Université de Bordeaux I

URL: http://www.theses.fr/2012BOR14563

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Lors de simulations numériques d’ordre élevé, la discrétisation sous-paramétrique du domaine de calcul peut générer des erreurs dominant l’erreur liée à la discrétisation des variables.… (more)

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Lors de simulations numériques d’ordre élevé, la discrétisation sous-paramétrique du domaine de calcul peut générer des erreurs dominant l’erreur liée à la discrétisation des variables. De nombreux travaux proposent d’utiliser l’analyse isogéométrique afin de mieux représenter les géométries et de résoudre ce problème.Nous présenterons dans ce travail le couplage du schéma aux résidus distribués limité et stabilisé de Lax-Frieirichs avec l’analyse isogéométrique. En particulier, nous construirons une famille de fonctions de base permettant de représenter exactement les coniques et définies tant sur les éléments triangulaires que quadrangulaires : les fonctions de base de Bernstein rationnelles. Nous nous intéresserons ensuite à la génération de maillages précis pour l’analyse isogéométrique. Notre méthode consiste à créer un maillage courbe à partir d’un maillage linéaire par morceaux de la géométrie. Le maillage obtenu en sortie de notre procédure est non-structuré, conforme et assure la continuité de nos fonctions de base sur tout le domaine. Pour finir, nous décrirons les différentes méthodes d’adaptation de maillages développées : l’élévation d’ordre et le raffinement isotrope. Bien évidemment, la géométrie exacte du maillage courbe d’entrée est préservée au cours des processus d’adaptation.

During high order simulations, the approximation error may be dominated by the errors linked to the sub-parametric discretization used for the geometry representation. Many works propose to use an isogeometric analysis approach to better represent the geometry and hence solve this problem. In this work, we will present the coupling between the limited stabilized Lax-Friedrichs residual distributed scheme and the isogeometric analysis. Especially, we will build a family of basis functions defined on both triangular and quadrangular elements and allowing the exact representation of conics : the rational Bernstein basis functions. We will then focus in how to generate accurate meshes for isogeometric analysis. Our idea is to create a curved mesh from a classical piecewise-linear mesh of the geometry. We obtain a conforming unstructured mesh which ensures the continuity of the basis functions over the entire mesh. Last, we will detail the curved mesh adaptation methods developed : the order elevation and the isotropic mesh refinement. Of course, the adaptation processes preserve the exact geometry of the initial curved mesh.

Advisors/Committee Members: Abgrall, Rémi (thesis director), Dobrzynski, Cécile (thesis director).

Subjects/Keywords: Équations d’Euler; Schéma aux Résidus Distribués; Ordre Très Élevé; Analyse Isogéométrique; Fonctions de Base NURBS; Fonctions de Base de Bernstein Rationnelles; Génération de Maillages Courbes; Adaptation de Maillages Courbes; H-raffinement; P-raffinement; Euler Equations; Residual Distribution Scheme; Very High Order; Isogeometric Analysis; Nurbs; Rational Bernstein Basis Functions; Curved Mesh Generation; Curved Mesh Adaptation; H-refinement; P-refinement

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APA (6^th Edition):

Froehly, A. (2012). Couplage d’un schéma aux résidus distribués à l’analyse isogéométrique : méthode numérique et outils de génération et adaptation de maillage : Numerical methods for piecewise-deterministic Markov processes. (Doctoral Dissertation). Université de Bordeaux I. Retrieved from http://www.theses.fr/2012BOR14563

Chicago Manual of Style (16^th Edition):

Froehly, Algiane. “Couplage d’un schéma aux résidus distribués à l’analyse isogéométrique : méthode numérique et outils de génération et adaptation de maillage : Numerical methods for piecewise-deterministic Markov processes.” 2012. Doctoral Dissertation, Université de Bordeaux I. Accessed April 16, 2021. http://www.theses.fr/2012BOR14563.

MLA Handbook (7^th Edition):

Froehly, Algiane. “Couplage d’un schéma aux résidus distribués à l’analyse isogéométrique : méthode numérique et outils de génération et adaptation de maillage : Numerical methods for piecewise-deterministic Markov processes.” 2012. Web. 16 Apr 2021.

Vancouver:

Froehly A. Couplage d’un schéma aux résidus distribués à l’analyse isogéométrique : méthode numérique et outils de génération et adaptation de maillage : Numerical methods for piecewise-deterministic Markov processes. [Internet] [Doctoral dissertation]. Université de Bordeaux I; 2012. [cited 2021 Apr 16]. Available from: http://www.theses.fr/2012BOR14563.

Council of Science Editors:

Froehly A. Couplage d’un schéma aux résidus distribués à l’analyse isogéométrique : méthode numérique et outils de génération et adaptation de maillage : Numerical methods for piecewise-deterministic Markov processes. [Doctoral Dissertation]. Université de Bordeaux I; 2012. Available from: http://www.theses.fr/2012BOR14563

University of Colorado

9. Engvall, Luke H. Geometrically Exact and Analysis Suitable Mesh Generation Using Rational Bernstein–Bezier Elements.

Degree: PhD, 2018, University of Colorado

URL: https://scholar.colorado.edu/mcen_gradetds/170

► This dissertation presents two novel contributions to the fields of isogeometric analysis and p-version finite elements. First, we present a framework for geometrically exact… (more)

Subjects/Keywords: curvilinear mesh generation; higher-order finite elements; isogeometric analysis; mesh generation; discretization; Engineering; Mechanical Engineering

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APA (6^th Edition):

Engvall, L. H. (2018). Geometrically Exact and Analysis Suitable Mesh Generation Using Rational Bernstein–Bezier Elements. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/mcen_gradetds/170

Chicago Manual of Style (16^th Edition):

Engvall, Luke H. “Geometrically Exact and Analysis Suitable Mesh Generation Using Rational Bernstein–Bezier Elements.” 2018. Doctoral Dissertation, University of Colorado. Accessed April 16, 2021. https://scholar.colorado.edu/mcen_gradetds/170.

MLA Handbook (7^th Edition):

Engvall, Luke H. “Geometrically Exact and Analysis Suitable Mesh Generation Using Rational Bernstein–Bezier Elements.” 2018. Web. 16 Apr 2021.

Vancouver:

Engvall LH. Geometrically Exact and Analysis Suitable Mesh Generation Using Rational Bernstein–Bezier Elements. [Internet] [Doctoral dissertation]. University of Colorado; 2018. [cited 2021 Apr 16]. Available from: https://scholar.colorado.edu/mcen_gradetds/170.

Council of Science Editors:

Engvall LH. Geometrically Exact and Analysis Suitable Mesh Generation Using Rational Bernstein–Bezier Elements. [Doctoral Dissertation]. University of Colorado; 2018. Available from: https://scholar.colorado.edu/mcen_gradetds/170

10. Dahm, Johann. Toward Accurate, Efficient, and Robust Hybridized Discontinuous Galerkin Methods.

Degree: PhD, Aerospace Engineering, 2017, University of Michigan

URL: http://hdl.handle.net/2027.42/137150

► Computational science, including computational fluid dynamics (CFD), has become an indispensible tool for scientific discovery and engineering design, yet a key remaining challenge is to… (more)

▼ Computational science, including computational fluid dynamics (CFD), has become an indispensible tool for scientific discovery and engineering design, yet a key remaining challenge is to simultaneously ensure accuracy, efficiency, and robustness of the calculations. This research focuses on advancing a class of high-order finite element methods and develops a set of algorithms to increase the accuracy, efficiency, and robustness of calculations involving convection and diffusion, with application to the inviscid Euler and viscous Navier-Stokes equations. In particular, it addresses high-order discontinuous Galerkin (DG) methods, especially hybridized (HDG) methods, and develops adjoint-based methods for simultaneous mesh and order adaptation to reduce the error in a scalar functional of the approximate solution to the discretized equations. Contributions are made in key aspects of these methods applied to general systems of equations, addressing the scalability and memory requirements, accuracy of HDG methods, and efficiency and robustness with new adaptation methods. First, this work generalizes existing HDG methods to systems of equations, and in so doing creates a new primal formulation by applying DG stabilization methods as the viscous stabilization for HDG. The primal formulation is shown to be even more computationally efficient than the existing methods. Second, by instead keeping existing viscous stabilization methods and developing a new convection stabilization, this work shows that additional accuracy can be obtained, even in the case of purely convective systems. Both HDG methods are compared to DG in the same computational framework and are shown to be more efficient. Finally, the set of adaptation frameworks is developed for combined mesh and order refinement suitable for both DG and HDG discretizations. The first of these frameworks uses hanging-node-based mesh adaptation and develops a novel local approach for evaluating the refinement options. The second framework intended for simplex meshes extends the mesh optimization via error sampling and synthesis (MOESS) method to incorporate order adaptation. Collectively, the results from this research address a number of key issues that currently are at the forefront of high-order CFD methods, and particularly to output-based hp-adaptation for DG and HDG methods. Advisors/Committee Members: Fidkowski, Krzysztof J (committee member), Krasny, Robert (committee member), May, Georg (committee member), Powell, Ken (committee member).

Subjects/Keywords: Computational Fluid Dynamics; High-Order Methods; Discontinous Galerkin Methods; Adjoint-Based Error Estimation; Mesh and Order Adaptation; Aerospace Engineering; Engineering

…degrees of freedom for MOESS-P, compared to order-only adaptation with a static mesh beginning… …mesh adaptation, in which the mesh size h is locally reduced for a given order p to obtain… …memory for routine use. • Coupling mesh (h) and order (p) adaptation in a… …changing the local size of the mesh elements (h-adaptation), the local polynomial order… …General solution procedure when using an error estimation and mesh adaptation process for a…

10 more images…

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APA (6^th Edition):

Dahm, J. (2017). Toward Accurate, Efficient, and Robust Hybridized Discontinuous Galerkin Methods. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/137150

Chicago Manual of Style (16^th Edition):

Dahm, Johann. “Toward Accurate, Efficient, and Robust Hybridized Discontinuous Galerkin Methods.” 2017. Doctoral Dissertation, University of Michigan. Accessed April 16, 2021. http://hdl.handle.net/2027.42/137150.

MLA Handbook (7^th Edition):

Dahm, Johann. “Toward Accurate, Efficient, and Robust Hybridized Discontinuous Galerkin Methods.” 2017. Web. 16 Apr 2021.

Vancouver:

Dahm J. Toward Accurate, Efficient, and Robust Hybridized Discontinuous Galerkin Methods. [Internet] [Doctoral dissertation]. University of Michigan; 2017. [cited 2021 Apr 16]. Available from: http://hdl.handle.net/2027.42/137150.

Council of Science Editors:

Dahm J. Toward Accurate, Efficient, and Robust Hybridized Discontinuous Galerkin Methods. [Doctoral Dissertation]. University of Michigan; 2017. Available from: http://hdl.handle.net/2027.42/137150

11. Xu, Jing. Automatic Linear and Curvilinear Mesh Generation Driven by Validity Fidelity and Topological Guarantees.

Degree: PhD, Computer Science, 2020, Old Dominion University

URL: 9798678109002 ; https://digitalcommons.odu.edu/computerscience_etds/127

► Image-based geometric modeling and mesh generation play a critical role in computational biology and medicine. In this dissertation, a comprehensive computational framework for both… (more)

Subjects/Keywords: Curvilinear; Fidelity; High-order; Homeomorphism; Mesh generation; Tetrahedralization; Computer Sciences

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APA (6^th Edition):

Xu, J. (2020). Automatic Linear and Curvilinear Mesh Generation Driven by Validity Fidelity and Topological Guarantees. (Doctoral Dissertation). Old Dominion University. Retrieved from 9798678109002 ; https://digitalcommons.odu.edu/computerscience_etds/127

Chicago Manual of Style (16^th Edition):

Xu, Jing. “Automatic Linear and Curvilinear Mesh Generation Driven by Validity Fidelity and Topological Guarantees.” 2020. Doctoral Dissertation, Old Dominion University. Accessed April 16, 2021. 9798678109002 ; https://digitalcommons.odu.edu/computerscience_etds/127.

MLA Handbook (7^th Edition):

Xu, Jing. “Automatic Linear and Curvilinear Mesh Generation Driven by Validity Fidelity and Topological Guarantees.” 2020. Web. 16 Apr 2021.

Vancouver:

Xu J. Automatic Linear and Curvilinear Mesh Generation Driven by Validity Fidelity and Topological Guarantees. [Internet] [Doctoral dissertation]. Old Dominion University; 2020. [cited 2021 Apr 16]. Available from: 9798678109002 ; https://digitalcommons.odu.edu/computerscience_etds/127.

Council of Science Editors:

Xu J. Automatic Linear and Curvilinear Mesh Generation Driven by Validity Fidelity and Topological Guarantees. [Doctoral Dissertation]. Old Dominion University; 2020. Available from: 9798678109002 ; https://digitalcommons.odu.edu/computerscience_etds/127

University of Toronto

12. Ivan, Lucian. Development of High-order CENO Finite-volume Schemes with Block-based Adaptive Mesh Refinement (AMR).

Degree: 2011, University of Toronto

URL: http://hdl.handle.net/1807/29759

►

A high-order central essentially non-oscillatory (CENO) finite-volume scheme in combination with a block-based adaptive mesh refinement (AMR) algorithm is proposed for solution of hyperbolic and… (more)

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A high-order central essentially non-oscillatory (CENO) finite-volume scheme in combination with a block-based adaptive mesh refinement (AMR) algorithm is proposed for solution of hyperbolic and elliptic systems of conservation laws on body- fitted multi-block mesh. The spatial discretization of the hyperbolic (inviscid) terms is based on a hybrid solution reconstruction procedure that combines an unlimited high-order k-exact least-squares reconstruction technique following from a fixed central stencil with a monotonicity preserving limited piecewise linear reconstruction algorithm. The limited reconstruction is applied to computational cells with under-resolved solution content and the unlimited k-exact reconstruction procedure is used for cells in which the solution is fully resolved. Switching in the hybrid procedure is determined by a solution smoothness indicator. The hybrid approach avoids the complexity associated with other ENO schemes that require reconstruction on multiple stencils and therefore, would seem very well suited for extension to unstructured meshes. The high-order elliptic (viscous) fluxes are computed based on a k-order accurate average gradient derived from a (k+1)-order accurate reconstruction. A novel h-refinement criterion based on the solution smoothness indicator is used to direct the steady and unsteady refinement of the AMR mesh. The predictive capabilities of the proposed high-order AMR scheme are demonstrated for the Euler and Navier-Stokes equations governing two-dimensional compressible gaseous flows as well as for advection-diffusion problems characterized by the full range of Peclet numbers, Pe. The ability of the scheme to accurately represent solutions with smooth extrema and yet robustly handle under-resolved and/or non-smooth solution content (i.e., shocks and other discontinuities) is shown for a range of problems. Moreover, the ability to perform mesh refinement in regions of smooth but under-resolved and/or non-smooth solution content to achieve the desired resolution is also demonstrated.

PhD

Advisors/Committee Members: Groth, Clinton P. T., Aerospace Science and Engineering.

Subjects/Keywords: computational fluid dynamics; finite-volume method; high-order scheme; adaptive mesh refinement (AMR); ENO scheme; essentially non-oscillatory; CENO; body-fitted multi-block mesh; high-order spatial discretization; numerical method; hyperbolic and elliptic PDE; fixed stencil reconstruction; piecewise linear reconstruction; smoothness indicator; Euler and Navier-Stokes equations; advection-diffusion equation; smooth and non-smooth solution content; k-exact least-squares reconstruction; hybrid numerical scheme; compressible gaseous flows; refinement criteria; high-performance parallel computing; solution monotonicity enforcement; large-eddy simulation (LES); interpolation technique; structured grid; inviscid and viscous flow; TVD scheme; h-p-adaptation; high-order boundary conditions; complex curved geometries; 0538

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APA (6^th Edition):

Ivan, L. (2011). Development of High-order CENO Finite-volume Schemes with Block-based Adaptive Mesh Refinement (AMR). (Doctoral Dissertation). University of Toronto. Retrieved from http://hdl.handle.net/1807/29759

Chicago Manual of Style (16^th Edition):

Ivan, Lucian. “Development of High-order CENO Finite-volume Schemes with Block-based Adaptive Mesh Refinement (AMR).” 2011. Doctoral Dissertation, University of Toronto. Accessed April 16, 2021. http://hdl.handle.net/1807/29759.

MLA Handbook (7^th Edition):

Ivan, Lucian. “Development of High-order CENO Finite-volume Schemes with Block-based Adaptive Mesh Refinement (AMR).” 2011. Web. 16 Apr 2021.

Vancouver:

Ivan L. Development of High-order CENO Finite-volume Schemes with Block-based Adaptive Mesh Refinement (AMR). [Internet] [Doctoral dissertation]. University of Toronto; 2011. [cited 2021 Apr 16]. Available from: http://hdl.handle.net/1807/29759.

Council of Science Editors:

Ivan L. Development of High-order CENO Finite-volume Schemes with Block-based Adaptive Mesh Refinement (AMR). [Doctoral Dissertation]. University of Toronto; 2011. Available from: http://hdl.handle.net/1807/29759

University of Pretoria

13. [No author]. Reduced order modeling techniques for mesh movement as applied to fluid structure interactions .

Degree: 2010, University of Pretoria

URL: http://upetd.up.ac.za/thesis/available/etd-08112010-143616/

► In this thesis, the method of Proper Orthogonal Decomposition (POD) is implemented to construct approximate, reduced order models (ROM) of mesh movement methods. Three mesh… (more)

Subjects/Keywords: Unstructured mesh movement; Mesh optimization; Proper orthogonal decomposition; Radial basis function interpolation; Reduced order modeling; Elastic deformation; UCTD

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APA (6^th Edition):

author], [. (2010). Reduced order modeling techniques for mesh movement as applied to fluid structure interactions . (Masters Thesis). University of Pretoria. Retrieved from http://upetd.up.ac.za/thesis/available/etd-08112010-143616/

Chicago Manual of Style (16^th Edition):

author], [No. “Reduced order modeling techniques for mesh movement as applied to fluid structure interactions .” 2010. Masters Thesis, University of Pretoria. Accessed April 16, 2021. http://upetd.up.ac.za/thesis/available/etd-08112010-143616/.

MLA Handbook (7^th Edition):

author], [No. “Reduced order modeling techniques for mesh movement as applied to fluid structure interactions .” 2010. Web. 16 Apr 2021.

Vancouver:

author] [. Reduced order modeling techniques for mesh movement as applied to fluid structure interactions . [Internet] [Masters thesis]. University of Pretoria; 2010. [cited 2021 Apr 16]. Available from: http://upetd.up.ac.za/thesis/available/etd-08112010-143616/.

Council of Science Editors:

author] [. Reduced order modeling techniques for mesh movement as applied to fluid structure interactions . [Masters Thesis]. University of Pretoria; 2010. Available from: http://upetd.up.ac.za/thesis/available/etd-08112010-143616/

University of Pretoria

14. Bogaers, Alfred Edward Jules. Reduced order modeling techniques for mesh movement as applied to fluid structure interactions.

Degree: Mechanical and Aeronautical Engineering, 2010, University of Pretoria

URL: http://hdl.handle.net/2263/27154

► In this thesis, the method of Proper Orthogonal Decomposition (POD) is implemented to construct approximate, reduced order models (ROM) of mesh movement methods. Three mesh… (more)

Subjects/Keywords: Unstructured mesh movement; Mesh optimization; Proper orthogonal decomposition; Radial basis function interpolation; Reduced order modeling; Elastic deformation; UCTD

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APA (6^th Edition):

Bogaers, A. E. (2010). Reduced order modeling techniques for mesh movement as applied to fluid structure interactions. (Masters Thesis). University of Pretoria. Retrieved from http://hdl.handle.net/2263/27154

Chicago Manual of Style (16^th Edition):

Bogaers, Alfred Edward. “Reduced order modeling techniques for mesh movement as applied to fluid structure interactions.” 2010. Masters Thesis, University of Pretoria. Accessed April 16, 2021. http://hdl.handle.net/2263/27154.

MLA Handbook (7^th Edition):

Bogaers, Alfred Edward. “Reduced order modeling techniques for mesh movement as applied to fluid structure interactions.” 2010. Web. 16 Apr 2021.

Vancouver:

Bogaers AE. Reduced order modeling techniques for mesh movement as applied to fluid structure interactions. [Internet] [Masters thesis]. University of Pretoria; 2010. [cited 2021 Apr 16]. Available from: http://hdl.handle.net/2263/27154.

Council of Science Editors:

Bogaers AE. Reduced order modeling techniques for mesh movement as applied to fluid structure interactions. [Masters Thesis]. University of Pretoria; 2010. Available from: http://hdl.handle.net/2263/27154

Penn State University

15. Clifford, Ivor David. A hybrid coarse and fine mesh solution method for prismatic high temperature gas-cooled reactor thermal-fluid analysis.

Degree: 2013, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/17633

► Evaluations of the fluid flow and heat transfer in prismatic high temperature gas-cooled reactors (HTGRs) are critical to ensuring the safety of designs. It is… (more)

▼ Evaluations of the fluid flow and heat transfer in prismatic high temperature gas-cooled reactors (HTGRs) are critical to ensuring the safety of designs. It is in this area that many uncertainties are found. The current generation of full-core prismatic HTGR safety analysis codes employ coarse mesh solution methods for modeling the fluid flow and heat transfer in this reactor. There is, however, no generally accepted procedure for deriving accurate coarse mesh parameters, and the assumptions and approximations made in deriving models for the subscale behavior vary significantly. In contrast, current full-core neutronics analysis methods employ detailed unit cell calculations, combined with formal mathematical homogenization techniques, to obtain consistent and accurate coarse mesh parameters. The resulting coarse mesh solutions are of high quality and accuracy, and the ability to reconstruct the fine scale solution is an inherent part of the approach. In this work a new approach to modeling HTGR thermal-fluids is proposed that combines concepts from modern CFD techniques, formal mathematical homogenization, and full-core neutronics analysis methods. In an attempt to bridge the gap between the current generation of coarse mesh methods and high resolution CFD approaches, a hybrid coarse/fine mesh compressible CFD solution scheme, intended for the safety analysis of prismatic HTGRs, has been developed. The reactor is considered on any scale to consist of a two-phase mixture of fluid and stationary solid components. This solution scheme is accompanied by a new model for the turbulent mixing and thermal dispersion in porous media based in the k-ε turbulence model. A new hierarchical solution scheme for modeling solid heat conduction is proposed which combines concepts from the equivalence theory in neutron transport and the field of reduced order modeling. Detailed unit cell calculations are used to obtain homogenized coarse mesh parameters and reduced order models are employed in modeling the time-dependent fine scale behavior. Inherent in this new approach is the ability to reconstruct the solution at any spatial scale. Coupled solutions based on the MHTGR-350MW benchmark are provided, demonstrating the features of the proposed methods. In particular the level of detail that is achieved by reconstructing the fine scale solution is far beyond that of traditional coarse mesh methods. The proposed methods are equally valid for other engineering applications, specifically those characterized by multiple spatial scales with complex flows through domains containing multiple arbitrary porous regions with localized heat sources and sinks. Advisors/Committee Members: Kostadin Nikolov Ivanov, Dissertation Advisor/Co-Advisor, Kostadin Nikolov Ivanov, Committee Chair/Co-Chair, Maria Nikolova Avramova, Committee Chair/Co-Chair, Fan Bill B Cheung, Committee Member, Robert Francis Kunz, Committee Member, Hrvoje Jasak, Special Member, Richard Martineau, Special Member, Onno Ubbink, Special Member.

Subjects/Keywords: prismatic HTGR; thermal-fluids; heat transfer; homogenization; multiscale; coarse mesh CFD; reduced order model

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APA (6^th Edition):

Clifford, I. D. (2013). A hybrid coarse and fine mesh solution method for prismatic high temperature gas-cooled reactor thermal-fluid analysis. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/17633

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Clifford, Ivor David. “A hybrid coarse and fine mesh solution method for prismatic high temperature gas-cooled reactor thermal-fluid analysis.” 2013. Thesis, Penn State University. Accessed April 16, 2021. https://submit-etda.libraries.psu.edu/catalog/17633.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Clifford, Ivor David. “A hybrid coarse and fine mesh solution method for prismatic high temperature gas-cooled reactor thermal-fluid analysis.” 2013. Web. 16 Apr 2021.

Vancouver:

Clifford ID. A hybrid coarse and fine mesh solution method for prismatic high temperature gas-cooled reactor thermal-fluid analysis. [Internet] [Thesis]. Penn State University; 2013. [cited 2021 Apr 16]. Available from: https://submit-etda.libraries.psu.edu/catalog/17633.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Clifford ID. A hybrid coarse and fine mesh solution method for prismatic high temperature gas-cooled reactor thermal-fluid analysis. [Thesis]. Penn State University; 2013. Available from: https://submit-etda.libraries.psu.edu/catalog/17633

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Toronto

16. McDonald, Sean D. Development of a High-order Finite-volume Method for Unstructured Meshes.

Degree: 2011, University of Toronto

URL: http://hdl.handle.net/1807/29528

►

The development of high-order solution methods remain a very active field of research in Computational Fluid Dynamics (CFD). These types of schemes have the potential… (more)

Subjects/Keywords: Computational Fluid Dynamics; High-Order; Central Essentially Non-Oscillatory; Unstructured Mesh; Fluid Dynamics; 0538

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APA (6^th Edition):

McDonald, S. D. (2011). Development of a High-order Finite-volume Method for Unstructured Meshes. (Masters Thesis). University of Toronto. Retrieved from http://hdl.handle.net/1807/29528

Chicago Manual of Style (16^th Edition):

McDonald, Sean D. “Development of a High-order Finite-volume Method for Unstructured Meshes.” 2011. Masters Thesis, University of Toronto. Accessed April 16, 2021. http://hdl.handle.net/1807/29528.

MLA Handbook (7^th Edition):

McDonald, Sean D. “Development of a High-order Finite-volume Method for Unstructured Meshes.” 2011. Web. 16 Apr 2021.

Vancouver:

McDonald SD. Development of a High-order Finite-volume Method for Unstructured Meshes. [Internet] [Masters thesis]. University of Toronto; 2011. [cited 2021 Apr 16]. Available from: http://hdl.handle.net/1807/29528.

Council of Science Editors:

McDonald SD. Development of a High-order Finite-volume Method for Unstructured Meshes. [Masters Thesis]. University of Toronto; 2011. Available from: http://hdl.handle.net/1807/29528

Texas A&M University

17. Freno, Brian Andrew. Reduced-order Models for Computational Aeroelasticity.

Degree: PhD, Aerospace Engineering, 2013, Texas A&M University

URL: http://hdl.handle.net/1969.1/151757

► This dissertation presents a proper orthogonal decomposition (POD) method that uses dynamic basis functions. The dynamic functions are of a prescribed form and do not… (more)

Subjects/Keywords: Proper orthogonal decomposition; Reduced-order modeling; Deforming mesh; Dynamic basis functions; Computational fluid dynamics; Grassmann manifold

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APA (6^th Edition):

Freno, B. A. (2013). Reduced-order Models for Computational Aeroelasticity. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/151757

Chicago Manual of Style (16^th Edition):

Freno, Brian Andrew. “Reduced-order Models for Computational Aeroelasticity.” 2013. Doctoral Dissertation, Texas A&M University. Accessed April 16, 2021. http://hdl.handle.net/1969.1/151757.

MLA Handbook (7^th Edition):

Freno, Brian Andrew. “Reduced-order Models for Computational Aeroelasticity.” 2013. Web. 16 Apr 2021.

Vancouver:

Freno BA. Reduced-order Models for Computational Aeroelasticity. [Internet] [Doctoral dissertation]. Texas A&M University; 2013. [cited 2021 Apr 16]. Available from: http://hdl.handle.net/1969.1/151757.

Council of Science Editors:

Freno BA. Reduced-order Models for Computational Aeroelasticity. [Doctoral Dissertation]. Texas A&M University; 2013. Available from: http://hdl.handle.net/1969.1/151757

University of Colorado

18. Mitchell, Wayne Bradford. Low-Communication, Parallel Multigrid Algorithms for Elliptic Partial Differential Equations.

Degree: PhD, 2017, University of Colorado

URL: https://scholar.colorado.edu/appm_gradetds/126

► When solving elliptic partial differential equations (PDE's) multigrid algorithms often provide optimal solvers and preconditioners capable of providing solutions with O(N) computational cost, where… (more)

▼ When solving elliptic partial differential equations (PDE's) multigrid algorithms often provide optimal solvers and preconditioners capable of providing solutions with O(N) computational cost, where N is the number of unknowns. As parallelism of modern super computers continues to grow towards exascale, however, the cost of communication has overshadowed the cost of computation as the next major bottleneck for multigrid algorithms. Typically, multigrid algorithms require O((log P)²) communication steps in order to solve a PDE problem to the level of discretization accuracy, where P is the number of processors. This has inspired the development of new algorithms that employ novel paradigms for parallelizing PDE problems, and this thesis studies and further develops two such algorithms. The nested iteration with range decomposition (NIRD) algorithm is known to achieve accuracy similar to that of traditional methods in only a single iteration with log P communication steps for simple elliptic problems. This thesis makes several improvements to the NIRD algorithm and extends its application to a much wider variety of problems, while also examining and updating previously proposed convergence theory and performance models. The second method studied is the algebraic multigrid with domain decomposition (AMG-DD) algorithm. Though previous work showed only marginal benefits when comparing convergence factors for AMG-DD against standard AMG V-cycles, this thesis studies the potential of AMG-DD as a discretization-accuracy solver. In addition to detailing the first parallel implementation of this algorithm, this thesis also shows new results that study the effect of different AMG coarsening and interpolation strategies on AMG-DD convergence and show some evidence to suggest AMG-DD may achieve discretization accuracy in a fixed number of cycles with O(log P) communication cost even as problem size increases. Advisors/Committee Members: Thomas A. Manteuffel, Stephen F. McCormick, John Ruge.

Subjects/Keywords: adaptive mesh refinement; algebraic multigrid; domain decomposition; first-order system least-squares; nested iteration; range decomposition; Applied Mathematics; Partial Differential Equations

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

APA (6^th Edition):

Mitchell, W. B. (2017). Low-Communication, Parallel Multigrid Algorithms for Elliptic Partial Differential Equations. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/appm_gradetds/126

Chicago Manual of Style (16^th Edition):

Mitchell, Wayne Bradford. “Low-Communication, Parallel Multigrid Algorithms for Elliptic Partial Differential Equations.” 2017. Doctoral Dissertation, University of Colorado. Accessed April 16, 2021. https://scholar.colorado.edu/appm_gradetds/126.

MLA Handbook (7^th Edition):

Mitchell, Wayne Bradford. “Low-Communication, Parallel Multigrid Algorithms for Elliptic Partial Differential Equations.” 2017. Web. 16 Apr 2021.

Vancouver:

Mitchell WB. Low-Communication, Parallel Multigrid Algorithms for Elliptic Partial Differential Equations. [Internet] [Doctoral dissertation]. University of Colorado; 2017. [cited 2021 Apr 16]. Available from: https://scholar.colorado.edu/appm_gradetds/126.

Council of Science Editors:

Mitchell WB. Low-Communication, Parallel Multigrid Algorithms for Elliptic Partial Differential Equations. [Doctoral Dissertation]. University of Colorado; 2017. Available from: https://scholar.colorado.edu/appm_gradetds/126

Iowa State University

19. Zhou, Ying. Development of the spectral difference method and application in the numerical investigation of the separated and transitional flows over a low-Reynolds number airfoil.

Degree: 2011, Iowa State University

URL: https://lib.dr.iastate.edu/etd/10207

► The development of the high-order accuracy spectral difference (SD) method on hexahedral mesh and its applications in aeroacoustic and aerodynamic problems are carried out in… (more)

▼ The development of the high-order accuracy spectral difference (SD) method on hexahedral mesh and its applications in aeroacoustic and aerodynamic problems are carried out in this work. Two absorbing boundary conditions, the absorbing sponge zone and the perfectly matched layer, are developed and implemented for the SD method discretizing the Euler and Navier-Stokes equations on unstructured grids. The performance of both boundary conditions is evaluated and compared with the characteristic boundary condition for a variety of benchmark problems including vortex and acoustic wave propagations. The applications of the perfectly matched layer technique in the numerical simulations of unsteady problems with complex geometries are also presented to demonstrate its capability. Numerical simulations of the low-Reynolds number (Re= 〖10〗⁴ ~ 〖10〗⁵ ) flows over a SD7003 airfoil at moderate incidences (<10y) are performed. A low-frequency convective instability is observed to dominate the spectrum near the leading edge and be responsible for the growth of the disturbance in the attached boundary layer. The characteristic frequency, the growth rate and the wave shape are investigated based on the numerical results. The growth of the low-frequency instability is not in agreement with parallel flow stability theory, nor with leading edge receptivity theory. And it has a higher growth rate than the Tollmien-Schlichting (T-S) wave. The effects of the angle-of-attack (AoA), the Reynolds number and the airfoil geometry on the low-frequency instability are investigated and discussed. The mechanisms in the breakdown process are investigated and discussed. it is observed that the breakdown of the shedding vortices starts at approximately the location with the maximum negative streamwise flow velocity. And the reverse flow in the separation region directly triggers the generation of three dimensional disturbances and the streamwise vorticities. In addition, the secondary instability which initiates the breakdown process differs in cases at different AOAs. The elliptic and hyperbolic instabilities observed in bluff-body wakes are found to occur in the breakdown process of current cases. Furthermore, the sequence of breakdown states at various incidences is found to be similar to that of the bluff-body wakes at various Reynolds numbers. A numerical investigation of passive LSB control techniques using roughness bumps on a low-Reynolds number wing is conducted as a further study. The previous case at Re=6y〖10〗⁴ and AoA=4y is used as the baseline (uncontrolled) case. In the controlled cases, roughness bumps are strategically placed near the leading edge of the wing for the purpose of improving aerodynamic performance in terms of the lift to drag ratio. The location, bump size, the number of bumps and the AoA are varied to study the effects. The pressure drag forces in the controlled cases are found to be reduced significantly when the LSB are reduced or avoided, resulting in much improved lift over drag ratio.

Subjects/Keywords: absorbing boundary condition; computational fluid dynamics; high-order method; passive flow control; separation and transition; unstructured mesh; Aerospace Engineering

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APA (6^th Edition):

Zhou, Y. (2011). Development of the spectral difference method and application in the numerical investigation of the separated and transitional flows over a low-Reynolds number airfoil. (Thesis). Iowa State University. Retrieved from https://lib.dr.iastate.edu/etd/10207

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Zhou, Ying. “Development of the spectral difference method and application in the numerical investigation of the separated and transitional flows over a low-Reynolds number airfoil.” 2011. Thesis, Iowa State University. Accessed April 16, 2021. https://lib.dr.iastate.edu/etd/10207.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Zhou, Ying. “Development of the spectral difference method and application in the numerical investigation of the separated and transitional flows over a low-Reynolds number airfoil.” 2011. Web. 16 Apr 2021.

Vancouver:

Zhou Y. Development of the spectral difference method and application in the numerical investigation of the separated and transitional flows over a low-Reynolds number airfoil. [Internet] [Thesis]. Iowa State University; 2011. [cited 2021 Apr 16]. Available from: https://lib.dr.iastate.edu/etd/10207.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Zhou Y. Development of the spectral difference method and application in the numerical investigation of the separated and transitional flows over a low-Reynolds number airfoil. [Thesis]. Iowa State University; 2011. Available from: https://lib.dr.iastate.edu/etd/10207

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Delft University of Technology

20. Ravichandran, T.K. (author). Investigation of Accuracy, Speed and Stability of Hyper-Reduction Techniques for Nonlinear FE.

Degree: 2016, Delft University of Technology

URL: http://resolver.tudelft.nl/uuid:310c611c-2225-4fa1-8a92-bd48d82a6722

►

The field of Hyper-reduction for Nonlinear Finite Element Method attempts to address the large durations due to repeated evaluation and assembly of the internal force… (more)

Subjects/Keywords: Nonlinear Model order reduction; hyper-reduction; Galerkin projection; ECSW; DEIM; structure preserving DEIM; nonlinear finite element; refine mesh

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

APA (6^th Edition):

Ravichandran, T. K. (. (2016). Investigation of Accuracy, Speed and Stability of Hyper-Reduction Techniques for Nonlinear FE. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:310c611c-2225-4fa1-8a92-bd48d82a6722

Chicago Manual of Style (16^th Edition):

Ravichandran, T K (author). “Investigation of Accuracy, Speed and Stability of Hyper-Reduction Techniques for Nonlinear FE.” 2016. Masters Thesis, Delft University of Technology. Accessed April 16, 2021. http://resolver.tudelft.nl/uuid:310c611c-2225-4fa1-8a92-bd48d82a6722.

MLA Handbook (7^th Edition):

Ravichandran, T K (author). “Investigation of Accuracy, Speed and Stability of Hyper-Reduction Techniques for Nonlinear FE.” 2016. Web. 16 Apr 2021.

Vancouver:

Ravichandran TK(. Investigation of Accuracy, Speed and Stability of Hyper-Reduction Techniques for Nonlinear FE. [Internet] [Masters thesis]. Delft University of Technology; 2016. [cited 2021 Apr 16]. Available from: http://resolver.tudelft.nl/uuid:310c611c-2225-4fa1-8a92-bd48d82a6722.

Council of Science Editors:

Ravichandran TK(. Investigation of Accuracy, Speed and Stability of Hyper-Reduction Techniques for Nonlinear FE. [Masters Thesis]. Delft University of Technology; 2016. Available from: http://resolver.tudelft.nl/uuid:310c611c-2225-4fa1-8a92-bd48d82a6722

King Abdullah University of Science and Technology

21. Al-Marouf, Mohamad. A Versatile Embedded Boundary Adaptive Mesh Method for Compressible Flow in Complex Geometry.

Degree: Physical Science and Engineering (PSE) Division, 2018, King Abdullah University of Science and Technology

URL: http://hdl.handle.net/10754/630093

► We present an Embedded Boundary with Adaptive Mesh Refinement technique for solving the compressible Navier Stokes equations in arbitrary complex domains; followed by a numerical… (more)

▼ We present an Embedded Boundary with Adaptive Mesh Refinement technique for solving the compressible Navier Stokes equations in arbitrary complex domains; followed by a numerical studies for the effect of circular cylinders on the transient dynamics of the Richtmyer-Meshkov Instability. A PDE multidimensional extrapolation approach is used to reconstruct the solution in the ghost-fluid regions and imposing boundary conditions on the fluid-solid interface, coupled with a multi-dimensional algebraic interpolation for freshly cleared cells. The Navier Stokes equations are numerically solved by the second order multidimensional upwind method. Block-structured AMR, implemented with the Chombo framework, is utilized to reduce the computational cost while keeping high resolution mesh around the Embedded Boundary and regions of high gradient solutions. The versatility of the method is demonstrated via several numerical examples, in both static and moving geometry, ranging from low Mach number nearly incompressible to supersonic flows. Our simulation results are extensively verified against other numerical results and validated against available experimental results where applicable. The effects on the transient dynamics of the Richtmyer-Meshkov instability due to small scale perturbations introduced on the shock-wave or the material interface by a single or set of solid circular cylinders were computationally investigated using the developed technique. First, we discuss the RMI initiated on a flat interface by a rippled shock-wave that is disturbed by a single circular cylinder. Then, we study the effect of introducing a number of circular cylinders on the interface. The arrangement of the cylinders set mimic (in a two dimensional domain) the presence of the solid supporting grid wires used in the formation of the material interface in the experimental setup. We analyzed their effects on the mixing layer growth and the mixedness level, and qualitatively demonstrate the cylinders' perturbation effects on the mixing layer structure. We modeled the cylinders' influence based on their diameters; and showed the model ability to predict the variation of the mixing layer growth for different flow parameters. Advisors/Committee Members: Samtaney, Ravi (advisor), Thoroddsen, Sigurdur T (committee member), Keyes, David E. (committee member), Colella, Phillip (committee member).

Subjects/Keywords: Computational fluid dynamics; Compressible flow; High-order reconstruction algorithm; Cartesian approach; Adaptive mesh refinement; Richtmyer-Meshkov instability

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

APA (6^th Edition):

Al-Marouf, M. (2018). A Versatile Embedded Boundary Adaptive Mesh Method for Compressible Flow in Complex Geometry. (Thesis). King Abdullah University of Science and Technology. Retrieved from http://hdl.handle.net/10754/630093

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Al-Marouf, Mohamad. “A Versatile Embedded Boundary Adaptive Mesh Method for Compressible Flow in Complex Geometry.” 2018. Thesis, King Abdullah University of Science and Technology. Accessed April 16, 2021. http://hdl.handle.net/10754/630093.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Al-Marouf, Mohamad. “A Versatile Embedded Boundary Adaptive Mesh Method for Compressible Flow in Complex Geometry.” 2018. Web. 16 Apr 2021.

Vancouver:

Al-Marouf M. A Versatile Embedded Boundary Adaptive Mesh Method for Compressible Flow in Complex Geometry. [Internet] [Thesis]. King Abdullah University of Science and Technology; 2018. [cited 2021 Apr 16]. Available from: http://hdl.handle.net/10754/630093.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Al-Marouf M. A Versatile Embedded Boundary Adaptive Mesh Method for Compressible Flow in Complex Geometry. [Thesis]. King Abdullah University of Science and Technology; 2018. Available from: http://hdl.handle.net/10754/630093

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

22. Jeferson Brambatti Granjeiro. Um método robusto de volumes finitos de alta ordem para advecção em malhas esféricas geodésicas.

Degree: 2019, University of São Paulo

URL: http://www.teses.usp.br/teses/disponiveis/45/45132/tde-26082019-163438/

►

A esfera é comumente usada como domínio computacional para representar o planeta Terra. Dessa forma, é possível modelar diversos fenômenos físicos, como a previsão numérica… (more)

▼

A esfera é comumente usada como domínio computacional para representar o planeta Terra. Dessa forma, é possível modelar diversos fenômenos físicos, como a previsão numérica do tempo. A discretização pode ser feita de formas distintas, mas devido a uma crescente necessidade de eficiência computacional, as malhas geodésicas têm ganhado a atenção da comunidade científica. Dentre as quais, por serem mais isotrópicas em relação às malhas latitude/longitude, destacam-se as malhas icosaédricas. A qualidade dos modelos de previsão do tempo é fortemente influenciada pela precisão da solução da equação de advecção (ou transporte), pois, é necessário avaliar o transporte de diversas substâncias presentes na atmosfera. Nesse contexto, pesquisadores têm se interessado em desenvolver métodos de alta ordem na esfera para melhorar a qualidade da solução do transporte escalar. Apesar de existirem alguns modelos numéricos de alta ordem que usam malhas icosaédricas, não há consenso sobre as metodologias e os tipos de malhas a serem utilizadas. O objetivo deste trabalho foi estudar os métodos disponíveis na literatura e propor um novo método de alta ordem na esfera, baseado nos trabalhos de Ollivier-Gooch e colaboradores. O método de volumes finitos de alta ordem foi validado com testes de interpolação, integração e discretização do divergente. Por fim, foram utilizadas várias funções testes para a advecção. Os resultados foram comparados com os da literatura para malhas icosaédricas com distintas otimizações. Os testes incluem funções suaves, com descontinuidades e testes de deformações na distribuição do campo transportado, que são fundamentais no desenvolvimento de modelos atmosféricos globais. Os resultados numéricos mostram que o método proposto, que será denominado por FV-OLG, foi capaz de obter alta ordem de precisão e verificou-se que as taxas de erro são pouco influenciadas por distorções de malha. Foi feito um teste adicional para avaliar o transporte de uma colina de gaussiana na malha icosaédrica com refinamento local. Os resultados obtidos demonstram que as taxas de convergências são as mesmas obtidas em malhas com distintas otimizações, demonstrando ser um método robusto a ser explorado em modelos atmosféricos globais.

The sphere is commonly used as a computational domain to represent the planet Earth. In this way, it is possible to model several physical phenomena, such as the numerical weather forecast. Discretization can be done in different ways, but due to an increasing need for computational efficiency, geodesic meshes have gained the attention of the scientific community. These are more isotropic in relation to the latitude / longitude meshes, among which, the icosahedral meshes stand out. The quality of weather forecast models is strongly influenced by the accuracy of the solution of the advection (or transport) equation, since it is necessary to evaluate the transport of various substances present in the atmosphere. In this context, researchers have been interested in developing high-order methods on…

Advisors/Committee Members: Pedro da Silva Peixoto, Saulo Rabello Maciel de Barros, Pedro Leite da Silva Dias, Wellington Carlos de Jesus, Ernani Vitillo Volpe.

Subjects/Keywords: Advecção; Alta ordem; Malha icosaédrica; Malhas geodésicas; Transporte; Volumes finitos; Advection; Finite volumes; Geodesic grids; High order; Icosahedral mesh; Transport

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

APA (6^th Edition):

Granjeiro, J. B. (2019). Um método robusto de volumes finitos de alta ordem para advecção em malhas esféricas geodésicas. (Doctoral Dissertation). University of São Paulo. Retrieved from http://www.teses.usp.br/teses/disponiveis/45/45132/tde-26082019-163438/

Chicago Manual of Style (16^th Edition):

Granjeiro, Jeferson Brambatti. “Um método robusto de volumes finitos de alta ordem para advecção em malhas esféricas geodésicas.” 2019. Doctoral Dissertation, University of São Paulo. Accessed April 16, 2021. http://www.teses.usp.br/teses/disponiveis/45/45132/tde-26082019-163438/.

MLA Handbook (7^th Edition):

Granjeiro, Jeferson Brambatti. “Um método robusto de volumes finitos de alta ordem para advecção em malhas esféricas geodésicas.” 2019. Web. 16 Apr 2021.

Vancouver:

Granjeiro JB. Um método robusto de volumes finitos de alta ordem para advecção em malhas esféricas geodésicas. [Internet] [Doctoral dissertation]. University of São Paulo; 2019. [cited 2021 Apr 16]. Available from: http://www.teses.usp.br/teses/disponiveis/45/45132/tde-26082019-163438/.

Council of Science Editors:

Granjeiro JB. Um método robusto de volumes finitos de alta ordem para advecção em malhas esféricas geodésicas. [Doctoral Dissertation]. University of São Paulo; 2019. Available from: http://www.teses.usp.br/teses/disponiveis/45/45132/tde-26082019-163438/

University of Florida

23. Colvin, Cheryl Halpern. Are sibling roles altered when one child has diabetes?.

Degree: 1996, University of Florida

URL: https://ufdc.ufl.edu/AA00026549

Subjects/Keywords: Child psychology; Children; Chronic conditions; Diabetes; Disabilities; Health status; Mothers; Parents; Siblings; Type 1 diabetes mellitus; Birth Order ( mesh ); Department of Clinical and Health Psychology thesis Ph.D ( mesh ); Diabetes Mellitus ( mesh ); Health Status ( mesh ); Sibling Relations ( mesh )

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

APA (6^th Edition):

Colvin, C. H. (1996). Are sibling roles altered when one child has diabetes?. (Thesis). University of Florida. Retrieved from https://ufdc.ufl.edu/AA00026549

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Colvin, Cheryl Halpern. “Are sibling roles altered when one child has diabetes?.” 1996. Thesis, University of Florida. Accessed April 16, 2021. https://ufdc.ufl.edu/AA00026549.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Colvin, Cheryl Halpern. “Are sibling roles altered when one child has diabetes?.” 1996. Web. 16 Apr 2021.

Vancouver:

Colvin CH. Are sibling roles altered when one child has diabetes?. [Internet] [Thesis]. University of Florida; 1996. [cited 2021 Apr 16]. Available from: https://ufdc.ufl.edu/AA00026549.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Colvin CH. Are sibling roles altered when one child has diabetes?. [Thesis]. University of Florida; 1996. Available from: https://ufdc.ufl.edu/AA00026549

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Mississippi State University

24. Wu, Huangli. computational simulation of dynamics of nematic liquid crystals in the presence of nanoparticles and biological macromolecules.

Degree: MS, Computational Engineering, 2006, Mississippi State University

URL: http://sun.library.msstate.edu/ETD-db/theses/available/etd-06152006-204622/ ;

► Recent research shows that liquid crystals can be used to report the presence of different types of substances through optical amplication of ligand-receptor binding. In… (more)

Subjects/Keywords: liquid crystal; disclination line; saturn ring; tensor order paramenter; unstructured mesh

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APA (6^th Edition):

Wu, H. (2006). computational simulation of dynamics of nematic liquid crystals in the presence of nanoparticles and biological macromolecules. (Masters Thesis). Mississippi State University. Retrieved from http://sun.library.msstate.edu/ETD-db/theses/available/etd-06152006-204622/ ;

Chicago Manual of Style (16^th Edition):

Wu, Huangli. “computational simulation of dynamics of nematic liquid crystals in the presence of nanoparticles and biological macromolecules.” 2006. Masters Thesis, Mississippi State University. Accessed April 16, 2021. http://sun.library.msstate.edu/ETD-db/theses/available/etd-06152006-204622/ ;.

MLA Handbook (7^th Edition):

Wu, Huangli. “computational simulation of dynamics of nematic liquid crystals in the presence of nanoparticles and biological macromolecules.” 2006. Web. 16 Apr 2021.

Vancouver:

Wu H. computational simulation of dynamics of nematic liquid crystals in the presence of nanoparticles and biological macromolecules. [Internet] [Masters thesis]. Mississippi State University; 2006. [cited 2021 Apr 16]. Available from: http://sun.library.msstate.edu/ETD-db/theses/available/etd-06152006-204622/ ;.

Council of Science Editors:

Wu H. computational simulation of dynamics of nematic liquid crystals in the presence of nanoparticles and biological macromolecules. [Masters Thesis]. Mississippi State University; 2006. Available from: http://sun.library.msstate.edu/ETD-db/theses/available/etd-06152006-204622/ ;

University of Colorado

25. Mitchell, Wayne. Low-Communication, Parallel Multigrid Algorithms for Elliptic Partial Differential Equations.

Degree: PhD, Applied Mathematics, 2017, University of Colorado

URL: https://scholar.colorado.edu/appm_gradetds/80

► When solving elliptic partial differential equations (PDE's) multigrid algorithms often provide optimal solvers and preconditioners capable of providing solutions with O(N) computational cost, where… (more)

▼ When solving elliptic partial differential equations (PDE's) multigrid algorithms often provide optimal solvers and preconditioners capable of providing solutions with O(N) computational cost, where N is the number of unknowns. As parallelism of modern super computers continues to grow towards exascale, however, the cost of communication has overshadowed the cost of computation as the next major bottleneck for multigrid algorithms. Typically, multigrid algorithms require O((log P)²) communication steps in order to solve a PDE problem to the level of discretization accuracy, where P is the number of processors. This has inspired the development of new algorithms that employ novel paradigms for parallelizing PDE problems, and this thesis studies and further develops two such algorithms. The nested iteration with range decomposition (NIRD) algorithm is known to achieve accuracy similar to that of traditional methods in only a single iteration with log P communication steps for simple elliptic problems. This thesis makes several improvements to the NIRD algorithm and extends its application to a much wider variety of problems, while also examining and updating previously proposed convergence theory and performance models. The second method studied is the algebraic multigrid with domain decomposition (AMG-DD) algorithm. Though previous work showed only marginal benefits when comparing convergence factors for AMG-DD against standard AMG V-cycles, this thesis studies the potential of AMG-DD as a discretization-accuracy solver. In addition to detailing the first parallel implementation of this algorithm, this thesis also shows new results that study the effect of different AMG coarsening and interpolation strategies on AMG-DD convergence and show some evidence to suggest AMG-DD may achieve discretization accuracy in a fixed number of cycles with O(log P) communication cost even as problem size increases. Advisors/Committee Members: Thomas A. Manteuffel, Stephen F. McCormick.

Subjects/Keywords: nested iteration; first-order system least-squares; algebraic multigrid; domain decomposition; range decomposition; adaptive mesh refinement; Applied Mathematics; Numerical Analysis and Computation; Partial Differential Equations

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

APA (6^th Edition):

Mitchell, W. (2017). Low-Communication, Parallel Multigrid Algorithms for Elliptic Partial Differential Equations. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/appm_gradetds/80

Chicago Manual of Style (16^th Edition):

Mitchell, Wayne. “Low-Communication, Parallel Multigrid Algorithms for Elliptic Partial Differential Equations.” 2017. Doctoral Dissertation, University of Colorado. Accessed April 16, 2021. https://scholar.colorado.edu/appm_gradetds/80.

MLA Handbook (7^th Edition):

Mitchell, Wayne. “Low-Communication, Parallel Multigrid Algorithms for Elliptic Partial Differential Equations.” 2017. Web. 16 Apr 2021.

Vancouver:

Mitchell W. Low-Communication, Parallel Multigrid Algorithms for Elliptic Partial Differential Equations. [Internet] [Doctoral dissertation]. University of Colorado; 2017. [cited 2021 Apr 16]. Available from: https://scholar.colorado.edu/appm_gradetds/80.

Council of Science Editors:

Mitchell W. Low-Communication, Parallel Multigrid Algorithms for Elliptic Partial Differential Equations. [Doctoral Dissertation]. University of Colorado; 2017. Available from: https://scholar.colorado.edu/appm_gradetds/80

26. POH LEONG HIEN. Gradient Enhanced Plasticity and Damage Models ¿ addressing the limitations of classical models in softening and hardening.

Degree: 2011, National University of Singapore

URL: http://scholarbank.nus.edu.sg/handle/10635/28521

Subjects/Keywords: Higher-order continua; Gradient formulation; Homogenization theory; Size effect; Mesh dependency; Finite elements

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

APA (6^th Edition):

HIEN, P. L. (2011). Gradient Enhanced Plasticity and Damage Models ¿ addressing the limitations of classical models in softening and hardening. (Thesis). National University of Singapore. Retrieved from http://scholarbank.nus.edu.sg/handle/10635/28521

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

HIEN, POH LEONG. “Gradient Enhanced Plasticity and Damage Models ¿ addressing the limitations of classical models in softening and hardening.” 2011. Thesis, National University of Singapore. Accessed April 16, 2021. http://scholarbank.nus.edu.sg/handle/10635/28521.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

HIEN, POH LEONG. “Gradient Enhanced Plasticity and Damage Models ¿ addressing the limitations of classical models in softening and hardening.” 2011. Web. 16 Apr 2021.

Vancouver:

HIEN PL. Gradient Enhanced Plasticity and Damage Models ¿ addressing the limitations of classical models in softening and hardening. [Internet] [Thesis]. National University of Singapore; 2011. [cited 2021 Apr 16]. Available from: http://scholarbank.nus.edu.sg/handle/10635/28521.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

HIEN PL. Gradient Enhanced Plasticity and Damage Models ¿ addressing the limitations of classical models in softening and hardening. [Thesis]. National University of Singapore; 2011. Available from: http://scholarbank.nus.edu.sg/handle/10635/28521

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

27. Mittal, Ketan. Highly scalable solution of incompressible Navier-Stokes equations using the spectral element method with overlapping grids.

Degree: PhD, Mechanical Engineering, 2019, University of Illinois – Urbana-Champaign

URL: http://hdl.handle.net/2142/106322

► We present a highly-flexible Schwarz overlapping framework for simulating turbulent fluid/thermal transport in complex domains. The approach is based on a variant of the Schwarz… (more)

Subjects/Keywords: Overlapping grids; Mesh optimization; High-order; Fluid-dynamics

…x5B;68, 69, 70]. Recently, high-order mesh optimization methods have been presented in… …mind key aspects of automated mesh generation methods. High-order meshes are typically… …order to maximize the quality of the given mesh. 15 Existing mesh smoothing methods, to the… …Scaling for Mesh Optimization . . . . . . . . 8.6 Summary… …9.9 Mesh Smoothing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.9.1 Flow past…

10 more images…

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

APA (6^th Edition):

Mittal, K. (2019). Highly scalable solution of incompressible Navier-Stokes equations using the spectral element method with overlapping grids. (Doctoral Dissertation). University of Illinois – Urbana-Champaign. Retrieved from http://hdl.handle.net/2142/106322

Chicago Manual of Style (16^th Edition):

Mittal, Ketan. “Highly scalable solution of incompressible Navier-Stokes equations using the spectral element method with overlapping grids.” 2019. Doctoral Dissertation, University of Illinois – Urbana-Champaign. Accessed April 16, 2021. http://hdl.handle.net/2142/106322.

MLA Handbook (7^th Edition):

Mittal, Ketan. “Highly scalable solution of incompressible Navier-Stokes equations using the spectral element method with overlapping grids.” 2019. Web. 16 Apr 2021.

Vancouver:

Mittal K. Highly scalable solution of incompressible Navier-Stokes equations using the spectral element method with overlapping grids. [Internet] [Doctoral dissertation]. University of Illinois – Urbana-Champaign; 2019. [cited 2021 Apr 16]. Available from: http://hdl.handle.net/2142/106322.

Council of Science Editors:

Mittal K. Highly scalable solution of incompressible Navier-Stokes equations using the spectral element method with overlapping grids. [Doctoral Dissertation]. University of Illinois – Urbana-Champaign; 2019. Available from: http://hdl.handle.net/2142/106322

28. Kontzialis, Konstantinos. High-order discontinuous Galerkin discretization for flows with strong moving shocks.

Degree: 2012, University of Patras; Πανεπιστήμιο Πατρών

URL: http://hdl.handle.net/10442/hedi/28649

► Supersonic flows over both simple and complex geometries involve features over a wide spectrum of spatial and temporal scales, whose resolution in a numerical solution… (more)

▼ Supersonic flows over both simple and complex geometries involve features over a wide spectrum of spatial and temporal scales, whose resolution in a numerical solution is of significant importance for accurate predictions in engineering applications. While CFD has been greatly developed in the last 30 years, the desire and necessity to perform more complex, high fidelity simulations still remains. The present thesis has introduced two major innovations regarding the fidelity of numerical solutions of the compressible \ns equations. The first one is the development of new a priori mesh quality measures for the Finite Volume (FV) method on mixed-type (quadrilateral/triangular) element meshes. Elementary types of mesh distortion were identified expressing grid distortion in terms of stretching, skewness, shearing and non-alignment of the mesh. Through a rigorous truncation error analysis, novel grid quality measures were derived by emphasizing on the direct relation between mesh distortion and the quality indicators. They were applied over several meshes and their ability was observed to identify faithfully irregularly-shaped small or large distortions in any direction. It was concluded that accuracy degradation occurs even for small mesh distortions and especially at mixed-type element mesh interfaces the formal order of the FV method is degraded no matter of the mesh geometry and local mesh size. Therefore, in the present work, the high-order Discontinuous Galerkin (DG) discretization of the compressible flow equations was adopted as a means of achieving and attaining high resolution of flow features on irregular mixed-type meshes for flows with strong moving shocks. During the course of the thesis a code was developed and named HoAc (standing for High Order Accuracy), which can perform via the domain decomposition method parallel p-adaptive computations for flows with strong shocks on mixed-type element meshes over arbitrary geometries at a predefined arbitrary order of accuracy. In HoAc in contrast to other DG developments, all the numerical operations are performed in the computational space, for all element types. This choice constitutes the key element for the ability to perform p-adaptive computations along with modal hierarchical basis for the solution expansion. The time marching of the DG discretized Navier-Stokes system is performed with the aid of explicit Runge-Kutta methods or with a matrix-free implicit approach. The second innovation of the present thesis, which is also based on the choice of implementing the DG method on the regular computational space, is the development of a new p-adaptive limiting procedure for shock capturing of the implemented DG discretization. The new limiting approach along with positivity preserving limiters is suitable for computations of high speed flows with strong shocks around complex geometries. The unified approach for p-adaptive limiting on mixed-type meshes is achieved by applying the limiters on the transformed canonical elements, and it is fully automated…

Subjects/Keywords: Ασυνεχή πεπερασμένα στοιχεία; Υψηλής τάξης; Ανάδειξη κρουστικών κυμάτων; Δείκτες ποιότητας πλέγματος; P-προσαρμοστικότητα; Περιοριστές; Discontinous galerkin; High order; Shock capturing; Mesh quality measures; P-adaptive; Limiters

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

APA (6^th Edition):

Kontzialis, K. (2012). High-order discontinuous Galerkin discretization for flows with strong moving shocks. (Thesis). University of Patras; Πανεπιστήμιο Πατρών. Retrieved from http://hdl.handle.net/10442/hedi/28649

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Kontzialis, Konstantinos. “High-order discontinuous Galerkin discretization for flows with strong moving shocks.” 2012. Thesis, University of Patras; Πανεπιστήμιο Πατρών. Accessed April 16, 2021. http://hdl.handle.net/10442/hedi/28649.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Kontzialis, Konstantinos. “High-order discontinuous Galerkin discretization for flows with strong moving shocks.” 2012. Web. 16 Apr 2021.

Vancouver:

Kontzialis K. High-order discontinuous Galerkin discretization for flows with strong moving shocks. [Internet] [Thesis]. University of Patras; Πανεπιστήμιο Πατρών; 2012. [cited 2021 Apr 16]. Available from: http://hdl.handle.net/10442/hedi/28649.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Kontzialis K. High-order discontinuous Galerkin discretization for flows with strong moving shocks. [Thesis]. University of Patras; Πανεπιστήμιο Πατρών; 2012. Available from: http://hdl.handle.net/10442/hedi/28649

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

29. Sy, Birame. Adaptabilité en espace d'un schéma volumes finis d'ordre élevé pour la CFD/CAA des turbomachines : Spatial adaptibility of a high order finite volumes scheme for CFD/CAA in turbomachinery.

Degree: Docteur es, Génie énergétique (AM), 2020, Paris, HESAM

URL: http://www.theses.fr/2020HESAE045

►

A l’ère du numérique, le cycle de développement d’un produit se fait dans sa quasi totalité sur ordinateur. Il n’est plus nécessaire de produire physiquement… (more)

▼

A l’ère du numérique, le cycle de développement d’un produit se fait dans sa quasi totalité sur ordinateur. Il n’est plus nécessaire de produire physiquement des versions préliminaires. Leurs caractéristiques peuvent être testées avec une précision dépendante de la maturité des méthodes de simulation. Les acteurs de la recherche en simulation numérique ont donc pour défi de transposer leurs récentes avancées vers l’industrie. En mécanique des fluides, les codes de calcul doivent gagner en adaptabilité afin de prendre en compte la morphologie du problème et du maillage. Le paramétrage des méthodes avancées doit pouvoir être délégué par l’utilisateur non-expert à la machine. Ce travail de recherche porte sur l’adaptabilité en espace d’un schéma volumes finis d’ordre élevé (FV-MLS). L’ordre élevé est un élément indispensable afin de capter les phénomènes fortement instationnaires.Pour augmenter l’ordre de précision, le schéma FV-MLS fait intervenir une reconstruction polynomiale d’ordre élevé par Moindres Carrés Mobiles. MLS affiche un fort potentiel en terme de flexibilité pour traiter des géométries complexes. Elle possède par ailleurs un nombre important de paramètres pouvant être intégrés dans un procédé d’optimisation. Ces travaux ont tout d’abord apporté des réponses concernant la sensibilité de la méthode vis-à-vis des paramètres MLS. À un second niveau, une série d’algorithmes de choix pertinent de ces paramètres a été mise au point, tout en améliorant nettement la robustesse, la précision et l’efficacité de calcul. La charge de l’utilisateur a ainsi été réduite de manière conséquente, lui permettant de se recentrer sur son cœur de métier. Cette méthodologie a été validée jusqu’à l’ordre 6. Pour améliorer la robustesse au schéma numérique vis-à-vis de l’anisotropie du maillage, un nouveau cadre de reconstruction locale d’ordre élevée a été défini.Cette reconstruction locale permet de réduire drastiquement les effets de l’anisotropie. Plusieurs cas de validation et exemples d’applications ont été réalisé afin de démonter l’intérêt des méthodes proposées.

In the digital age, almost all of a product’s development cycle is done on a computer. There is no longer a need to physically produce drafts. Their characteristics can be tested with precision that depends on the maturity of the simulation methods. Researchers in digital simulation therefore have the challenge of transferring their recent advances to industry. In fluid mechanics, the computer codes must gain in adaptability in order to take into account the morphology of the problem and the mesh.The configuration of advanced methods should be delegated by the non-expert user to the machine.This research work focused on the adaptability in space of a high order finite volume scheme (FV-MLS). The high order is an essential element in order to capture highly unsteady phenomena. To increase the order of precision, the FV-MLS scheme involves a high order polynomial reconstruction by Least Mobile Squares. MLS has great potential in terms of flexibility for handling…

Advisors/Committee Members: Khelladi, Sofiane (thesis director), Deligant, Michaël (thesis director).

Subjects/Keywords: Ordres élevés; Volumes finis; Adaptabilité; Turbomachine; Aérodynamique; Aéroacoustique; Maillage glissant; CFD; CAA; High order; Finite volume; Turbomachinery; Aerodynamics; Aeroacoustic; MLS; Moving least Square; Stencil; Adaptive; Sliding-mesh; 621.042

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

APA (6^th Edition):

Sy, B. (2020). Adaptabilité en espace d'un schéma volumes finis d'ordre élevé pour la CFD/CAA des turbomachines : Spatial adaptibility of a high order finite volumes scheme for CFD/CAA in turbomachinery. (Doctoral Dissertation). Paris, HESAM. Retrieved from http://www.theses.fr/2020HESAE045

Chicago Manual of Style (16^th Edition):

Sy, Birame. “Adaptabilité en espace d'un schéma volumes finis d'ordre élevé pour la CFD/CAA des turbomachines : Spatial adaptibility of a high order finite volumes scheme for CFD/CAA in turbomachinery.” 2020. Doctoral Dissertation, Paris, HESAM. Accessed April 16, 2021. http://www.theses.fr/2020HESAE045.

MLA Handbook (7^th Edition):

Sy, Birame. “Adaptabilité en espace d'un schéma volumes finis d'ordre élevé pour la CFD/CAA des turbomachines : Spatial adaptibility of a high order finite volumes scheme for CFD/CAA in turbomachinery.” 2020. Web. 16 Apr 2021.

Vancouver:

Sy B. Adaptabilité en espace d'un schéma volumes finis d'ordre élevé pour la CFD/CAA des turbomachines : Spatial adaptibility of a high order finite volumes scheme for CFD/CAA in turbomachinery. [Internet] [Doctoral dissertation]. Paris, HESAM; 2020. [cited 2021 Apr 16]. Available from: http://www.theses.fr/2020HESAE045.

Council of Science Editors:

Sy B. Adaptabilité en espace d'un schéma volumes finis d'ordre élevé pour la CFD/CAA des turbomachines : Spatial adaptibility of a high order finite volumes scheme for CFD/CAA in turbomachinery. [Doctoral Dissertation]. Paris, HESAM; 2020. Available from: http://www.theses.fr/2020HESAE045

30. Gobé, Alexis. Méthodes Galerkin discontinues pour la simulation de problèmes multiéchelles en nanophotonique et applications au piégeage de la lumière dans des cellules solaires : Discontinuous Galerkin methods for the simulation of multiscale nanophotonic problems with application to light trapping in solar cells.

Degree: Docteur es, Mathématiques, 2020, Université Côte d'Azur

URL: http://www.theses.fr/2020COAZ4011

►

L’objectif de cette thèse est l’étude numérique du piégeage de la lumière dans des cellules solaires nanostructurées. Le changement climatique est devenu une problématique majeure… (more)

▼

L’objectif de cette thèse est l’étude numérique du piégeage de la lumière dans des cellules solaires nanostructurées. Le changement climatique est devenu une problématique majeure nécessitant une transition énergétique à court terme. Dans ce contexte, l'énergie solaire semble être une source énergétique idéale. Cette ressource est à la fois scalable à l’échelle planétaire et écologique. Afin de maximiser sa pénétration, des travaux visant à augmenter la quantité de lumière absorbée et à réduire les coûts liés à la conception des cellules sont nécessaires. Le piégeage de la lumière est une stratégie qui permet d’atteindre ces deux objectifs. Son principe consiste à utiliser des texturations nanométriques afin de focaliser la lumière dans les couches de semi-conducteur absorbantes. Dans ce travail, la méthode de Galerkine Discontinue en Domaine Temporel (DGTD) est introduite. Deux développements méthodologiques majeurs, permettant de mieux prendre en compte les caractéristiques des cellules solaires, sont présentés. Tout d'abord, l’utilisation d’un ordre d’approximation local est proposé , basé sur une stratégie de répartition particulière de l’ordre. Le deuxième développement est l’utilisation de maillage hybride mixant ses élements hexahédriques structurés et tétrahédriques non structurés. Des cas réalistes de cellules solaires issus de la littérature et de collaborations avec des physiciens du domaine du photovoltaïque permettent d'illustrer l' apport de ces développements. Un cas d’optimisation inverse de réseau de diffraction dans une cellule solaire est également présenté en couplant le solveur numérique avec un algorithme d’optimisation bayésienne. De plus, une étude approfondie des performances du solveur a également été réalisée avec des modifications méthodologiques pour contrer les problèmes de répartition de charge. Enfin, une méthode plus prospective, la méthode Multiéchelle Hybride-Mixte (MHM) spécialisée dans la résolution de problème très fortement multiéchelle est introduite. Un schéma en temps multiéchelle est présenté et sa stabilité prouvée.

The objective of this thesis is the numerical study of light trapping in nanostructured solar cells. Climate change has become a major issue requiring a short-term energy transition. In this context, solar energy seems to be an ideal energy source. This resource is both globally scalable and environmentally friendly. In order to maximize its penetration, it is needed to increase the amount of light absorbed and reduce the costs associated with cell design. Light trapping is a strategy that achieves both of these objectives. The principle is to use nanometric textures to focus the light in the absorbing semiconductor layers. In this work, the Discontinuous Galerkin Time-Domain (DGTD) method is introduced. Two major methodological developments are presented, allowing to better take into account the characteristics of solar cells. First, the use of a local approximation order is proposed, based on a particular order distribution strategy. The second development…

Advisors/Committee Members: Lanteri, Stéphane (thesis director).

Subjects/Keywords: Équations de Maxwell; Méthode de Galerkine discontinue; Matériaux dispersifs; Photovoltaique; Piégeage de la lumière; Nanophotonique; Maillage hybride; Maillage non conforme; Méthode d’ordre élevé; Méthode multi échelle; Optimisation; Calcul haute performance; Maxwell’s equations; Discontinuous Galerkin method; Dispersive materials; Photovoltaics; Light trapping; Nanophotonics; Hybrid mesh; Non conform mesh; High order method; Multiscale method; Optimization; High performance computing

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

APA (6^th Edition):

Gobé, A. (2020). Méthodes Galerkin discontinues pour la simulation de problèmes multiéchelles en nanophotonique et applications au piégeage de la lumière dans des cellules solaires : Discontinuous Galerkin methods for the simulation of multiscale nanophotonic problems with application to light trapping in solar cells. (Doctoral Dissertation). Université Côte d'Azur. Retrieved from http://www.theses.fr/2020COAZ4011

Chicago Manual of Style (16^th Edition):

Gobé, Alexis. “Méthodes Galerkin discontinues pour la simulation de problèmes multiéchelles en nanophotonique et applications au piégeage de la lumière dans des cellules solaires : Discontinuous Galerkin methods for the simulation of multiscale nanophotonic problems with application to light trapping in solar cells.” 2020. Doctoral Dissertation, Université Côte d'Azur. Accessed April 16, 2021. http://www.theses.fr/2020COAZ4011.

MLA Handbook (7^th Edition):

Gobé, Alexis. “Méthodes Galerkin discontinues pour la simulation de problèmes multiéchelles en nanophotonique et applications au piégeage de la lumière dans des cellules solaires : Discontinuous Galerkin methods for the simulation of multiscale nanophotonic problems with application to light trapping in solar cells.” 2020. Web. 16 Apr 2021.

Vancouver:

Gobé A. Méthodes Galerkin discontinues pour la simulation de problèmes multiéchelles en nanophotonique et applications au piégeage de la lumière dans des cellules solaires : Discontinuous Galerkin methods for the simulation of multiscale nanophotonic problems with application to light trapping in solar cells. [Internet] [Doctoral dissertation]. Université Côte d'Azur; 2020. [cited 2021 Apr 16]. Available from: http://www.theses.fr/2020COAZ4011.

Council of Science Editors:

Gobé A. Méthodes Galerkin discontinues pour la simulation de problèmes multiéchelles en nanophotonique et applications au piégeage de la lumière dans des cellules solaires : Discontinuous Galerkin methods for the simulation of multiscale nanophotonic problems with application to light trapping in solar cells. [Doctoral Dissertation]. Université Côte d'Azur; 2020. Available from: http://www.theses.fr/2020COAZ4011

Open Access Theses and Dissertations