Sökning: "weak initial conditions"

Visar resultat 1 - 5 av 23 avhandlingar innehållade orden weak initial conditions.

  1. 1. High order summation-by-parts methods in time and space

    Författare :Tomas Lundquist; Jan Nordström; Peter Eliasson; David A. Kopriva; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; summation-by-parts; time integration; stiff problems; weak initial conditions; high order methods; simultaneous-approximation-term; finite difference; discontinuous Galerkin; spectral methods; conservation; energy stability; complex geometries; non-conforming grid interfaces; interpolation;

    Sammanfattning : This thesis develops the methodology for solving initial boundary value problems with the use of summation-by-parts discretizations. The combination of high orders of accuracy and a systematic approach to construct provably stable boundary and interface procedures makes this methodology especially suitable for scientific computations with high demands on efficiency and robustness. LÄS MER

  3. 2. Random iteration of isometries

    Författare :Markus Ådahl; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Mathematics; iterated function system; isometry; central limit theorem; weak invariance principle; law of the iterated logarithm; random walk; MATEMATIK; MATHEMATICS; MATEMATIK; Mathematics; matematik;

    Sammanfattning : This thesis consists of four papers, all concerning random iteration of isometries. The papers are:I. Ambroladze A, Ådahl M, Random iteration of isometries in unbounded metric spaces. Nonlinearity 16 (2003) 1107-1117. LÄS MER

  4. 3. Stability, dual consistency and conservation of summation-by-parts formulations for multiphysics problems

    Författare :Fatemeh Ghasemi Zinatabadi; Jan Nordström; Thomas Hagstrom; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : In this thesis, we consider the numerical solution of initial boundary value problems (IBVPs). Boundary and interface conditions are derived such that the IBVP under consideration is well-posed. We also study the dual problem and the related dual boundary/interface conditions. LÄS MER

  5. 4. High order summation-by-parts based approximations for discontinuous and nonlinear problems

    Författare :Cristina La Cognata; Jan Nordström; Sara Zahedi; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : Numerical approximations using high order finite differences on summation-byparts (SBP) form are investigated for discontinuous and fully nonlinear systems of partial differential equations. Stability and conservation properties of the approximations are obtained through a weak imposition of interface and boundary conditions with the simultaneous-approximation-term (SAT) technique. LÄS MER

  7. 5. Stable and High-Order Finite Difference Methods for Multiphysics Flow Problems

    Författare :Jens Berg; Jan Nordström; Per Lötstedt; David Zingg; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Summation-by-parts; Simultaneous Approximation Term; Stability; High-order accuracy; Finite difference methods; Dual consistency; Beräkningsvetenskap med inriktning mot numerisk analys; Scientific Computing with specialization in Numerical Analysis;

    Sammanfattning : Partial differential equations (PDEs) are used to model various phenomena in nature and society, ranging from the motion of fluids and electromagnetic waves to the stock market and traffic jams. There are many methods for numerically approximating solutions to PDEs. LÄS MER