Sökning: "Domain perturbations"

Visar resultat 1 - 5 av 28 avhandlingar innehållade orden Domain perturbations.

  1. 1. Neutronics in reactors with propagating perturbations

    Författare :Anders Jonsson; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; one-group theory; Green s function; Molten Salt Reactors; two-group theory; neutron noise; propagating perturbations;

    Sammanfattning : This thesis contains several studies of the properties of neutron noise, primarily in Molten Salt Reactors and other reactors with propagating perturbations. Both one- and two-group diffusion theory are employed to investigate the differences that arise from the movement of the fuel. LÄS MER

  3. 2. A Linearized Navier-Stokes Equations Methodology for Aeroacoustic and Thermoacoustic Simulations

    Författare :Wei Na; Susann Boij; Gunilla Efraimsson; Niklas Andersson; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Linearized Navier-Stokes Equations LNSE ; frequency domain; tube row heat exchanger; hybrid liner; thermoacoustic instabilities; entropy waves; Rijke-tube; nozzle; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : Aeroengine noise is one of the dominating noise sources in today’s aircraft. Reduction of the aeroengine noise is related to multiphysics phenomena, and that is subject to different mechanisms, e.g., the coupling between turbulence, flame and sound waves. LÄS MER

  4. 3. Investigation of a discrete ordinates method for neutron noise simulations in the frequency domain

    Författare :Huaiqian Yi; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Deterministic neutron transport; Neutron noise; Ray effects; Numerical acceleration; Discrete ordinates method;

    Sammanfattning : During normal operations of a nuclear reactor, neutron flux measurements show small fluctuations around mean values, the so-called neutron noise. These fluctuations may be driven by a variety of perturbations, e.g., mechanical vibrations of core components. LÄS MER

  5. 4. The Skorohod problem and weak approximation of stochastic differential equations in time-dependent domains

    Författare :Thomas Önskog; Kaj Nyström; Leif Persson; Johan Tysk; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Skorohod problem; weak approximation; time-dependent domain; stochastic differential equations; parabolic partial differential equations; oblique reflection; stopped diffusions; Euler scheme; adaptive methods; sensitivity analysis; financial derivatives; Greeks ; MATHEMATICS; MATEMATIK; Mathematics; matematik;

    Sammanfattning : This thesis consists of a summary and four scientific articles. All four articles consider various aspects of stochastic differential equations and the purpose of the summary is to provide an introduction to this subject and to supply the notions required in order to fully understand the articles. LÄS MER

  7. 5. Eulerian Numerical Study of the Sedimentation of Fibre Suspensions

    Författare :Feng Zhang; Anders Dahlkild; Fredrik Lundell; Staffan Lundström; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Fokker-Planck equation; particle fluid flow; suspension; instability;

    Sammanfattning :  Sedimenting suspensions exist in a varity of natural phenomena and industrial applications. It is already observed in experiments that the dilute fibre suspensions experience a hydrodynamics instability under gravity at low Reynolds numbers. Initially well-mixed suspensions become inhomogeneous and anisotropic due to this instability. LÄS MER