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Showing result 1 - 5 of 23 swedish dissertations matching the above criteria.

  2. 1. Runge-Kutta Solution of Initial Value Problems: Methods, Algorithms and Implementation

    Author : Hans Olsson; Institutionen för datavetenskap; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Computer science; stiffness; software; computational process; differential algebraic equations; ordinary differential equations; Runge-Kutta; initial value problems; time-stepping; system; kontroll; numerisk analys; Datalogi; control; numerical analysis; systems;

    Abstract : The last decades have seen a strongly increasing use of computers for modeling larger and more complex systems. This has been made possible by a combination of increasing computer power and easy-to-use graphical modeling environments and libraries of components. READ MORE

  4. 2. Runge–Kutta Time Step Selection for Flow Problems

    Author : Karl Hörnell; Per Lötstedt; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Runge-Kutta; stepsize selection; optimization; flow problems; numerical analysis; Numerical Analysis; Numerisk analys;

    Abstract : Optimality is studied for Runge-Kutta iteration for solving steady-state and time dependent flow problems. For the former type an algorithm for determining locally optimal time steps is developed, based on the fact that the squared norm of the residual produced by an m-stage scheme is a 2m-degree polynomial, the coefficients of which can be computed from scalar products of Krylov subspace vectors. READ MORE

  5. 3. Numerical Simulation of Turbulent Flows for Turbine Blade Heat Transfer Applications

    Author : Jonas Larsson; Chalmers tekniska högskola; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; k-.omega.; k-.epsilon.; explicit Runge-Kutta; finite volume; turbine; numerical method; non-linear; Navier-Stokes; supersonic; two-equation; external heat transfer; stagnation flow; two-dimensional; transition; low-Reynolds; turbulence model; impulse blade;

    Abstract : Turbine blade heat transfer is an important engineering problem characterized by complex flow fields and high turbulence levels. This thesis is focused on using a full Navier-Stokes solver with two-equation eddy-viscosity models to predict external heat-transfer in single-stage, linear, two-dimensional uncooled turbine cascades. READ MORE

  6. 4. Preconditioning for block matrices with square blocks

    Author : Ivo Dravins; Maya Neytcheva; Svetozar Margenov; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; preconditioning; block preconditioning; PDE-constrained optimization; Implicit Runge-Kutta methods; Beräkningsvetenskap med inriktning mot numerisk analys; Scientific Computing with specialization in Numerical Analysis;

    Abstract : Linear systems of equations appear in one way or another in almost every scientific and engineering problem. They are so ubiquitous that, in addition to solving linear problems, also non-linear problems are typically reduced to a sequence of linear ones. READ MORE

  7. 5. Geometric discretization for incompressible magnetohydrodynamics on the sphere

    Author : Michael Roop; Chalmers tekniska högskola; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Lie-Poisson structure; magnetohydrodynamics; Hamiltonian dynamics; magnetic extension; Casimirs; symplectic Runge-Kutta integrators;

    Abstract : Many physical processes are modelled by partial differential equations (PDE), and their efficient discretization is still a challenging problem and an actively developing field. An important class of models arising in mathematical physics represents PDEs formulated in terms of a Lie-Poisson structure on the dual of infinite-dimensional Lie algebras, such as the Lie algebra of vector fields. READ MORE