Sökning: "Saddle point problems"

Hittade 5 avhandlingar innehållade orden Saddle point problems.

  1. 1. Ghosts and machines regularized variational methods for interactive simulations of multibodies with dry frictional contacts

    Detta är en avhandling från Umeå : Datavetenskap

    Författare :Claude Lacoursière; Umeå universitet.; [2007]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Discrete mechanics; Variational method; Contact problems; Impacts; Least action principle; Saddle point problems; Lagrange Multipliers; Constrained systems; Multibody Systems; Numerical regularization; Constraint realization; Constraint stabilization; Dry friction; Differential Algebraic Equations; Nonsmooth problems; Linear Complementarity; Quaternion algebra; Numerical linear algebra; Physics modeling; Interactive simulation; Numerical stability; Rigid body dynamics; Dissipative systems; NATURAL SCIENCES Physics Other physics Computational physics; NATURVETENSKAP Fysik Övrig fysik Beräkningsfysik;

    Sammanfattning : A time-discrete formulation of the variational principle of mechanics is used to provide a consistent theoretical framework for the construction and analysis of low order integration methods. These are applied to mechanical systems subject to mixed constraints and dry frictional contacts and impacts---machines. LÄS MER

  2. 2. Computational Techniques for Coupled Flow-Transport Problems

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Martin Kronbichler; Uppsala universitet.; Uppsala universitet.; [2011]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Finite element method; saddle point systems; two-phase flow; level set method; phase field method; stabilization; contact line dynamics; Beräkningsvetenskap med inriktning mot numerisk analys; Scientific Computing with specialization in Numerical Analysis;

    Sammanfattning : This thesis presents numerical techniques for solving problems of incompressible flow coupled to scalar transport equations using finite element discretizations in space. The two applications considered in this thesis are multi-phase flow, modeled by level set or phase field methods, and planetary mantle convection based on the Boussinesq approximation. LÄS MER

  3. 3. Computational Homogenization of Transient Problems - Application to Porous Media

    Detta är en avhandling från Chalmers University of Technology

    Författare :Fang Su; Chalmers tekniska högskola.; Chalmers University of Technology.; [2012]
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; homogenization; FE2; Representative Volume Element RVE ; consolidation;

    Sammanfattning : This thesis is devoted to the development and analysis of a homogenization-based computational strategy for simulating the transient and nonlinear coupled consolidation problem in micro-heterogeneous porous media. A variational framework and the pertinent finite element (FE) strategy, based on a generalized macro-homogeneity condition, are proposed for the spatial homogenization of a class of transient problems, whereby the classical assumption of first order homogenization is adopted. LÄS MER

  4. 4. Robust Preconditioners Based on the Finite Element Framework

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Erik Bängtsson; Uppsala universitet.; Uppsala universitet.; [2007]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; FEM; iterative solution method; algebraic multilevel preconditioner; sparse approximate inverse; block preconditioner; Schur complement approximation; nonsymmetric saddle point matrix; isostatic glacial adjustment; pre-stress advection; elasticity; viscoelasticity; in compressible solid; ABAQUS; BEM DDM; Scientific Computing; Beräkningsvetenskap;

    Sammanfattning : Robust preconditioners on block-triangular and block-factorized form for three types of linear systems of two-by-two block form are studied in this thesis.The first type of linear systems, which are dense, arise from a boundary element type of discretization of crack propagation problems. LÄS MER

  5. 5. Robust preconditioning methods for algebraic problems, arising in multi-phase flow models

    Detta är en avhandling från Uppsala University

    Författare :Xin He; Uppsala universitet.; Uppsala universitet.; [2011]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Scientific Computing; Beräkningsvetenskap;

    Sammanfattning : The aim of the project is to construct, analyse and implement fast and reliable numerical solution methods to simulate multi-phase flow, modeled by a coupled system consisting of the time-dependent Cahn-Hilliard and incompressible Navier-Stokes equations with variable viscosity and variable density. This thesis mainly discusses the efficient solution methods for the latter equations aiming at constructing preconditioners, which are numerically and computationally efficient, and robust with respect to various problem, discretization and method parameters. LÄS MER