subject:(domain decomposition)

1. Steiner, Johannes. Coupling different discretizations for fluid structure interaction in a monolithic approach.

Degree: 2014, Università della Svizzera italiana

► In this thesis we present a monolithic coupling approach for the simulation of phenomena involving interacting fluid and structure using different discretizations for the subproblems.… (more)

▼ In this thesis we present a monolithic coupling approach for the simulation of phenomena involving interacting fluid and structure using different discretizations for the subproblems. For many applications in fluid dynamics, the Finite Volume method is the first choice in simulation science. Likewise, for the simulation of structural mechanics the Finite Element method is one of the most, if not the most, popular discretization method. However, despite the advantages of these discretizations in their respective application domains, monolithic coupling schemes have so far been restricted to a single discretization for both subproblems. We present a fluid structure coupling scheme based on a mixed Finite Volume/Finite Element method that combines the benefits of these discretizations. An important challenge in coupling fluid and structure is the transfer of forces and velocities at the fluidstructure interface in a stable and efficient way. In our approach this is achieved by means of a fully implicit formulation, i.e., the transfer of forces and displacements is carried out in a common set of equations for fluid and structure. We assemble the two different discretizations for the fluid and structure subproblems as well as the coupling conditions for forces and displacements into a single large algebraic system. Since we simulate real world problems, as a consequence of the complexity of the considered geometries, we end up with algebraic systems with a large number of degrees of freedom. This necessitates the use of parallel solution techniques. Our work covers the design and implementation of the proposed heterogeneous monolithic coupling approach as well as the efficient solution of the arising large nonlinear systems on distributed memory supercomputers. We apply Newton’s method to linearize the fully implicit coupled nonlinear fluid structure interaction problem. The resulting linear system is solved with a Krylov subspace correction method. For the preconditioning of the iterative solver we propose the use of multilevel methods. Specifically, we study a multigrid as well as a two-level restricted additive Schwarz method. We illustrate the performance of our method on a benchmark example and compare the afore mentioned different preconditioning strategies for the parallel solution of the monolithic coupled system. Advisors/Committee Members: Rolf (Dir.).

Subjects/Keywords: Domain decomposition

10 more images…

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Steiner, J. (2014). Coupling different discretizations for fluid structure interaction in a monolithic approach. (Thesis). Università della Svizzera italiana. Retrieved from http://doc.rero.ch/record/234355

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):

Steiner, Johannes. “Coupling different discretizations for fluid structure interaction in a monolithic approach.” 2014. Thesis, Università della Svizzera italiana. Accessed February 27, 2021. http://doc.rero.ch/record/234355.

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

MLA Handbook (7^th Edition):

Steiner, Johannes. “Coupling different discretizations for fluid structure interaction in a monolithic approach.” 2014. Web. 27 Feb 2021.

Vancouver:

Steiner J. Coupling different discretizations for fluid structure interaction in a monolithic approach. [Internet] [Thesis]. Università della Svizzera italiana; 2014. [cited 2021 Feb 27]. Available from: http://doc.rero.ch/record/234355.

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

Council of Science Editors:

Steiner J. Coupling different discretizations for fluid structure interaction in a monolithic approach. [Thesis]. Università della Svizzera italiana; 2014. Available from: http://doc.rero.ch/record/234355

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

Université de Neuchâtel

2. Doucouré, Souleymane. Méthodes de décomposition de domaines pour les équations de Navier-Stokes en jonction fleuve/océan et les lois de conservation scalaires.

Degree: 2012, Université de Neuchâtel

URL: http://doc.rero.ch/record/29139

► L’objet de cette thèse est l’approximation du point de vue mathématique et numérique des équations de Navier-Stokes anisotropiques et des lois de conservations scalaires… (more)

Subjects/Keywords: Domain decomposition method

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Doucouré, S. (2012). Méthodes de décomposition de domaines pour les équations de Navier-Stokes en jonction fleuve/océan et les lois de conservation scalaires. (Thesis). Université de Neuchâtel. Retrieved from http://doc.rero.ch/record/29139

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):

Doucouré, Souleymane. “Méthodes de décomposition de domaines pour les équations de Navier-Stokes en jonction fleuve/océan et les lois de conservation scalaires.” 2012. Thesis, Université de Neuchâtel. Accessed February 27, 2021. http://doc.rero.ch/record/29139.

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

MLA Handbook (7^th Edition):

Doucouré, Souleymane. “Méthodes de décomposition de domaines pour les équations de Navier-Stokes en jonction fleuve/océan et les lois de conservation scalaires.” 2012. Web. 27 Feb 2021.

Vancouver:

Doucouré S. Méthodes de décomposition de domaines pour les équations de Navier-Stokes en jonction fleuve/océan et les lois de conservation scalaires. [Internet] [Thesis]. Université de Neuchâtel; 2012. [cited 2021 Feb 27]. Available from: http://doc.rero.ch/record/29139.

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

Council of Science Editors:

Doucouré S. Méthodes de décomposition de domaines pour les équations de Navier-Stokes en jonction fleuve/océan et les lois de conservation scalaires. [Thesis]. Université de Neuchâtel; 2012. Available from: http://doc.rero.ch/record/29139

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

University of Houston

3. Kurzanova, Daria 1989-. Efficient Numerical Treatment of High-contrast Diffusion Problems.

Degree: PhD, Mathematics, 2017, University of Houston

URL: http://hdl.handle.net/10657/4541

► This dissertation concerns efficient numerical treatment of the elliptic partial differential equations with high-contrast coefficients. High-contrast means that the ratio between highest and lowest values… (more)

Subjects/Keywords: High-contrast; Preconditioning; Lancsoz method; Domain decomposition

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Kurzanova, D. 1. (2017). Efficient Numerical Treatment of High-contrast Diffusion Problems. (Doctoral Dissertation). University of Houston. Retrieved from http://hdl.handle.net/10657/4541

Chicago Manual of Style (16^th Edition):

Kurzanova, Daria 1989-. “Efficient Numerical Treatment of High-contrast Diffusion Problems.” 2017. Doctoral Dissertation, University of Houston. Accessed February 27, 2021. http://hdl.handle.net/10657/4541.

MLA Handbook (7^th Edition):

Kurzanova, Daria 1989-. “Efficient Numerical Treatment of High-contrast Diffusion Problems.” 2017. Web. 27 Feb 2021.

Vancouver:

Kurzanova D1. Efficient Numerical Treatment of High-contrast Diffusion Problems. [Internet] [Doctoral dissertation]. University of Houston; 2017. [cited 2021 Feb 27]. Available from: http://hdl.handle.net/10657/4541.

Council of Science Editors:

Kurzanova D1. Efficient Numerical Treatment of High-contrast Diffusion Problems. [Doctoral Dissertation]. University of Houston; 2017. Available from: http://hdl.handle.net/10657/4541

4. Galia, Antonio. A Dynamic Homogenization Method for Nuclear Reactor Core Calculations : Une méthode d'homogénéisation dynamique pour les calculs de réacteurs nucléaires.

Degree: Docteur es, Énergie nucléaire, 2020, université Paris-Saclay

URL: http://www.theses.fr/2020UPASP042

►

Dans les calculs de réacteurs à trois dimensions, nombreuses techniques d'homogénéisation ont été développées pour l'utilisation du schéma de calcul classique à deux étapes, basé… (more)

▼

Dans les calculs de réacteurs à trois dimensions, nombreuses techniques d'homogénéisation ont été développées pour l'utilisation du schéma de calcul classique à deux étapes, basé sur les sections efficaces homogénéisées au préalable et utilisées ensuite par interpolation pour un état physique donné.D'autre part, les schémas de calcul basées principalement sur les méthodes des caractéristiques, qui visent le calcul direct du réacteur sans homogénéisation, ont des performances encore limitées en raison des capacités des machines et font alors le recours à des solutions de transport simplifiées. Ce travail a pour objectif d'étudier une nouvelle approche dans laquelle l'homogénéisation dynamique est utilisée pourproduire le flux neutronique de pondération sur les modèles d'assemblage tridimensionnels. L'application de la méthode pour un calcul d'un REP en 3D est comparée aux résultats issus d'un calcul de référence numérique en transport 3D et d'un calcul classique à deux-étapes. La réalisation repose sur le calcul de haute performance et avec un haut niveau de parallélisme.

Three-dimensional deterministic core calculations are typically based on the classical two-step approach, where the homogenized cross sections of an assembly type are pre-calculated and then interpolated to the actual state in the reactor. The weighting flux used for cross-section homogenization is determined assuming the fundamental mode condition and using a critical-leakage modelthat does not account for the actual environment of an assembly. On the other hand, 3D direct transport calculations and the 2D/1D Fusion method, mostly based on the method of characteristics, have recently been applied showing excellent agreement with reference Monte-Carlo code, but still remaining computationally expensive for multiphysics applications and core depletioncalculations.In the present work, we propose a method of Dynamic Homogenization as an alternative technique for 3D core calculations, in the framework of domain decomposition method that can be massively parallelized. It consists of an iterative process between core and assembly calculationsthat preserves assembly exchanges. The main features of this approach are:i) cross-sections homogenization takes into account the environment of each assembly in the core;ii) the reflector can be homogenized with its realistic 2D geometry and its environment;iii) the method avoids expensive 3D transport calculations;iv) no “off-line” calculation and therefore v) no cross-section interpolation is required.The verification tests on 2D and 3D full core problems are presented applying several homogenization and equivalence techniques, comparing against direct 3D transport calculation. For this analysis, we solved the NEA “PWR MOX/UO2 Core Benchmark” problem, which is characterized by strong radial heterogeneities due to the presence of different types of UOx and MOx assemblies at different burnups. The obtained results show the advantages of the proposed method in terms of precision with respect to two-step and…

Advisors/Committee Members: Sanchez, Richard (thesis director).

Subjects/Keywords: Calcul Coeur; Théorie d'Homogénéisation; Decomposition de domaine; HPC; Core Calculation; Homogenization Theory; Domain Decomposition; HPC

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Galia, A. (2020). A Dynamic Homogenization Method for Nuclear Reactor Core Calculations : Une méthode d'homogénéisation dynamique pour les calculs de réacteurs nucléaires. (Doctoral Dissertation). université Paris-Saclay. Retrieved from http://www.theses.fr/2020UPASP042

Chicago Manual of Style (16^th Edition):

Galia, Antonio. “A Dynamic Homogenization Method for Nuclear Reactor Core Calculations : Une méthode d'homogénéisation dynamique pour les calculs de réacteurs nucléaires.” 2020. Doctoral Dissertation, université Paris-Saclay. Accessed February 27, 2021. http://www.theses.fr/2020UPASP042.

MLA Handbook (7^th Edition):

Galia, Antonio. “A Dynamic Homogenization Method for Nuclear Reactor Core Calculations : Une méthode d'homogénéisation dynamique pour les calculs de réacteurs nucléaires.” 2020. Web. 27 Feb 2021.

Vancouver:

Galia A. A Dynamic Homogenization Method for Nuclear Reactor Core Calculations : Une méthode d'homogénéisation dynamique pour les calculs de réacteurs nucléaires. [Internet] [Doctoral dissertation]. université Paris-Saclay; 2020. [cited 2021 Feb 27]. Available from: http://www.theses.fr/2020UPASP042.

Council of Science Editors:

Galia A. A Dynamic Homogenization Method for Nuclear Reactor Core Calculations : Une méthode d'homogénéisation dynamique pour les calculs de réacteurs nucléaires. [Doctoral Dissertation]. université Paris-Saclay; 2020. Available from: http://www.theses.fr/2020UPASP042

Duke University

5. Sun, Qingtao. Discontinuous Galerkin Based Multi-Domain Multi-Solver Technique for Efficient Multiscale Electromagnetic Modeling .

Degree: 2017, Duke University

URL: http://hdl.handle.net/10161/14378

► Discontinuous Galerkin (DG) methods provide an efficient option for modeling multiscale problems. With the help of the Riemann solver (upwind flux), a discontinuous Galerkin… (more)

▼ Discontinuous Galerkin (DG) methods provide an efficient option for modeling multiscale problems. With the help of the Riemann solver (upwind flux), a discontinuous Galerkin based multi-domain multi-solver technique is introduced in this work for multiscale electromagnetic modeling. Specifically, the proposed technique allows multiple subdomains and multiple solvers. Through multiple subdomains, the original large linear system is reduced into multiple subsystems to solve, thus reducing computational complexity. Different subdomains can be non-conformal with each other. Different element types (tetrahedron, hexahedron, Yee's cell) and element sizes (h-refinement) can be used with different orders of basis functions (p-refinement). For different solvers, the finite element method, spectral element method and finite difference method are incorporated into the proposed technique. As is well known, the finite element method features great mesh flexibility for arbitrarily shaped objects, the spectral element method shows spectral accuracy with high order basis functions, and the finite difference method has great computational efficiency for time domain modeling. With multiple solvers the proposed technique can provide efficient solution for multiscale problems based on different element types. Considering the model geometry, for irregular and complicated structures the finite element method is used with small tetrahedron elements for local refinement, for simple structures the spectral method is used with high order basis functions based on hexahedron elements to exploit its spectral accuracy, and for perfectly matched layer (PML) and layered structures the finite different method is used to improve computational efficiency. For time domain modeling, firstly hybrid spectral element-finite element method in time domain (hybrid SETD-FETD) is implemented based on the first-order Maxwell's curl equations. To facilitate modeling of electrically small problems, an efficient implicit non-iterative time integration method is proposed based the EB scheme for sequentially ordered systems. Compared with the previous Block-Thomas algorithm, the proposed block Lower-Diagonal-Upper (LDU) decomposition algorithm shows better performance in terms of CPU time and memory, due to the separation of surface unknowns from the volume unknowns. Then a second-order wave equation based discontinuous Galerkin time domain (DGTD) framework is proposed with a modified Riemann solver to evaluate the flux. Compared with the first-order Maxwell's curl equations based DGTD methods, the new DGTD framework reduces the degrees of freedom for each subdomain by solving the E unknowns plus only surface H unknowns. By contrast, the first-order Maxwell's curl equations based DGTD methods require to solve all the E and B unknowns in each subdomain. To model open problems, a novel coupling method is proposed to incorporate PML into the wave equation based DGTD framework. The PML region is based on the first-order Maxwell's curl equations based DGTD… Advisors/Committee Members: Liu, Qing Huo (advisor).

Subjects/Keywords: Electrical engineering; discontinuous Galerkin; domain decomposition; electromagnetic modeling; multi-domain; multiscale; multi-solver

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Sun, Q. (2017). Discontinuous Galerkin Based Multi-Domain Multi-Solver Technique for Efficient Multiscale Electromagnetic Modeling . (Thesis). Duke University. Retrieved from http://hdl.handle.net/10161/14378

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):

Sun, Qingtao. “Discontinuous Galerkin Based Multi-Domain Multi-Solver Technique for Efficient Multiscale Electromagnetic Modeling .” 2017. Thesis, Duke University. Accessed February 27, 2021. http://hdl.handle.net/10161/14378.

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

MLA Handbook (7^th Edition):

Sun, Qingtao. “Discontinuous Galerkin Based Multi-Domain Multi-Solver Technique for Efficient Multiscale Electromagnetic Modeling .” 2017. Web. 27 Feb 2021.

Vancouver:

Sun Q. Discontinuous Galerkin Based Multi-Domain Multi-Solver Technique for Efficient Multiscale Electromagnetic Modeling . [Internet] [Thesis]. Duke University; 2017. [cited 2021 Feb 27]. Available from: http://hdl.handle.net/10161/14378.

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

Council of Science Editors:

Sun Q. Discontinuous Galerkin Based Multi-Domain Multi-Solver Technique for Efficient Multiscale Electromagnetic Modeling . [Thesis]. Duke University; 2017. Available from: http://hdl.handle.net/10161/14378

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

Temple University

6. Garay, Jose. Asynchronous Optimized Schwarz Methods for Partial Differential Equations in Rectangular Domains.

Degree: PhD, 2018, Temple University

URL: http://digital.library.temple.edu/u?/p245801coll10,510451

►

Mathematics

Asynchronous iterative algorithms are parallel iterative algorithms in which communications and iterations are not synchronized among processors. Thus, as soon as a processing unit… (more)

▼

Mathematics

Asynchronous iterative algorithms are parallel iterative algorithms in which communications and iterations are not synchronized among processors. Thus, as soon as a processing unit finishes its own calculations, it starts the next cycle with the latest data received during a previous cycle, without waiting for any other processing unit to complete its own calculation. These algorithms increase the number of updates in some processors (as compared to the synchronous case) but suppress most idle times. This usually results in a reduction of the (execution) time to achieve convergence. Optimized Schwarz methods (OSM) are domain decomposition methods in which the transmission conditions between subdomains contain operators of the form \linebreak \partial/\partial ν +Λ, where \partial/\partial ν is the outward normal derivative and Λ is an optimized local approximation of the global Steklov-Poincar\'e operator. There is more than one family of transmission conditions that can be used for a given partial differential equation (e.g., the OO0 and OO2 families), each of these families containing a particular approximation of the Steklov-Poincar\'e operator. These transmission conditions have some parameters that are tuned to obtain a fast convergence rate. Optimized Schwarz methods are fast in terms of iteration count and can be implemented asynchronously. In this thesis we analyze the convergence behavior of the synchronous and asynchronous implementation of OSM applied to solve partial differential equations with a shifted Laplacian operator in bounded rectangular domains. We analyze two cases. In the first case we have a shift that can be either positive, negative or zero, a one-way domain decomposition and transmission conditions of the OO2 family. In the second case we have Poisson's equation, a domain decomposition with cross-points and OO0 transmission conditions. In both cases we reformulate the equations defining the problem into a fixed point iteration that is suitable for our analysis, then derive convergence proofs and analyze how the convergence rate varies with the number of subdomains, the amount of overlap, and the values of the parameters introduced in the transmission conditions. Additionally, we find the optimal values of the parameters and present some numerical experiments for the second case illustrating our theoretical results. To our knowledge this is the first time that a convergence analysis of optimized Schwarz is presented for bounded subdomains with multiple subdomains and arbitrary overlap. The analysis presented in this thesis also applies to problems with more general domains which can be decomposed as a union of rectangles.

Temple University – Theses

Advisors/Committee Members: Szyld, Daniel;, Szyld, Daniel, Magoulès, F. (Frédéric), Queisser, Gillian, Seibold, Benjamin;.

Subjects/Keywords: Applied mathematics; Mathematics;

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Garay, J. (2018). Asynchronous Optimized Schwarz Methods for Partial Differential Equations in Rectangular Domains. (Doctoral Dissertation). Temple University. Retrieved from http://digital.library.temple.edu/u?/p245801coll10,510451

Chicago Manual of Style (16^th Edition):

Garay, Jose. “Asynchronous Optimized Schwarz Methods for Partial Differential Equations in Rectangular Domains.” 2018. Doctoral Dissertation, Temple University. Accessed February 27, 2021. http://digital.library.temple.edu/u?/p245801coll10,510451.

MLA Handbook (7^th Edition):

Garay, Jose. “Asynchronous Optimized Schwarz Methods for Partial Differential Equations in Rectangular Domains.” 2018. Web. 27 Feb 2021.

Vancouver:

Garay J. Asynchronous Optimized Schwarz Methods for Partial Differential Equations in Rectangular Domains. [Internet] [Doctoral dissertation]. Temple University; 2018. [cited 2021 Feb 27]. Available from: http://digital.library.temple.edu/u?/p245801coll10,510451.

Council of Science Editors:

Garay J. Asynchronous Optimized Schwarz Methods for Partial Differential Equations in Rectangular Domains. [Doctoral Dissertation]. Temple University; 2018. Available from: http://digital.library.temple.edu/u?/p245801coll10,510451

NSYSU

7. Li, Yi-mou. Implementation of an Accelerated Domain Decomposition Iterative Procedure.

Degree: Master, Applied Mathematics, 2002, NSYSU

URL: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0715102-143756

► This paper is concerned about an implementation of an accelerated domain decomposition iterative procedure. In [4], Douglas and Huang had shown the convergence for one… (more)

Subjects/Keywords: domain decomposition; iterative procedure; implementation

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Li, Y. (2002). Implementation of an Accelerated Domain Decomposition Iterative Procedure. (Thesis). NSYSU. Retrieved from http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0715102-143756

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):

Li, Yi-mou. “Implementation of an Accelerated Domain Decomposition Iterative Procedure.” 2002. Thesis, NSYSU. Accessed February 27, 2021. http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0715102-143756.

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

MLA Handbook (7^th Edition):

Li, Yi-mou. “Implementation of an Accelerated Domain Decomposition Iterative Procedure.” 2002. Web. 27 Feb 2021.

Vancouver:

Li Y. Implementation of an Accelerated Domain Decomposition Iterative Procedure. [Internet] [Thesis]. NSYSU; 2002. [cited 2021 Feb 27]. Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0715102-143756.

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

Council of Science Editors:

Li Y. Implementation of an Accelerated Domain Decomposition Iterative Procedure. [Thesis]. NSYSU; 2002. Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0715102-143756

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

Universidade do Rio Grande do Sul

8. Almeida, Alexandre Vinicius. Uso de auto-tuning para otimização de decomposição de domínios paralela.

Degree: 2011, Universidade do Rio Grande do Sul

URL: http://hdl.handle.net/10183/39121

►

O desenvolvimento de aplicações de forma a atingir níveis de desempenho próximos aos níveis teóricos de uma determinada plataforma é uma tarefa que exige conhecimento… (more)

▼

O desenvolvimento de aplicações de forma a atingir níveis de desempenho próximos aos níveis teóricos de uma determinada plataforma é uma tarefa que exige conhecimento técnico do ambiente de hardware, uma vez que o software deve explorar detalhes específicos da plataforma em questão. Pelo fato do software ser específico à plataforma, caso ela evolua ou se altere, as otimizações realizadas podem não explorar a nova arquitetura de forma eficiente. Auto-tuners são sistemas que surgiram como um meio automatizado de adaptar um determinado software a uma arquitetura alvo. Essa adaptação ocorre através de uma busca empírica de valores ótimos para parâmetros específicos de uma aplicação, a fim de ajustá-los às características do hardware, ou ainda através da geração de códigofonte otimizado para a plataforma. Este trabalho propõe um módulo auto-tuner orientado à adaptação parametrizada de uma aplicação paralela, que trabalha variando os fatores da dimensão do domínio bidimensional, o número de processos e a extensão das regiões de sobreposição. Para cada variação dos fatores, o auto-tuner testa a aplicação na arquitetura paralela de forma a buscar a combinação de parâmetros com melhor desempenho. Para possibilitar o auto-tuning, foi desenvolvida uma classe em linguagem C++ denominada Mesh, baseada no padrão MPI. A classe busca abstrair a decomposição de domínios de uma aplicação paralela por meio do uso de Orientação a Objetos, e facilita a variação da extensão das regiões de sobreposição entre os subdomínios. Os resultados experimentais demonstraram que o auto-tuner explora o ganho de desempenho pela variação do número de processos da aplicação, que também é tratado pelo módulo auto-tuner. A arquitetura paralela utilizada na validação não se mostrou ideal para uma otimização através do aumento da extensão das regiões sobrepostas entre subdomínios.

Achieving the peak performance level of a particular platform requires technical knowledge of the hardware environment involved, since the software must explore specific details inherent to the hardware. Once the software is optimized for a target platform, if the hardware evolves or is changed, the software probably would not be as efficient in the new environment. This performance portability problem is addressed by software auto-tuning, which emerged in the past decade as an automated technique to adapt a particular software to an underlying hardware. The software adaptation is performed by an auto-tuner. The auto-tuner is an entity that empirically adjusts specific application parameters in order to improve the overall application performance, or even generates source-code optimized for the target platform. This dissertation proposes an auto-tuner to optimize the domain decomposition of a parallel application that performs stencil computations. The proposed auto-tuner works in a parameterized adaptation fashion, and varies the dimensions of a 2D domain, the number of parallel processes and the extension of the overlapping zones between subdomains. For each combination of…

Advisors/Committee Members: Maillard, Nicolas Bruno.

Subjects/Keywords: Mpi; Auto-tuning; Processamento paralelo; Domain decomposition; MPI; Paralelism

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Almeida, A. V. (2011). Uso de auto-tuning para otimização de decomposição de domínios paralela. (Thesis). Universidade do Rio Grande do Sul. Retrieved from http://hdl.handle.net/10183/39121

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):

Almeida, Alexandre Vinicius. “Uso de auto-tuning para otimização de decomposição de domínios paralela.” 2011. Thesis, Universidade do Rio Grande do Sul. Accessed February 27, 2021. http://hdl.handle.net/10183/39121.

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

MLA Handbook (7^th Edition):

Almeida, Alexandre Vinicius. “Uso de auto-tuning para otimização de decomposição de domínios paralela.” 2011. Web. 27 Feb 2021.

Vancouver:

Almeida AV. Uso de auto-tuning para otimização de decomposição de domínios paralela. [Internet] [Thesis]. Universidade do Rio Grande do Sul; 2011. [cited 2021 Feb 27]. Available from: http://hdl.handle.net/10183/39121.

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

Council of Science Editors:

Almeida AV. Uso de auto-tuning para otimização de decomposição de domínios paralela. [Thesis]. Universidade do Rio Grande do Sul; 2011. Available from: http://hdl.handle.net/10183/39121

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

Penn State University

9. Zerr, Robert Joseph. Solution of the Within-Group Multidimensional Discrete Ordinates Transport Equations on Massively Parallel Architectures.

Degree: 2011, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/11686

► The integral transport matrix method (ITMM) has been used as the kernel of new parallel solution methods for the discrete ordinates approximation of the within-group… (more)

▼ The integral transport matrix method (ITMM) has been used as the kernel of new parallel solution methods for the discrete ordinates approximation of the within-group neutron transport equation. The ITMM abandons the repetitive mesh sweeps of the traditional source iterations (SI) scheme in favor of constructing stored operators that account for the direct coupling factors among all the cells and between the cells and boundary surfaces. The main goals of this work were to develop the algorithms that construct these operators and employ them in the solution process, determine the most suitable way to parallelize the entire procedure, and evaluate the behavior and performance of the developed methods for increasing number of processes. This project compares the effectiveness of the ITMM with the SI scheme parallelized with the Koch-Baker-Alcouffe (KBA) method. The ITMM is applicable to any spatial discretization of the first-order form of the transport equation. For simplicity, a majority of the testing was performed using the well-known diamond difference spatial discretization. The ITMM has also been implemented with the AHOT-N discretization. Likewise, an isotropic treatment of the scattering term was used for primary testing of the new approach, and anisotropic scattering was implemented to demonstrate ITMM capabilities. The primary parallel solution method involves a decomposition of the domain into smaller spatial sub-domains, each with their own transport matrices, and coupled together via interface boundary angular fluxes. Each sub-domain has its own set of ITMM operators and represents an independent transport problem. Multiple iterative parallel solution methods have investigated, including parallel block Jacobi (PBJ), parallel red/black Gauss-Seidel (PGS), and parallel GMRES (PGMRES). The number of global iterations is a reflection of the coupling among the sub-domains. Tight coupling means that the transport effects of one sub-domain have significant impact on the flux of another sub-domain, and many iterations are needed for convergence. Loose coupling means effects are more localized. Increasing the scattering ratio c decreases neutron absorption, allowing them to travel farther through the domain and tightening the sub-domain coupling. Decreasing cell dimension h (or alternatively decreasing the total interaction cross section) decreases the optical thickness of the medium, meaning fewer neutron interactions and again longer distances between the neutron’s birth and death locations. The fastest observed parallel solution method, PGS, was used in a weak scaling comparison with the PARTISN code. Compared to the state-of-the-art SI-KBA with diffusion synthetic acceleration (DSA), this new method without acceleration/preconditioning is not competitive for any problem parameters considered. The best comparisons occur for problems that are difficult for SI DSA, namely highly scattering and optically thick. SI DSA execution time curves are generally steeper than the PGS ones. However, until further… Advisors/Committee Members: Dr Yousry Y Azmy, Dissertation Advisor/Co-Advisor, Yousry Y Azmy, Committee Chair/Co-Chair, Seungjin Kim, Committee Chair/Co-Chair, Kostadin Nikolov Ivanov, Committee Member, Lyle Norman Long, Committee Member, Randal S Baker, Committee Member.

Subjects/Keywords: neutron transport; discrete ordinates; within-group; massively parallel; spatial domain decomposition

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Zerr, R. J. (2011). Solution of the Within-Group Multidimensional Discrete Ordinates Transport Equations on Massively Parallel Architectures. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/11686

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):

Zerr, Robert Joseph. “Solution of the Within-Group Multidimensional Discrete Ordinates Transport Equations on Massively Parallel Architectures.” 2011. Thesis, Penn State University. Accessed February 27, 2021. https://submit-etda.libraries.psu.edu/catalog/11686.

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

MLA Handbook (7^th Edition):

Zerr, Robert Joseph. “Solution of the Within-Group Multidimensional Discrete Ordinates Transport Equations on Massively Parallel Architectures.” 2011. Web. 27 Feb 2021.

Vancouver:

Zerr RJ. Solution of the Within-Group Multidimensional Discrete Ordinates Transport Equations on Massively Parallel Architectures. [Internet] [Thesis]. Penn State University; 2011. [cited 2021 Feb 27]. Available from: https://submit-etda.libraries.psu.edu/catalog/11686.

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

Council of Science Editors:

Zerr RJ. Solution of the Within-Group Multidimensional Discrete Ordinates Transport Equations on Massively Parallel Architectures. [Thesis]. Penn State University; 2011. Available from: https://submit-etda.libraries.psu.edu/catalog/11686

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

Rice University

10. Kroeger, Nathaniel James. ADMM Based Methods for Time-Domain Decomposition Formulations of Optimal Control Problems.

Degree: MA, Engineering, 2020, Rice University

URL: http://hdl.handle.net/1911/109174

► This thesis investigates alternating direction method of multipliers (ADMM)-based methods for time-domain decomposition (TDD) formulations of linear-quadratic partial differential equation (PDE)-constrained optimization problems. The solution… (more)

Subjects/Keywords: Time Domain Decomposition; Alternating Direction Method of Multipliers; ADMM

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Kroeger, N. J. (2020). ADMM Based Methods for Time-Domain Decomposition Formulations of Optimal Control Problems. (Masters Thesis). Rice University. Retrieved from http://hdl.handle.net/1911/109174

Chicago Manual of Style (16^th Edition):

Kroeger, Nathaniel James. “ADMM Based Methods for Time-Domain Decomposition Formulations of Optimal Control Problems.” 2020. Masters Thesis, Rice University. Accessed February 27, 2021. http://hdl.handle.net/1911/109174.

MLA Handbook (7^th Edition):

Kroeger, Nathaniel James. “ADMM Based Methods for Time-Domain Decomposition Formulations of Optimal Control Problems.” 2020. Web. 27 Feb 2021.

Vancouver:

Kroeger NJ. ADMM Based Methods for Time-Domain Decomposition Formulations of Optimal Control Problems. [Internet] [Masters thesis]. Rice University; 2020. [cited 2021 Feb 27]. Available from: http://hdl.handle.net/1911/109174.

Council of Science Editors:

Kroeger NJ. ADMM Based Methods for Time-Domain Decomposition Formulations of Optimal Control Problems. [Masters Thesis]. Rice University; 2020. Available from: http://hdl.handle.net/1911/109174

11. Zhang, Yi. A numerical wave tank based on coupled potential flow-viscous flow model.

Degree: PhD, Civil Engineering, 2013, Oregon State University

URL: http://hdl.handle.net/1957/44850

► In this study, a coupled potential flow-viscous flow model is used for numerical wave tank simulation. The solver satisfies all the requirements for such a… (more)

Subjects/Keywords: domain decomposition; Viscous flow

…Domain decomposition method for heterogeneous flow model 2.3.1 Matching conditions… …2.3.2 A homogeneous domain decomposition method . . 2.3.3 The heterogeneous domain… …Domain decomposition method for the coupled flow model 3.3.1 Heterogeneous domain decomposition… …A nonoverlapping heterogeneous domain decomposition method for three– dimensional gravity… …91 scheme based on domain decomposition method Computational complexity…

10 more images…

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Zhang, Y. (2013). A numerical wave tank based on coupled potential flow-viscous flow model. (Doctoral Dissertation). Oregon State University. Retrieved from http://hdl.handle.net/1957/44850

Chicago Manual of Style (16^th Edition):

Zhang, Yi. “A numerical wave tank based on coupled potential flow-viscous flow model.” 2013. Doctoral Dissertation, Oregon State University. Accessed February 27, 2021. http://hdl.handle.net/1957/44850.

MLA Handbook (7^th Edition):

Zhang, Yi. “A numerical wave tank based on coupled potential flow-viscous flow model.” 2013. Web. 27 Feb 2021.

Vancouver:

Zhang Y. A numerical wave tank based on coupled potential flow-viscous flow model. [Internet] [Doctoral dissertation]. Oregon State University; 2013. [cited 2021 Feb 27]. Available from: http://hdl.handle.net/1957/44850.

Council of Science Editors:

Zhang Y. A numerical wave tank based on coupled potential flow-viscous flow model. [Doctoral Dissertation]. Oregon State University; 2013. Available from: http://hdl.handle.net/1957/44850

12. Desmeure, Geoffrey. Une stratégie de décomposition de domaine mixte et multiéchelle pour le calcul des assemblages. : A mixed multiscale domain decomposition method for structural assemblies design.

Degree: Docteur es, Mécanique des solides, 2016, Université Paris-Saclay (ComUE)

URL: http://www.theses.fr/2016SACLN011

►

Dans un contexte de grande concurrence internationale, la simulation numérique du comportement joue un rôle primordial dans le domaine aéronautique, permettant de réduire les délais… (more)

▼

Dans un contexte de grande concurrence internationale, la simulation numérique du comportement joue un rôle primordial dans le domaine aéronautique, permettant de réduire les délais et les coûts de conception, d'évaluer la pertinence de nouvelles solutions technologiques avant de se lancer dans les investissements qu'elles imposent. Visant la simulation de structures assemblées, ce travail de thèse a consisté a développer une méthode de décomposition de domaine mixte, multiéchelle, s’appuyant sur le solveur LaTIn. Afin de simplifier le traitement discret des quantités d'interface, la méthode proposée utilise un représentant des interefforts qui évolue dans le même espace que les déplacements d’interface (H¹/2). Elle s'appuie sur le produit scalaire associé à ces quantités pour le calcul des travaux d'interface. Délicat à calculer, ce produit scalaire est traité par une approximation validée numériquement. Le calcul de la matrice de masse pleine en découlant est récompensé par un taux de convergence montré indépendant du pas du maillage et de la taille des sous-domaines sur plusieurs cas-tests faisant intervenir notamment du contact.

Mechanical industries' need of liability in numerical simulations leads to evermore fine and complex models taking into account complicated physical behaviours. With the aim of modelling large complex structures, a non-overlapping mixed domain decomposition method based on a LaTIn-type iterative solver is proposed.The method relies on splitting the studied domain into substructures and interfaces which can both bear mechanical behaviors so that perfect cohesion, contact, delamination can be modelled by the interfaces. The associated solver enables to treat at small scales nonlinear phenomena and, as commonly done, scalabilty is ensured by a coarse problem. The method presented uses the Riesz representation theorem to represent interface tractions in H¹/2 in order to discretize them accordingly to the displacements. Independence of convergence and search direction's optimal value from mesh size is evidenced and high precision can be reached in few iterations.Different test-cases assess the method for perfect and contact interfaces.

Advisors/Committee Members: Rey, Christian (thesis director).

Subjects/Keywords: Décomposition de domaine; Multiechelle; LaTIn; Domain decomposition; Multiscale; LaTIn

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Desmeure, G. (2016). Une stratégie de décomposition de domaine mixte et multiéchelle pour le calcul des assemblages. : A mixed multiscale domain decomposition method for structural assemblies design. (Doctoral Dissertation). Université Paris-Saclay (ComUE). Retrieved from http://www.theses.fr/2016SACLN011

Chicago Manual of Style (16^th Edition):

Desmeure, Geoffrey. “Une stratégie de décomposition de domaine mixte et multiéchelle pour le calcul des assemblages. : A mixed multiscale domain decomposition method for structural assemblies design.” 2016. Doctoral Dissertation, Université Paris-Saclay (ComUE). Accessed February 27, 2021. http://www.theses.fr/2016SACLN011.

MLA Handbook (7^th Edition):

Desmeure, Geoffrey. “Une stratégie de décomposition de domaine mixte et multiéchelle pour le calcul des assemblages. : A mixed multiscale domain decomposition method for structural assemblies design.” 2016. Web. 27 Feb 2021.

Vancouver:

Desmeure G. Une stratégie de décomposition de domaine mixte et multiéchelle pour le calcul des assemblages. : A mixed multiscale domain decomposition method for structural assemblies design. [Internet] [Doctoral dissertation]. Université Paris-Saclay (ComUE); 2016. [cited 2021 Feb 27]. Available from: http://www.theses.fr/2016SACLN011.

Council of Science Editors:

Desmeure G. Une stratégie de décomposition de domaine mixte et multiéchelle pour le calcul des assemblages. : A mixed multiscale domain decomposition method for structural assemblies design. [Doctoral Dissertation]. Université Paris-Saclay (ComUE); 2016. Available from: http://www.theses.fr/2016SACLN011

Universidade Nova

13. Delgado, Nuno Miguel de Brito. A system’s approach to cache hierarchy-aware decomposition of data-parallel computations.

Degree: 2014, Universidade Nova

URL: http://www.rcaap.pt/detail.jsp?id=oai:run.unl.pt:10362/13014

►

Dissertação para obtenção do Grau de Mestre em Engenharia Informática

The architecture of nowadays’ processors is very complex, comprising several computational cores and an intricate… (more)

▼

Dissertação para obtenção do Grau de Mestre em Engenharia Informática

The architecture of nowadays’ processors is very complex, comprising several computational cores and an intricate hierarchy of cache memories. The latter, in particular, differ considerably between the many processors currently available in the market, resulting in a wide variety of configurations. Application development is typically oblivious of this complexity and diversity, taking only into consideration the number of available execution cores. This oblivion prevents such applications from fully harnessing the computing power available in these architectures. This problem has been recognized by the community, which has proposed languages and models to express and tune applications according to the underlying machine’s hierarchy. These, however, lack the desired abstraction level, forcing the programmer to have deep knowledge of computer architecture and parallel programming, in order to ensure performance portability across a wide range of architectures. Realizing these limitations, the goal of this thesis is to delegate these hierarchy-aware optimizations to the runtime system. Accordingly, the programmer’s responsibilities are confined to the definition of procedures for decomposing an application’s domain, into an arbitrary number of partitions. With this, the programmer has only to reason about the application’s data representation and manipulation. We prototyped our proposal on top of a Java parallel programming framework, and evaluated it from a performance perspective, against cache neglectful domain decompositions. The results demonstrate that our optimizations deliver significant speedups against decomposition strategies based solely on the number of execution cores, without requiring the programmer to reason about the machine’s hardware. These facts allow us to conclude that it is possible to obtain performance gains by transferring hierarchyaware optimizations concerns to the runtime system.

Advisors/Committee Members: Paulino, Hervé.

Subjects/Keywords: Data-parallelism; Hierarchical parallelism; Domain decomposition; Runtime systems

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Delgado, N. M. d. B. (2014). A system’s approach to cache hierarchy-aware decomposition of data-parallel computations. (Thesis). Universidade Nova. Retrieved from http://www.rcaap.pt/detail.jsp?id=oai:run.unl.pt:10362/13014

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):

Delgado, Nuno Miguel de Brito. “A system’s approach to cache hierarchy-aware decomposition of data-parallel computations.” 2014. Thesis, Universidade Nova. Accessed February 27, 2021. http://www.rcaap.pt/detail.jsp?id=oai:run.unl.pt:10362/13014.

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

MLA Handbook (7^th Edition):

Delgado, Nuno Miguel de Brito. “A system’s approach to cache hierarchy-aware decomposition of data-parallel computations.” 2014. Web. 27 Feb 2021.

Vancouver:

Delgado NMdB. A system’s approach to cache hierarchy-aware decomposition of data-parallel computations. [Internet] [Thesis]. Universidade Nova; 2014. [cited 2021 Feb 27]. Available from: http://www.rcaap.pt/detail.jsp?id=oai:run.unl.pt:10362/13014.

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

Council of Science Editors:

Delgado NMdB. A system’s approach to cache hierarchy-aware decomposition of data-parallel computations. [Thesis]. Universidade Nova; 2014. Available from: http://www.rcaap.pt/detail.jsp?id=oai:run.unl.pt:10362/13014

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

University of Manchester

14. Jones, Adam. Development of a near-wall domain decomposition method for turbulent flows.

Degree: Thesis (Eng.D.), 2016, University of Manchester

URL: https://www.research.manchester.ac.uk/portal/en/theses/development-of-a-nearwall-domain-decomposition-method-for-turbulent-flows(bf7149b7-c26a-4924-9886-42a92cce4f51).html ; http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.684768

► In computational fluid dynamics (CFD), there are two widely-used methods for computing the near-wall regions of turbulent flows: high Reynolds number (HRN) models and low… (more)

▼ In computational fluid dynamics (CFD), there are two widely-used methods for computing the near-wall regions of turbulent flows: high Reynolds number (HRN) models and low Reynolds number (LRN) models. HRN models do not resolve the near-wall region, but instead use wall functions to compute the required parameters over the near-wall region. In contrast, LRN models resolve the flow right down to the wall. Simulations with HRN models can take an order of magnitude less time than with LRN models, however the accuracy of the solution is reduced and certain requirements on the mesh must be met if the wall function is to be valid. It is often difficult or impossible to satisfy these requirements in industrial computations. In this thesis the near-wall domain decomposition (NDD) method of Utyuzhnikov (2006) is developed and implemented into the industrial code, Code_Saturne, for the first time. With the NDD approach, the near-wall regions of a fluid flow are removed from the main computational mesh. Instead, the mesh extends down to an interface boundary, which is located a short distance from the wall, denoted y*. A simplified boundary layer equation is used to calculate boundary conditions at the interface. When implemented with a turbulence model which can resolve down to the wall, there is no lower limit on the value of y*. There is a Reynolds number-dependent upper limit on y*, as there is with HRN models. Thus for large y*, the model functions as a HRN model and as y*→ 0 the LRN solution is recovered. NDD is implemented for the k−ε and Spalart-Allmaras turbulence models and is tested on five test cases: a channel flow at two different Reynolds numbers, an annular flow, an impinging jet flow and the flow in an asymmetric diffuser. The method is tested as a HRN and LRN model and it is found that the method behaves competitively with the scalable wall function (SWF) on simpler flows, and performs better on the asymmetric diffuser flow, where the NDD solution correctly captures the recirculation region whereas the SWF does not. The method is then tested on a ribbed channel flow. Particular focus is given to investigating how much of the rib can be excluded from the main computational mesh. It is found that it is possible to remove 90% of the rib from the mesh with less than 2% error in the friction factor compared to the LRN solution. The thesis then focuses on the industrial case of the flow in an annulus where the inner wall, referred to as the pin, has a rib on its surface that protrudes into the annulus. Comparison is made between CFD calculations, experimental data and empirical correlations. It is found that the experimental friction factors are significantly larger than those found with CFD, and that the trend in the friction factor with Reynolds number found in the experiments is different. Simulations are performed to quantify the effect that a non-smooth surface finish on the pin and rib surface has on the flow. This models the situation that occurs in an advanced gas-cooled nuclear reactor, when a carbon deposit…

Subjects/Keywords: 620.1; AGR; Domain decomposition; Code Saturne; Wall functions; RANS

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Jones, A. (2016). Development of a near-wall domain decomposition method for turbulent flows. (Doctoral Dissertation). University of Manchester. Retrieved from https://www.research.manchester.ac.uk/portal/en/theses/development-of-a-nearwall-domain-decomposition-method-for-turbulent-flows(bf7149b7-c26a-4924-9886-42a92cce4f51).html ; http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.684768

Chicago Manual of Style (16^th Edition):

Jones, Adam. “Development of a near-wall domain decomposition method for turbulent flows.” 2016. Doctoral Dissertation, University of Manchester. Accessed February 27, 2021. https://www.research.manchester.ac.uk/portal/en/theses/development-of-a-nearwall-domain-decomposition-method-for-turbulent-flows(bf7149b7-c26a-4924-9886-42a92cce4f51).html ; http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.684768.

MLA Handbook (7^th Edition):

Jones, Adam. “Development of a near-wall domain decomposition method for turbulent flows.” 2016. Web. 27 Feb 2021.

Vancouver:

Jones A. Development of a near-wall domain decomposition method for turbulent flows. [Internet] [Doctoral dissertation]. University of Manchester; 2016. [cited 2021 Feb 27]. Available from: https://www.research.manchester.ac.uk/portal/en/theses/development-of-a-nearwall-domain-decomposition-method-for-turbulent-flows(bf7149b7-c26a-4924-9886-42a92cce4f51).html ; http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.684768.

Council of Science Editors:

Jones A. Development of a near-wall domain decomposition method for turbulent flows. [Doctoral Dissertation]. University of Manchester; 2016. Available from: https://www.research.manchester.ac.uk/portal/en/theses/development-of-a-nearwall-domain-decomposition-method-for-turbulent-flows(bf7149b7-c26a-4924-9886-42a92cce4f51).html ; http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.684768

Delft University of Technology

15. Brakkee, E. Domain decomposition for the incompressible Navier-Stokes equations.

Degree: 1996, Delft University of Technology

URL: http://resolver.tudelft.nl/uuid:6840c5ea-824e-4d35-abc3-bcac2e228fab ; urn:NBN:nl:ui:24-uuid:6840c5ea-824e-4d35-abc3-bcac2e228fab ; urn:NBN:nl:ui:24-uuid:6840c5ea-824e-4d35-abc3-bcac2e228fab ; http://resolver.tudelft.nl/uuid:6840c5ea-824e-4d35-abc3-bcac2e228fab

Subjects/Keywords: computational fluid dynamics; domain decomposition

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Brakkee, E. (1996). Domain decomposition for the incompressible Navier-Stokes equations. (Doctoral Dissertation). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:6840c5ea-824e-4d35-abc3-bcac2e228fab ; urn:NBN:nl:ui:24-uuid:6840c5ea-824e-4d35-abc3-bcac2e228fab ; urn:NBN:nl:ui:24-uuid:6840c5ea-824e-4d35-abc3-bcac2e228fab ; http://resolver.tudelft.nl/uuid:6840c5ea-824e-4d35-abc3-bcac2e228fab

Chicago Manual of Style (16^th Edition):

Brakkee, E. “Domain decomposition for the incompressible Navier-Stokes equations.” 1996. Doctoral Dissertation, Delft University of Technology. Accessed February 27, 2021. http://resolver.tudelft.nl/uuid:6840c5ea-824e-4d35-abc3-bcac2e228fab ; urn:NBN:nl:ui:24-uuid:6840c5ea-824e-4d35-abc3-bcac2e228fab ; urn:NBN:nl:ui:24-uuid:6840c5ea-824e-4d35-abc3-bcac2e228fab ; http://resolver.tudelft.nl/uuid:6840c5ea-824e-4d35-abc3-bcac2e228fab.

MLA Handbook (7^th Edition):

Brakkee, E. “Domain decomposition for the incompressible Navier-Stokes equations.” 1996. Web. 27 Feb 2021.

Vancouver:

Brakkee E. Domain decomposition for the incompressible Navier-Stokes equations. [Internet] [Doctoral dissertation]. Delft University of Technology; 1996. [cited 2021 Feb 27]. Available from: http://resolver.tudelft.nl/uuid:6840c5ea-824e-4d35-abc3-bcac2e228fab ; urn:NBN:nl:ui:24-uuid:6840c5ea-824e-4d35-abc3-bcac2e228fab ; urn:NBN:nl:ui:24-uuid:6840c5ea-824e-4d35-abc3-bcac2e228fab ; http://resolver.tudelft.nl/uuid:6840c5ea-824e-4d35-abc3-bcac2e228fab.

Council of Science Editors:

Brakkee E. Domain decomposition for the incompressible Navier-Stokes equations. [Doctoral Dissertation]. Delft University of Technology; 1996. Available from: http://resolver.tudelft.nl/uuid:6840c5ea-824e-4d35-abc3-bcac2e228fab ; urn:NBN:nl:ui:24-uuid:6840c5ea-824e-4d35-abc3-bcac2e228fab ; urn:NBN:nl:ui:24-uuid:6840c5ea-824e-4d35-abc3-bcac2e228fab ; http://resolver.tudelft.nl/uuid:6840c5ea-824e-4d35-abc3-bcac2e228fab

Delft University of Technology

16. Ram, Raju (author). Parallel Deflated CG Method to Model Groundwater Flow in a Layered Grid.

Degree: 2017, Delft University of Technology

URL: http://resolver.tudelft.nl/uuid:ac750cb3-eb56-405e-89c4-2c9c1c5937dd

►

Groundwater, present beneath the earth’s surface in soil pore spaces, is the primary source of fresh water that we use in day to day life.… (more)

Subjects/Keywords: Sparse Solvers; Domain Decomposition; Deflation Preconditioning; Linear Deflation Vectors

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Ram, R. (. (2017). Parallel Deflated CG Method to Model Groundwater Flow in a Layered Grid. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:ac750cb3-eb56-405e-89c4-2c9c1c5937dd

Chicago Manual of Style (16^th Edition):

Ram, Raju (author). “Parallel Deflated CG Method to Model Groundwater Flow in a Layered Grid.” 2017. Masters Thesis, Delft University of Technology. Accessed February 27, 2021. http://resolver.tudelft.nl/uuid:ac750cb3-eb56-405e-89c4-2c9c1c5937dd.

MLA Handbook (7^th Edition):

Ram, Raju (author). “Parallel Deflated CG Method to Model Groundwater Flow in a Layered Grid.” 2017. Web. 27 Feb 2021.

Vancouver:

Ram R(. Parallel Deflated CG Method to Model Groundwater Flow in a Layered Grid. [Internet] [Masters thesis]. Delft University of Technology; 2017. [cited 2021 Feb 27]. Available from: http://resolver.tudelft.nl/uuid:ac750cb3-eb56-405e-89c4-2c9c1c5937dd.

Council of Science Editors:

Ram R(. Parallel Deflated CG Method to Model Groundwater Flow in a Layered Grid. [Masters Thesis]. Delft University of Technology; 2017. Available from: http://resolver.tudelft.nl/uuid:ac750cb3-eb56-405e-89c4-2c9c1c5937dd

University of Minnesota

17. Kalantzis, Vasileios. Domain decomposition algorithms for the solution of sparse symmetric generalized eigenvalue problems.

Degree: PhD, Computer Science, 2018, University of Minnesota

URL: http://hdl.handle.net/11299/201170

► This dissertation focuses on the design, implementation, and evaluation of domain decomposition techniques for the solution of large and sparse algebraic symmetric generalized eigenvalue problems.… (more)

▼ This dissertation focuses on the design, implementation, and evaluation of domain decomposition techniques for the solution of large and sparse algebraic symmetric generalized eigenvalue problems. Domain decomposition techniques begin by partitioning the global (discretized) domain into a number of subdomains. The solution of the algebraic eigenvalue problem is then decoupled into two separate subproblems: (1) one defined locally in the interior of each subdomain, and (2) one defined on the interface region connecting neighboring subdomains. As soon as the part of the solution associated with the interface region is computed, the part of the solution associated with the interior variables in each subdomain can be computed locally and independently of the rest of the subdomains. The domain decomposition techniques proposed in this dissertation can be classified into two categories: (1) filtering techniques, and (2) root-finding techniques. Filtering techniques are projection methods applied to a transformation of the original matrix pencil chosen so that, ideally, the eigenvalues of interest are mapped to the only nonzero eigenvalues in the transformed pencil. This dissertation combines domain decomposition with filtering approaches and demonstrates how this class of hybrid algorithms can outperform current state-of-the-art filtering techniques. Apart being well-suited for execution on distributed memory systems, an immediate advantage of such hybrid techniques is that any orthogonalization necessary needs to be performed only to vectors whose length is equal to the number of interface variables. Moreover, we show that if the filter is applied only to that portion of the pencil associated with the interface variables, it is possible to even achieve convergence within a number of steps that is smaller than the number of eigenvalues located inside the interval of interest. In contrast, any projection method applied to a transformation of the original matrix pencil must perform a number of steps that is at least equal to the number of eigenvalues located inside the interval of interest. Implementation aspects of the proposed numerical schemes on many-core/multi-core computer systems and experiments on serial/distributed computing environments are also discussed. Root-finding techniques convert the interface eigenvalue problem into one of computing roots of scalar functions, i.e., the eigenvalues of the original eigenvalue problem are roots of a carefully chosen scalar function. This allows the use of existing fast iterative root-finding schemes, e.g. Newton's method, for the solution of symmetric generalized eigenvalue problems. Root-finding techniques can be especially useful when only a few eigenvalues and associated eigenvectors are sought. The numerical schemes proposed in this part of the present dissertation are compared against other single-vector eigenvalue solvers such as the Rayleigh Quotient Iteration and Residual Inverse Iteration. Numerous theoretical details and practical…

Subjects/Keywords: Domain decomposition; Eigenvalues; Schur complement; Sparse matrices; Symmetric generalized eigenvalue problem

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Kalantzis, V. (2018). Domain decomposition algorithms for the solution of sparse symmetric generalized eigenvalue problems. (Doctoral Dissertation). University of Minnesota. Retrieved from http://hdl.handle.net/11299/201170

Chicago Manual of Style (16^th Edition):

Kalantzis, Vasileios. “Domain decomposition algorithms for the solution of sparse symmetric generalized eigenvalue problems.” 2018. Doctoral Dissertation, University of Minnesota. Accessed February 27, 2021. http://hdl.handle.net/11299/201170.

MLA Handbook (7^th Edition):

Kalantzis, Vasileios. “Domain decomposition algorithms for the solution of sparse symmetric generalized eigenvalue problems.” 2018. Web. 27 Feb 2021.

Vancouver:

Kalantzis V. Domain decomposition algorithms for the solution of sparse symmetric generalized eigenvalue problems. [Internet] [Doctoral dissertation]. University of Minnesota; 2018. [cited 2021 Feb 27]. Available from: http://hdl.handle.net/11299/201170.

Council of Science Editors:

Kalantzis V. Domain decomposition algorithms for the solution of sparse symmetric generalized eigenvalue problems. [Doctoral Dissertation]. University of Minnesota; 2018. Available from: http://hdl.handle.net/11299/201170

University of Manchester

18. Jones, Adam. Development of a near-wall domain decomposition method for turbulent flows.

Degree: 2016, University of Manchester

URL: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:297452

► In computational fluid dynamics (CFD), there are two widely-used methods for computing thenear-wall regions of turbulent flows: high Reynolds number (HRN) models and low Reynoldsnumber… (more)

▼ In computational fluid dynamics (CFD), there are two widely-used methods for computing thenear-wall regions of turbulent flows: high Reynolds number (HRN) models and low Reynoldsnumber (LRN) models. HRN models do not resolve the near-wall region, but instead use wallfunctions to compute the required parameters over the near-wall region. In contrast, LRNmodels resolve the flow right down to the wall. Simulations with HRN models can take anorder of magnitude less time than with LRN models, however the accuracy of the solution isreduced and certain requirements on the mesh must be met if the wall function is to be valid.It is often difficult or impossible to satisfy these requirements in industrial computations.In this thesis the near-wall domain decomposition (NDD) method of Utyuzhnikov (2006)is developed and implemented into the industrial code, Code_Saturne, for the first time.With the NDD approach, the near-wall regions of a fluid flow are removed from the maincomputational mesh. Instead, the mesh extends down to an interface boundary, which islocated a short distance from the wall, denoted y*. A simplified boundary layer equation isused to calculate boundary conditions at the interface. When implemented with a turbulencemodel which can resolve down to the wall, there is no lower limit on the value of y*. Thereis a Reynolds number-dependent upper limit on y*, as there is with HRN models. Thus forlarge y*, the model functions as a HRN model and as y*→ 0 the LRN solution is recovered.NDD is implemented for the k−ε and Spalart-Allmaras turbulence models and is testedon five test cases: a channel flow at two different Reynolds numbers, an annular flow, animpinging jet flow and the flow in an asymmetric diffuser. The method is tested as a HRNand LRN model and it is found that the method behaves competitively with the scalable wallfunction (SWF) on simpler flows, and performs better on the asymmetric diffuser flow, wherethe NDD solution correctly captures the recirculation region whereas the SWF does not.The method is then tested on a ribbed channel flow. Particular focus is given to investigatinghow much of the rib can be excluded from the main computational mesh. It is found that itis possible to remove 90% of the rib from the mesh with less than 2% error in the frictionfactor compared to the LRN solution.The thesis then focuses on the industrial case of the flow in an annulus where the inner wall,referred to as the pin, has a rib on its surface that protrudes into the annulus. Comparisonis made between CFD calculations, experimental data and empirical correlations. It is foundthat the experimental friction factors are significantly larger than those found with CFD,and that the trend in the friction factor with Reynolds number found in the experiments isdifferent. Simulations are performed to quantify the effect that a non-smooth surface finishon the pin and rib surface has on the flow. This models the situation that occurs in anadvanced gas-cooled nuclear reactor, when a carbon deposit forms on the fuel pins.… Advisors/Committee Members: LAURENCE, DOMINIQUE DRP, Utyuzhnikov, Sergey, Laurence, Dominique.

Subjects/Keywords: AGR; Domain decomposition; Code Saturne; Wall functions; RANS

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Jones, A. (2016). Development of a near-wall domain decomposition method for turbulent flows. (Doctoral Dissertation). University of Manchester. Retrieved from http://www.manchester.ac.uk/escholar/uk-ac-man-scw:297452

Chicago Manual of Style (16^th Edition):

Jones, Adam. “Development of a near-wall domain decomposition method for turbulent flows.” 2016. Doctoral Dissertation, University of Manchester. Accessed February 27, 2021. http://www.manchester.ac.uk/escholar/uk-ac-man-scw:297452.

MLA Handbook (7^th Edition):

Jones, Adam. “Development of a near-wall domain decomposition method for turbulent flows.” 2016. Web. 27 Feb 2021.

Vancouver:

Jones A. Development of a near-wall domain decomposition method for turbulent flows. [Internet] [Doctoral dissertation]. University of Manchester; 2016. [cited 2021 Feb 27]. Available from: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:297452.

Council of Science Editors:

Jones A. Development of a near-wall domain decomposition method for turbulent flows. [Doctoral Dissertation]. University of Manchester; 2016. Available from: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:297452

University of Texas – Austin

19. -5494-1880. Fast and scalable solvers for high-order hybridized discontinuous Galerkin methods with applications to fluid dynamics and magnetohydrodynamics.

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

URL: http://dx.doi.org/10.26153/tsw/5474

► The hybridized discontinuous Galerkin methods (HDG) introduced a decade ago is a promising candidate for high-order spatial discretization combined with implicit/implicit-explicit time stepping. Roughly speaking,… (more)

▼ The hybridized discontinuous Galerkin methods (HDG) introduced a decade ago is a promising candidate for high-order spatial discretization combined with implicit/implicit-explicit time stepping. Roughly speaking, HDG methods combines the advantages of both discontinuous Galerkin (DG) methods and hybridized methods. In particular, it enjoys the benefits of equal order spaces, upwinding and ability to handle large gradients of DG methods as well as the smaller globally coupled linear system, adaptivity, and multinumeric capabilities of hybridized methods. However, the main bottleneck in HDG methods, limiting its use to small to moderate sized problems, is the lack of scalable linear solvers. In this thesis we develop fast and scalable solvers for HDG methods consisting of domain decomposition, multigrid and multilevel solvers/preconditioners with an ultimate focus on simulating large scale problems in fluid dynamics and magnetohydrodynamics (MHD). First, we propose a domain decomposition based solver namely iterative HDG for partial differential equations (PDEs). It is a fixed point iterative scheme, with each iteration consisting only of element-by-element and face-by-face embarrassingly parallel solves. Using energy analysis we prove the convergence of the schemes for scalar and system of hyperbolic PDEs and verify the results numerically. We then propose a novel geometric multigrid approach for HDG methods based on fine scale Dirichlet-to-Neumann maps. The algorithm combines the robustness of algebraic multigrid methods due to operator dependent intergrid transfer operators and at the same time has fixed coarse grid construction costs due to its geometric nature. For diffusion dominated PDEs such as the Poisson and the Stokes equations the algorithm gives almost perfect hp – scalability. Next, we propose a multilevel algorithm by combining the concepts of nested dissection, a fill-in reducing ordering strategy, variational structure and high-order properties of HDG, and domain decomposition. Thanks to its root in direct solver strategy the performance of the solver is almost independent of the nature of the PDEs and mostly depends on the smoothness of the solution. We demonstrate this numerically with several prototypical PDEs. Finally, we propose a block preconditioning strategy for HDG applied to incompressible visco-resistive MHD. We use a least squares commutator approximation for the inverse of the Schur complement and algebraic multigrid or the multilevel preconditioner for the approximate inverse of the nodal block. With several 2D and 3D transient examples we demonstrate the robustness and parallel scalability of the block preconditioner Advisors/Committee Members: Bui-Thanh, Tan (advisor), Demkowicz, Leszek F (committee member), Ghattas, Omar (committee member), Raja, Laxminarayan L (committee member), Shadid, John N (committee member), Waelbroeck, Francois L (committee member), Wheeler, Mary F (committee member).

Subjects/Keywords: Hybridized discontinuous Galerkin; Fast solvers; Multigrid; Multilevel; MHD; Domain decomposition

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

-5494-1880. (2019). Fast and scalable solvers for high-order hybridized discontinuous Galerkin methods with applications to fluid dynamics and magnetohydrodynamics. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://dx.doi.org/10.26153/tsw/5474

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

Chicago Manual of Style (16^th Edition):

-5494-1880. “Fast and scalable solvers for high-order hybridized discontinuous Galerkin methods with applications to fluid dynamics and magnetohydrodynamics.” 2019. Doctoral Dissertation, University of Texas – Austin. Accessed February 27, 2021. http://dx.doi.org/10.26153/tsw/5474.

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

MLA Handbook (7^th Edition):

-5494-1880. “Fast and scalable solvers for high-order hybridized discontinuous Galerkin methods with applications to fluid dynamics and magnetohydrodynamics.” 2019. Web. 27 Feb 2021.

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

Vancouver:

-5494-1880. Fast and scalable solvers for high-order hybridized discontinuous Galerkin methods with applications to fluid dynamics and magnetohydrodynamics. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2019. [cited 2021 Feb 27]. Available from: http://dx.doi.org/10.26153/tsw/5474.

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

Council of Science Editors:

-5494-1880. Fast and scalable solvers for high-order hybridized discontinuous Galerkin methods with applications to fluid dynamics and magnetohydrodynamics. [Doctoral Dissertation]. University of Texas – Austin; 2019. Available from: http://dx.doi.org/10.26153/tsw/5474

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

University of Texas – Austin

20. -3203-266X. Numerical algorithms based on Galerkin methods for the modeling of reactive interfaces in photoelectrochemical solar cells.

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

URL: http://hdl.handle.net/2152/46973

► Large-scale utilization of photovoltaic (PV) devices, or solar cells, has been hampered for years due to high costs and lack of energy storage mechanisms. Photoelectrochemical… (more)

▼ Large-scale utilization of photovoltaic (PV) devices, or solar cells, has been hampered for years due to high costs and lack of energy storage mechanisms. Photoelectrochemical solar cells (PECs) are an attractive alternative to conventional solid state PV devices because they are able to directly convert solar energy into hydrogen fuel. The hydrogen fuel can then be used at a later time to generate electricity. Photoelectrochemical solar cells are able to produce fuel through chemical reactions at the interface of a semiconductor and electrolyte when the device is illuminated. In this dissertation, we focus on the modeling and numerical simulation of charge transport in both the semiconductor and electrolyte region as well as their interaction through a reactive interface using the drift-diffusion-Poisson equations. The main challenges in constructing a numerical algorithm that produces reliable simulations of PECs are due to the highly nonlinear nature of the semiconductor and electrolyte systems as well as the nonlinear coupling between the two systems at the interface. In addition, the evolution problem under consideration is effectively multi-scale in the sense that the evolution of the system in the semiconductor and the corresponding one in the electrolyte evolve at different time scales due to the quantitative scaling differences in their relevant physical parameters. Furthermore, regions of stiffness caused by boundary layer formation where sharp transitions in densities and electric potential occur near the interface and pose severe constraints on the choice of discretization strategy in order to maintain numerical stability. In this thesis we propose, implement and analyze novel numerical algorithms for the simulation of photoelectrochemical solar cells. Spatial discetizations of the drift-diffusion-Poisson equations are based on mixed finite element methods and local discontinuous Galerkin methods. To alleviate the stiffness of the equations we develop and analyze Schwarz domain decomposition methods in conjunction with implicit-explicit (IMEX) time stepping routines. We analyze the numerical methods and prove their convergence under mesh refinement. Finally, we present results from numerical experiments in order to develop a strategy for optimizing solar cell design at the nano-scale. Advisors/Committee Members: Martínez Gamba, Irene, 1957- (advisor), Ren, Kui (advisor), Dawson, Clint (committee member), Ghattas, Omar (committee member), Henkelman, Graeme (committee member).

Subjects/Keywords: Discontinuous Galerkin methods; Mixed methods; Domain decomposition methods; Solar cells

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

-3203-266X. (2016). Numerical algorithms based on Galerkin methods for the modeling of reactive interfaces in photoelectrochemical solar cells. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/46973

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

Chicago Manual of Style (16^th Edition):

-3203-266X. “Numerical algorithms based on Galerkin methods for the modeling of reactive interfaces in photoelectrochemical solar cells.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed February 27, 2021. http://hdl.handle.net/2152/46973.

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

MLA Handbook (7^th Edition):

-3203-266X. “Numerical algorithms based on Galerkin methods for the modeling of reactive interfaces in photoelectrochemical solar cells.” 2016. Web. 27 Feb 2021.

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

Vancouver:

-3203-266X. Numerical algorithms based on Galerkin methods for the modeling of reactive interfaces in photoelectrochemical solar cells. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Feb 27]. Available from: http://hdl.handle.net/2152/46973.

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

Council of Science Editors:

-3203-266X. Numerical algorithms based on Galerkin methods for the modeling of reactive interfaces in photoelectrochemical solar cells. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/46973

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

The Ohio State University

21. Wu, Xiaofeng. Reduced Deformable Body Simulation with Richer Dynamics.

Degree: PhD, Computer Science and Engineering, 2016, The Ohio State University

URL: http://rave.ohiolink.edu/etdc/view?acc_num=osu1471482167

► Deformable body simulation can provide visually interesting results that have wide applications in both entertainment industries and scientific fields. However, it is computationally demanding when… (more)

▼ Deformable body simulation can provide visually interesting results that have wide applications in both entertainment industries and scientific fields. However, it is computationally demanding when simulating detailed models with high degrees of freedom (DoFs). Subspace simulation is known for its ability to significantly accelerate the simulation by constraining the deformation of the model to lie within a prescribed low-dimensional space so that the high-DoFs dynamic system is reduced to a much lower one. State-of-the-art subspace simulation technique only allows around 100 simulation bases to be used for real-time applications. This limitation causes many interesting deformations results to be lost or even leads to deformation artifacts. In this dissertation, we focus on developing new techniques that empower subspace simulation to capture richer deformation dynamics. First, we propose a unified approach for simulating reduced multi-domain objects, where each domain of the object is simulated in its own subspace. The key challenge in implementing this method is how to handle the coupling among multiple deformable do- mains, so that the overall effect is free of gap or locking issues. We present a new domain decomposition framework that connects two disjoint domains through coupling elements. Under this framework, we present a unified simulation system that solves subspace deformations and rigid motions of all of the domains by a single linear solve. Since the coupling elements are part of the deformable body, their elastic properties are the same as the rest of the body and our system does not need stiffness parameter tuning. To quickly evaluate the reduced elastic forces and their Jacobian matrices caused by the coupling elements, we further develop two cubature optimization schemes using uniform and non-uniform cubature weights. Our experiment shows that the whole system can efficiently handle large and complex scenes, many of which cannot be easily simulated by previous techniques without limitations. Second, we designed a novel single-domain subspace solver that is superior to previous methods in terms of theoretical time complexity, actual running time and GPU implementation efficiency. Inspired by the recently proposed Projective Dynamics (PD) framework that makes use of a constant approximate Hessian for simulation, we proposed a new sub- space solver that utilizes BFGS’s self-correcting property to directly approximate the in- verse of the Hessian. Thus, GPU-unfriendly linear solve can be avoided. Moreover, our method does not require the expensive run-time evaluation of Hessian, which we identify as the bottleneck of existing subspace solver and is not GPU implementation friendly either. We designed experiments to show that our subspace solver can achieve several orders- of-magnitude speedup and much better scalability w.r.t. number of simulation bases over existing method. Advisors/Committee Members: Wang, Huamin (Advisor).

Subjects/Keywords: Computer Science; deformable body simulation; model reduction; subspace simulation; domain decomposition

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Wu, X. (2016). Reduced Deformable Body Simulation with Richer Dynamics. (Doctoral Dissertation). The Ohio State University. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=osu1471482167

Chicago Manual of Style (16^th Edition):

Wu, Xiaofeng. “Reduced Deformable Body Simulation with Richer Dynamics.” 2016. Doctoral Dissertation, The Ohio State University. Accessed February 27, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1471482167.

MLA Handbook (7^th Edition):

Wu, Xiaofeng. “Reduced Deformable Body Simulation with Richer Dynamics.” 2016. Web. 27 Feb 2021.

Vancouver:

Wu X. Reduced Deformable Body Simulation with Richer Dynamics. [Internet] [Doctoral dissertation]. The Ohio State University; 2016. [cited 2021 Feb 27]. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1471482167.

Council of Science Editors:

Wu X. Reduced Deformable Body Simulation with Richer Dynamics. [Doctoral Dissertation]. The Ohio State University; 2016. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1471482167

New Jersey Institute of Technology

22. Qi, Haiyang. Boundary integral equation based numerical solutions of helmholtz transmission problems for composite scatters.

Degree: PhD, Mathematical Sciences, 2017, New Jersey Institute of Technology

URL: https://digitalcommons.njit.edu/dissertations/38

► In this dissertation, an in-depth comparison between boundary integral equation solvers and Domain Decomposition Methods (DDM) for frequency domain Helmholtz transmission problems in composite… (more)

▼ In this dissertation, an in-depth comparison between boundary integral equation solvers and Domain Decomposition Methods (DDM) for frequency domain Helmholtz transmission problems in composite two-dimensional media is presented. Composite media are characterized by piece-wise constant material properties (i.e., index of refraction) and thus, they exhibit interfaces of material discontinuity and multiple junctions. Whenever possible to use, boundary integral methods for solution of Helmholtz boundary value problems are computationally advantageous. Indeed, in addition to the dimensional reduction and straightforward enforcement of the radiation conditions that these methods enjoy, they do not suffer from the pollution effect present in volumetric discretization. The reformulation of Helmholtz transmission problems in composite media in terms of boundary integral equations via multi-traces constitutes one of the recent success stories in the boundary integral equation community. Multi-trace formulations (MTF) incorporate local Dirichlet and Neumann traces on subdomains within Green’s identities and use restriction and extension by zero operators to enforce the intradomain continuity of the fields and fluxes. Through usage of subdomain Calderon projectors, the transmission problem is cast into a linear system form whose unknowns are local Dirichlet and Neumann traces (two such traces per interface of material discontinuity) and whose operator matrix consists of diagonal block boundary integral operators associated with the subdomains and extension/projections off diagonal blocks. This particular form of the matrix operator associated with MTF is amenable to operator preconditioning via Calderon projectors. DDM rely on subdomain solutions that are matched via transmission conditions on the subdomain interfaces that are equivalent to the physical continuity of fields and traces. By choosing the appropriate transmission conditions, the convergence of DDM for frequency domain scattering problems can be accelerated. Traditionally, the intradomain transmission conditions were chosen to be the classical outgoing Robin/impedance boundary conditions. When the ensuing DDM linear system is solved via Krylov subspace methods, the convergence of DDM with classical Robin transmission conditions is slow and adversely affected by the number of subdomains. Heuristically, this behavior is explained by the fact that Robin boundary conditions are first order approximations of transparent boundary conditions, and thus there is significant information that is reflected back into a given subdomain from adjacent subdomains. Clearly, using more sophisticated transparent boundary conditions facilitates the information exchange between subdomains. For instance, Dirichlet-to-Neumann (DtN) operators of adjacent domains or suitable approximations of these can be used in the form of generalized Robin boundary conditions to increase the rate of the convergence of iterative solvers of DDM linear systems.… Advisors/Committee Members: Catalin C. Turc, Michael Siegel, Eliza Zoi-Heleni Michalopoulou.

Subjects/Keywords: Helmholtz transmission problem; Boundary integral equation; Domain decomposition method; Mathematics

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Qi, H. (2017). Boundary integral equation based numerical solutions of helmholtz transmission problems for composite scatters. (Doctoral Dissertation). New Jersey Institute of Technology. Retrieved from https://digitalcommons.njit.edu/dissertations/38

Chicago Manual of Style (16^th Edition):

Qi, Haiyang. “Boundary integral equation based numerical solutions of helmholtz transmission problems for composite scatters.” 2017. Doctoral Dissertation, New Jersey Institute of Technology. Accessed February 27, 2021. https://digitalcommons.njit.edu/dissertations/38.

MLA Handbook (7^th Edition):

Qi, Haiyang. “Boundary integral equation based numerical solutions of helmholtz transmission problems for composite scatters.” 2017. Web. 27 Feb 2021.

Vancouver:

Qi H. Boundary integral equation based numerical solutions of helmholtz transmission problems for composite scatters. [Internet] [Doctoral dissertation]. New Jersey Institute of Technology; 2017. [cited 2021 Feb 27]. Available from: https://digitalcommons.njit.edu/dissertations/38.

Council of Science Editors:

Qi H. Boundary integral equation based numerical solutions of helmholtz transmission problems for composite scatters. [Doctoral Dissertation]. New Jersey Institute of Technology; 2017. Available from: https://digitalcommons.njit.edu/dissertations/38

New Jersey Institute of Technology

23. Pedneault, Michael. Domain decomposition methods for the solution of multiple scattering problems.

Degree: PhD, Mathematical Sciences, 2018, New Jersey Institute of Technology

URL: https://digitalcommons.njit.edu/dissertations/1390

► This presents a Schur complement Domain Decomposition (DD) algorithm for the solution of frequency domain multiple scattering problems. Just as in the classical DD… (more)

Subjects/Keywords: Acoustic scattering; Domain decomposition; Integral equations; Multiple scattering; Mathematics

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Pedneault, M. (2018). Domain decomposition methods for the solution of multiple scattering problems. (Doctoral Dissertation). New Jersey Institute of Technology. Retrieved from https://digitalcommons.njit.edu/dissertations/1390

Chicago Manual of Style (16^th Edition):

Pedneault, Michael. “Domain decomposition methods for the solution of multiple scattering problems.” 2018. Doctoral Dissertation, New Jersey Institute of Technology. Accessed February 27, 2021. https://digitalcommons.njit.edu/dissertations/1390.

MLA Handbook (7^th Edition):

Pedneault, Michael. “Domain decomposition methods for the solution of multiple scattering problems.” 2018. Web. 27 Feb 2021.

Vancouver:

Pedneault M. Domain decomposition methods for the solution of multiple scattering problems. [Internet] [Doctoral dissertation]. New Jersey Institute of Technology; 2018. [cited 2021 Feb 27]. Available from: https://digitalcommons.njit.edu/dissertations/1390.

Council of Science Editors:

Pedneault M. Domain decomposition methods for the solution of multiple scattering problems. [Doctoral Dissertation]. New Jersey Institute of Technology; 2018. Available from: https://digitalcommons.njit.edu/dissertations/1390

University of Colorado

24. 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

Record Details Similar Records Cite « Share

❌

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 February 27, 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. 27 Feb 2021.

Vancouver:

Mitchell WB. Low-Communication, Parallel Multigrid Algorithms for Elliptic Partial Differential Equations. [Internet] [Doctoral dissertation]. University of Colorado; 2017. [cited 2021 Feb 27]. 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

Stellenbosch University

25. Ludick, Daniel Jacobus. Efficient numerical analysis of finite antenna arrays using domain decomposition methods.

Degree: PhD, 2014, Stellenbosch University

URL: http://hdl.handle.net/10019.1/96124

►

ENGLISH ABSTRACT: This work considers the efficient numerical analysis of large, aperiodic finite antenna arrays. A Method of Moments (MoM) based domain decomposition technique called… (more)

▼

ENGLISH ABSTRACT: This work considers the efficient numerical analysis of large, aperiodic finite antenna arrays. A Method of Moments (MoM) based domain decomposition technique called the Domain Green's Function Method (DGFM) is formulated to address a wide range of array problems in a memory and runtime efficient manner. The DGFM is a perturbation approach that builds on work initially conducted by Skrivervik and Mosig for disjoint arrays on multi-layered substrates, a detailed review of which will be provided in this thesis. Novel extensions considered for the DGFM are as follows: a formulation on a higher block matrix factorisation level that allows for the treatment of a wider range of applications, and is essentially independent of the elemental basis functions used for the MoM matrix formulation of the problem. As an example of this, both conventional Rao-Wilton-Glisson elements and also hierarchical higher order basis functions were used to model large array structures. Acceleration techniques have been developed for calculating the impedance matrix for large arrays including one based on using the Adaptive Cross Approximation (ACA) algorithm. Accuracy improvements that extend the initial perturbation assumption on which the method is based have also been formulated. Finally, the DGFM is applied to array geometries in complex environments, such as that in the presence of finite ground planes, by using the Numerical Green's Function (NGF) method in the hybrid NGF-DGFM formulation. In addition to the above, the DGFM is combined with the existing domain decomposition method, viz., the Characteristic Basis Function Method (CBFM), to be used for the analysis of very large arrays consisting of sub-array tiles, such as the Low-Frequency Array (LOFAR) for radio astronomy. Finally, interesting numerical applications for the DGFM are presented, in particular their usefulness for the electromagnetic analysis of large, aperiodic sparse arrays. For this part, the accuracy improvements of the DGFM are used to calculate quantities such as embedded element patterns, which is a major extension from its original formulation. The DGFM has been integrated as part of an efficient array analysis tool in the commercial computational electromagnetics software package, FEKO.

AFRIKAANSE OPSOMMING: In hierdie werkstuk word die doeltre ende analise van eindige, aperiodiese antenna samestellings behandel. Eindige gebied benaderings wat op die Moment Metode (MoM) berus, word as vetrekpunt gebruik. `n Tegniek genaamd die Gebied Green's Funksie Metode (GGFM) word voorgestel en is geskik vir die analise van `n verskeidenheid van ontkoppelde samestellings. Die e ektiewe gebruik van rekenaargeheue en looptyd is onderliggend in die implementasie daarvan. Die GGFM is 'n perturbasie metode wat op die oorspronklike werk van Skrivervik en Mosig berus. Laasgenoemde is hoofsaaklik ontwikkel vir die analise van ontkoppelde antenna samestellings op multilaag di elektrikums. `n Deeglike oorsig van voorafgaande word in…

Advisors/Committee Members: Davidson, David B., Jakobus, U., Stellenbosch University. Faculty of Engineering. Department of Electrical and Electronic Engineering..

Subjects/Keywords: Moments method (Statistics); Domain decomposition; Antenna arrays; Characteristic basis function method; Domain Green's function method (DGFM); UCTD

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Ludick, D. J. (2014). Efficient numerical analysis of finite antenna arrays using domain decomposition methods. (Doctoral Dissertation). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/96124

Chicago Manual of Style (16^th Edition):

Ludick, Daniel Jacobus. “Efficient numerical analysis of finite antenna arrays using domain decomposition methods.” 2014. Doctoral Dissertation, Stellenbosch University. Accessed February 27, 2021. http://hdl.handle.net/10019.1/96124.

MLA Handbook (7^th Edition):

Ludick, Daniel Jacobus. “Efficient numerical analysis of finite antenna arrays using domain decomposition methods.” 2014. Web. 27 Feb 2021.

Vancouver:

Ludick DJ. Efficient numerical analysis of finite antenna arrays using domain decomposition methods. [Internet] [Doctoral dissertation]. Stellenbosch University; 2014. [cited 2021 Feb 27]. Available from: http://hdl.handle.net/10019.1/96124.

Council of Science Editors:

Ludick DJ. Efficient numerical analysis of finite antenna arrays using domain decomposition methods. [Doctoral Dissertation]. Stellenbosch University; 2014. Available from: http://hdl.handle.net/10019.1/96124

26. Linel, Patrice. Méthodes de décomposition de domaines en temps et en espace pour la résolution de systèmes d’EDOs non-linéaires : Time and space domain decomposition method for nonlinear ODE.

Degree: Docteur es, Mathématiques appliquées, 2011, Université Claude Bernard – Lyon I

URL: http://www.theses.fr/2011LYO10102

►

La complexification de la modélisation multi-physique conduit d’une part à devoir simuler des systèmes d’équations différentielles ordinaires et d’équations différentielles algébriques de plus en plus… (more)

▼

La complexification de la modélisation multi-physique conduit d’une part à devoir simuler des systèmes d’équations différentielles ordinaires et d’équations différentielles algébriques de plus en plus grands en nombre d’inconnues et sur des temps de simulation longs. D’autre part l’évolution des architectures de calcul parallèle nécessite d’autres voies de parallélisation que la décomposition de système en sous-systèmes. Dans ce travail, nous proposons de concevoir des méthodes de décomposition de domaine pour la résolution d’EDO en temps. Nous reformulons le problème à valeur initiale en un problème aux valeurs frontières sur l’intervalle de temps symétrisé, sous l’hypothèse de réversibilité du flot. Nous développons deux méthodes, la première apparentée à une méthode de complément de Schur, la seconde basée sur une méthode de type Schwarz dont nous montrons la convergence pouvant être accélérée par la méthode d’Aitken dans le cadre linéaire. Afin d’accélérer la convergence de cette dernière dans le cadre non-linéaire, nous introduisons les techniques d’extrapolation et d’accélération de la convergence des suites non-linéaires. Nous montrons les avantages et les limites de ces techniques. Les résultats obtenus nous conduisent à développer l’accélération de la méthode de type Schwarz par une méthode de Newton. Enfin nous nous intéressons à l’étude de conditions de raccord non-linéaires adaptées à la décomposition de domaine de problèmes non-linéaires. Nous nous servons du formalisme hamiltonien à ports, issu du domaine de l’automatique, pour déduire les conditions de raccord dans le cadre l’équation de Saint-Venant et de l’équation de la chaleur non-linéaire. Après une étude analytique de la convergence de la DDM associée à ces conditions de transmission, nous proposons et étudions une formulation de Lagrangien augmenté sous l’hypothèse de séparabilité de la contrainte.

Complexification of multi-physics modeling leads to have to simulate systems of ordinary differential equations and algebraic differential equations with increasingly large numbers of unknowns and over large times of simulation. In addition the evolution of parallel computing architectures requires other ways of parallelization than the decomposition of system in subsystems. In this work, we propose to design domain decomposition methods in time for the resolution of EDO. We reformulate the initial value problem in a boundary values problem on the symmetrized time interval, under the assumption of reversibility of the flow. We develop two methods, the first connected with a Schur complement method, the second based on a Schwarz type method for which we show convergence, being able to be accelerated by the Aitken method within the linear framework. In order to accelerate the convergence of the latter within the non-linear framework, we introduce the techniques of extrapolation and of acceleration of the convergence of non-linear sequences. We show the advantages and the limits of these techniques. The obtained results lead us to develop the…

Advisors/Committee Members: Lefèvre, Laurent (thesis director), Tromeur-Dervout, Damien (thesis director).

Subjects/Keywords: Complément de Schur; Décomposition de domaine en temps; Newton-Krylov; Parallélisation; Accélération non-linéaire; Condition interface; Domain decomposition; Schur complement; Time domain decomposition; Newton- Krylov; Parallelization; Nonlinear acceleration; Interface condition

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Linel, P. (2011). Méthodes de décomposition de domaines en temps et en espace pour la résolution de systèmes d’EDOs non-linéaires : Time and space domain decomposition method for nonlinear ODE. (Doctoral Dissertation). Université Claude Bernard – Lyon I. Retrieved from http://www.theses.fr/2011LYO10102

Chicago Manual of Style (16^th Edition):

Linel, Patrice. “Méthodes de décomposition de domaines en temps et en espace pour la résolution de systèmes d’EDOs non-linéaires : Time and space domain decomposition method for nonlinear ODE.” 2011. Doctoral Dissertation, Université Claude Bernard – Lyon I. Accessed February 27, 2021. http://www.theses.fr/2011LYO10102.

MLA Handbook (7^th Edition):

Linel, Patrice. “Méthodes de décomposition de domaines en temps et en espace pour la résolution de systèmes d’EDOs non-linéaires : Time and space domain decomposition method for nonlinear ODE.” 2011. Web. 27 Feb 2021.

Vancouver:

Linel P. Méthodes de décomposition de domaines en temps et en espace pour la résolution de systèmes d’EDOs non-linéaires : Time and space domain decomposition method for nonlinear ODE. [Internet] [Doctoral dissertation]. Université Claude Bernard – Lyon I; 2011. [cited 2021 Feb 27]. Available from: http://www.theses.fr/2011LYO10102.

Council of Science Editors:

Linel P. Méthodes de décomposition de domaines en temps et en espace pour la résolution de systèmes d’EDOs non-linéaires : Time and space domain decomposition method for nonlinear ODE. [Doctoral Dissertation]. Université Claude Bernard – Lyon I; 2011. Available from: http://www.theses.fr/2011LYO10102

University of California – San Diego

27. Taverniers, Soren Henri. Nonintrusive approaches for multiscale/multiphysics problems with random noise.

Degree: Engineering Sciences (Engineering Physics), 2016, University of California – San Diego

URL: http://www.escholarship.org/uc/item/4d36j09h

► A plethora of computational techniques have been developed for computing quantities of interest in “multiscale” and “multiphysics” problems combining processes occurring on a broad spatiotemporal… (more)

▼ A plethora of computational techniques have been developed for computing quantities of interest in “multiscale” and “multiphysics” problems combining processes occurring on a broad spatiotemporal range. However, a dearth exists in systematic studies of the impact of random fluctuations on the predictive ability and numerical properties of these algorithms. We consider two nonintrusive approaches for multiphysics problems with random noise: domain decomposition and stochastic collocation. A mass-conserving domain decomposition achieving tight Newton- or Picard-based coupling between linear diffusion equations, one having a Gaussian white-noise source term, reveals that Newton's iteration scales linearly with noise amplitude, while Picard's iteration may scale superlinearly. For a given solution error, fully-converged (``implicit'') coupling is more efficient than single-iteration (``explicit'') coupling at low noise strength; at high noise amplitudes, this remains true provided that the time interval between two subsequent implicit coupling communications is sufficiently long. A similar strategy using Jacobian-free Newton-Krylov iteration to solve a highly nonlinear, multiscale diffusion problem forced by a truncated Gaussian boundary noise shows that ensuring path-wise continuity of the state variable and its flux, as opposed to continuity in the mean, accurately propagates random fluctuations and correctly captures system dynamics. Implicit coupling is more efficient than explicit coupling at all coefficients of variation considered, and domain decomposition with path-wise implicit coupling resolves temporally correlated boundary fluctuations when the correlation time exceeds some multiple of an appropriately defined characteristic diffusion time. Application of stochastic collocation to estimate the energy deposition into a brain tumor via X-ray irradiation with parametric uncertainty reveals that the uncertain parameters' coefficients of variation may be amplified by the problem's nonlinearity to the extent that the predictive uncertainty in the energy deposition almost equals the prediction itself. Algorithm refinement for the Ginzburg-Landau equation (GLE) demonstrates the need for adding a coarse-scale random source term to correctly propagate fine-scale Ising fluctuations throughout the computational domain. A moment-based approach with Gaussian closure enabling direct computation of the state variable's statistical moments is shown to be an accurate, and potentially more efficient, alternative to numerical time integration of the system state. A statistically learned stochastic GLE exhibits optimal predictive capacity at a complexity that may differ from that of standard models in the literature. This approach enables data-driven computation of the coarse-scale noise term's amplitude.

Subjects/Keywords: Engineering; Applied mathematics; Physics; domain decomposition; multiphysics; multiscale; nonintrusive; stochastic collocation; stochastic noise

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Taverniers, S. H. (2016). Nonintrusive approaches for multiscale/multiphysics problems with random noise. (Thesis). University of California – San Diego. Retrieved from http://www.escholarship.org/uc/item/4d36j09h

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):

Taverniers, Soren Henri. “Nonintrusive approaches for multiscale/multiphysics problems with random noise.” 2016. Thesis, University of California – San Diego. Accessed February 27, 2021. http://www.escholarship.org/uc/item/4d36j09h.

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

MLA Handbook (7^th Edition):

Taverniers, Soren Henri. “Nonintrusive approaches for multiscale/multiphysics problems with random noise.” 2016. Web. 27 Feb 2021.

Vancouver:

Taverniers SH. Nonintrusive approaches for multiscale/multiphysics problems with random noise. [Internet] [Thesis]. University of California – San Diego; 2016. [cited 2021 Feb 27]. Available from: http://www.escholarship.org/uc/item/4d36j09h.

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

Council of Science Editors:

Taverniers SH. Nonintrusive approaches for multiscale/multiphysics problems with random noise. [Thesis]. University of California – San Diego; 2016. Available from: http://www.escholarship.org/uc/item/4d36j09h

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

University of Toronto

28. Zheng, Jason ZX. Block-based Adaptive Mesh Refinement Finite-volume Scheme for Hybrid Multi-block Meshes.

Degree: 2012, University of Toronto

URL: http://hdl.handle.net/1807/33623

►

A block-based adaptive mesh refinement (AMR) finite-volume scheme is developed for solution of hyperbolic conservation laws on two-dimensional hybrid multi-block meshes. A Godunov-type upwind finite-volume… (more)

Subjects/Keywords: upwind finite-volume methods; adaptive mesh refinement (AMR); block-based hybrid mesh; domain decomposition; 0538

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Zheng, J. Z. (2012). Block-based Adaptive Mesh Refinement Finite-volume Scheme for Hybrid Multi-block Meshes. (Masters Thesis). University of Toronto. Retrieved from http://hdl.handle.net/1807/33623

Chicago Manual of Style (16^th Edition):

Zheng, Jason ZX. “Block-based Adaptive Mesh Refinement Finite-volume Scheme for Hybrid Multi-block Meshes.” 2012. Masters Thesis, University of Toronto. Accessed February 27, 2021. http://hdl.handle.net/1807/33623.

MLA Handbook (7^th Edition):

Zheng, Jason ZX. “Block-based Adaptive Mesh Refinement Finite-volume Scheme for Hybrid Multi-block Meshes.” 2012. Web. 27 Feb 2021.

Vancouver:

Zheng JZ. Block-based Adaptive Mesh Refinement Finite-volume Scheme for Hybrid Multi-block Meshes. [Internet] [Masters thesis]. University of Toronto; 2012. [cited 2021 Feb 27]. Available from: http://hdl.handle.net/1807/33623.

Council of Science Editors:

Zheng JZ. Block-based Adaptive Mesh Refinement Finite-volume Scheme for Hybrid Multi-block Meshes. [Masters Thesis]. University of Toronto; 2012. Available from: http://hdl.handle.net/1807/33623

Université Montpellier II

29. Iceta, Damien. Simulation numérique de la dynamique des systèmes discrets par décomposition de domaine et application aux milieux granulaires : Numerical simulation of dynamic discrete systems with domain decomposition and application to granular media.

Degree: Docteur es, Mécanique, génie mécanique, génie civil, 2010, Université Montpellier II

URL: http://www.theses.fr/2010MON20056

►

Les besoins industriels en simulation numérique de milieux granulaires sont de plus en plus conséquents pour des systèmes de grande dimension. Le cas d'interactions entre… (more)

▼

Les besoins industriels en simulation numérique de milieux granulaires sont de plus en plus conséquents pour des systèmes de grande dimension. Le cas d'interactions entre grains de type contact unilatéral avec frottement présente des difficultés supplémentaires pour de telles simulations. Dans ce mémoire une approche par décomposition de domaine est proposée. Les méthodes de sous structuration ont été initialement développées pour des milieux continus généralement discrétisés en mécanique des solides en éléments finis. La plateforme LMGC90 (Logiciel de Mécanique Gérant le Contact en Fortran 90) constitue le cadre d'implantation d'algorithmes dédiés. Ainsi des algorithmes de décomposition de domaine, reposant sur les méthodes LArge Time Increment et Gauss Seidel Non Linéaire, adaptés à un système de type granulaire sont définis, implantés et comparés.Pour exploiter le potentiel en calcul parallèle des méthodes ci-dessus, les procédures d'échange de message par MPI (Message Passing Interface) sont ajoutées au code. Ensuite, l'amélioration de l'extensibilité des approches multidomaines par l'ajout d'une échelle macroscopique est testée. Enfin, dans la perspective d'un dialogue entre modèles discret (échelle microscopique) et continu (échelle macroscopique), une version enrichie de la méthode GSNL-DD (Gauss Seidel Non Linéaire en Décomposition de domaine) est proposée. L'accélération de convergence attendue est ensuite étudiée théoriquement sur des exemples de taille réduite, avant quelques tests sur échantillons plus conséquents.

Industrial demand for numerical simulation of granular media is increasing for large systems. The case of interactions between grains such as unilateral contact with friction involves additional difficulties to these simulations. This study investigates a domain decomposition approach. The sub-structuration methods were originally developed for continuous media usually discretized by finite elements for solid mechanics. The LMGC90 platform (software to manage contact with distinct elements) provides a framework for the implementation of algorithms. Thus, domain decomposition algorithms, based on the LArge Time INcrement and Non Linear Gauss Seidel methods, ans suited to a granular problem are defined, implemented and compared. To exploit the potential for parallel computing of the aforementioned methods, the exchanging messages with MPI (Message Passing Interface) is added to the code. Then, the improvement of the scalability of multi-domain approaches through the addition of a macroscopic scale is tested. Finally, in order to implement a dialogue between the discrete (microscopic scale) and continuous (macroscopic scale) models, an enhanced version of the NLGS-DD method (Non Linear Gauss Seidel with domain decomposition) is proposed. The expected acceleration of the convergence is studied theoretically on reduced-size samples, prior to performing some tests on larger samples.

Advisors/Committee Members: Alart, Pierre (thesis director), Dureisseix, David (thesis director).

Subjects/Keywords: Dynamique des sytèmes discrets; Décomposition de domaine; Numérique; Dynamic discrete systems; Domain decomposition; Numerical

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Iceta, D. (2010). Simulation numérique de la dynamique des systèmes discrets par décomposition de domaine et application aux milieux granulaires : Numerical simulation of dynamic discrete systems with domain decomposition and application to granular media. (Doctoral Dissertation). Université Montpellier II. Retrieved from http://www.theses.fr/2010MON20056

Chicago Manual of Style (16^th Edition):

Iceta, Damien. “Simulation numérique de la dynamique des systèmes discrets par décomposition de domaine et application aux milieux granulaires : Numerical simulation of dynamic discrete systems with domain decomposition and application to granular media.” 2010. Doctoral Dissertation, Université Montpellier II. Accessed February 27, 2021. http://www.theses.fr/2010MON20056.

MLA Handbook (7^th Edition):

Iceta, Damien. “Simulation numérique de la dynamique des systèmes discrets par décomposition de domaine et application aux milieux granulaires : Numerical simulation of dynamic discrete systems with domain decomposition and application to granular media.” 2010. Web. 27 Feb 2021.

Vancouver:

Iceta D. Simulation numérique de la dynamique des systèmes discrets par décomposition de domaine et application aux milieux granulaires : Numerical simulation of dynamic discrete systems with domain decomposition and application to granular media. [Internet] [Doctoral dissertation]. Université Montpellier II; 2010. [cited 2021 Feb 27]. Available from: http://www.theses.fr/2010MON20056.

Council of Science Editors:

Iceta D. Simulation numérique de la dynamique des systèmes discrets par décomposition de domaine et application aux milieux granulaires : Numerical simulation of dynamic discrete systems with domain decomposition and application to granular media. [Doctoral Dissertation]. Université Montpellier II; 2010. Available from: http://www.theses.fr/2010MON20056

Delft University of Technology

30. Leenders, Sjoerd (author). Numerical modelling of the migration direction of offshore sand waves using Delft3D: Including underlying seabed topography.

Degree: 2018, Delft University of Technology

URL: http://resolver.tudelft.nl/uuid:ae051d49-e639-460f-ba92-7305857ba592

► The growth of the offshore wind industry results in intensive usage of the sandy seabed in the North Sea, currently and in the coming decades.… (more)

▼ The growth of the offshore wind industry results in intensive usage of the sandy seabed in the North Sea, currently and in the coming decades. Large-scale bed forms are present in shallow seas with sandy beds such as the North Sea. The most dynamic bed forms are sand waves. Due to their dynamic behaviour, sand waves can interact within offshore human developments and together with their dimensions pose a threat; e.g. decrease in navigation depth, exposure of submarine cables, interaction with foundations of offshore wind turbines and destabilization of bed protections. A thorough understanding of the dynamics can result in less risks for the offshore wind sector and therefore bring down the levelized cost of electricity from offshore wind. Currently, sand wave field dynamics are investigated by data-driven analyses. These analyses are based on seabed surveys over preferable more than 10 years and are considered most reliable at the moment. However, these surveys are very costly and/or often not available. Complex numerical models may provide an approach to analyse sand wave dynamics in a cost and time efficient way, though two aspects have to be considered. Not all relevant processes regarding sand wave dynamics are yet understood. Furthermore, due to the large scale of sand wave fields in combination with the fine grid resolution required to model sand waves, large computational efforts form a difficulty for numerical modelling of sand wave fields. Previous numerical studies focused on reproducing the length and height of sand waves. The migration direction is the next step towards the full prediction of sand wave fields and the subject of this research. Recent data-driven analyses showed migration directions of sand waves in opposite direction over small spatial scale, possibly related to underlying seabed topography. Understanding the governing processes of the migration direction of sand waves including underlying seabed topography is the focus of this research using the numerical process-based model Delft3D. To this end, an idealized model is used in which underlying seabed topography (tidal sand bank) is included. For a symmetrical tidal velocity signal, it is shown that the presence of the tidal sand bank influences the hydrodynamics on the scale of sand waves. Horizontal tide-averaged flow towards the top of the tidal sand bank on both flanks is observed. This results in sediment transports and migration directions on both flanks of the tidal sand bank towards the top of the tidal sand bank. The horizontal tide-averaged flow pattern around the tidal sand bank is disturbed by the inclusion of a residual current. Sand wave migration on both flanks in the direction of the residual current is the result. Including the S4-tide constituent does not disturb the tide-averaged horizontal flow pattern around the tidal sand bank. However, the asymmetry of the tidal velocity signal enhances migration in the direction of the asymmetry. Finally, it is shown that also for a more realistic model the… Advisors/Committee Members: Aarninkhof, Stefan (mentor), Zijlema, Marcel (mentor), Walstra, Dirk-Jan (mentor), Borsje, Bas W. (mentor), Schouten, Jan-Joost (mentor), Hoekstra, R (mentor), Delft University of Technology (degree granting institution).

Subjects/Keywords: Sand waves; Tidal sand bank; Numerical Modelling; Domain Decomposition; North Sea; Delft3D

Record Details Similar Records Cite « Share

❌

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

APA (6^th Edition):

Leenders, S. (. (2018). Numerical modelling of the migration direction of offshore sand waves using Delft3D: Including underlying seabed topography. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:ae051d49-e639-460f-ba92-7305857ba592

Chicago Manual of Style (16^th Edition):

Leenders, Sjoerd (author). “Numerical modelling of the migration direction of offshore sand waves using Delft3D: Including underlying seabed topography.” 2018. Masters Thesis, Delft University of Technology. Accessed February 27, 2021. http://resolver.tudelft.nl/uuid:ae051d49-e639-460f-ba92-7305857ba592.

MLA Handbook (7^th Edition):

Leenders, Sjoerd (author). “Numerical modelling of the migration direction of offshore sand waves using Delft3D: Including underlying seabed topography.” 2018. Web. 27 Feb 2021.

Vancouver:

Leenders S(. Numerical modelling of the migration direction of offshore sand waves using Delft3D: Including underlying seabed topography. [Internet] [Masters thesis]. Delft University of Technology; 2018. [cited 2021 Feb 27]. Available from: http://resolver.tudelft.nl/uuid:ae051d49-e639-460f-ba92-7305857ba592.

Council of Science Editors:

Leenders S(. Numerical modelling of the migration direction of offshore sand waves using Delft3D: Including underlying seabed topography. [Masters Thesis]. Delft University of Technology; 2018. Available from: http://resolver.tudelft.nl/uuid:ae051d49-e639-460f-ba92-7305857ba592

		in
And / Or
		in
And / Or
		in
And / Or
		in

Open Access Theses and Dissertations