Sökning: "nonsymmetric saddle point matrix"

Hittade 3 avhandlingar innehållade orden nonsymmetric saddle point matrix.

  1. 1. Analysis and Implementation of Preconditioners for Prestressed Elasticity Problems : Advances and Enhancements

    Författare :Ali Dorostkar; Maya Neytcheva; Thomas Huckle; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; FEM; Saddle point matrix; Preconditioning; Schur complement; Generalized Locally Toeplitz; Prestressed elasticity; Scientific Computing; Beräkningsvetenskap;

    Sammanfattning : In this work, prestressed elasticity problem as a model of the so-called glacial isostatic adjustment (GIA) process is studied. The model problem is described by a set of partial differential equations (PDE) and discretized with a mixed finite element (FE) formulation. LÄS MER

  3. 2. Robust Preconditioners Based on the Finite Element Framework

    Författare :Erik Bängtsson; Maya Neytcheva; Per Lötstedt; Svetozar Margenov; Uppsala universitet; []
    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

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

    Författare :Xin He; Maya Neytcheva; Uppsala universitet; []
    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