Search for dissertations about: "natural convection boundary layer"

Showing result 11 - 15 of 24 swedish dissertations containing the words natural convection boundary layer.

  2. 11. CFD Study of Molten Pool Convection in a Reactor Vessel during a Severe Accident

    Author : Boshen Bian; Walter Villanueva; Sevostian Bechta; Weimin Ma; Shuisheng He; KTH; []
    Keywords : Severe accident; Corium; Natural convection; Turbulence; Scalability; Direct numerical simulation DNS .; Svåra haverier; härdsmälta; naturlig konvektion; turbulens; skalbarhet; direkt numerisk simulering DNS .; Physics; Fysik;

    Abstract : During severe accidents in nuclear reactors, the core and internal structures can melt down and relocate into the reactor pressure vessel (RPV) lower head (LH) forming there a stratified molten corium pool. The pool generally consists of superheated oxidic and metallic liquid layers imposing thermo-mechanical loads on the RPV wall. READ MORE

  4. 12. Modelling of Turbulent Flow and Heat Transfer for Building Ventilation

    Author : Peng Shia-Hui; Chalmers tekniska högskola; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; large eddy simulation; turbulent buoyant convection; ventilation performance assessment; purging flow rate; SGS modelling; ventilation flow; stochastic Markov chain model; turbulence modelling; LRN k-w model; two-equation models; building ventilation; transfer probability; transition regime; modified SGS buoyancy model; energy backscatter;

    Abstract : This thesis contributes to studies on the assessment of building ventilation performance and the development of turbulence models accounting for Low-Reynolds-number (LRN) effects and buoyant convection with heat transfer. Assessments of building ventilation performance are discussed with respect to indoor air distribution and passive contaminant dispersion. READ MORE

  5. 13. Pressure driven instabilities in the reversed-field pinch : numerical and theoretical studies

    Author : Ahmed Akram Mirza; Jan Scheffel; Roberto Paccagnella; KTH; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Fusion plasma; thermonuclear; Reversed-field pinch; resistive MHD; resistive g modes; thermal conduction; the boundary value theory;

    Abstract : According to classical linearized resistive magnetohydrodynamics theory, pressuredriven modes are unstable in the reversed-field pinch (RFP) due to unfavorable magnetic field line curvature. The result is based on the assumption of an adiabatic energy equation where anisotropic thermal conduction effects are ignored as compared to convection and compression. READ MORE

  6. 14. Homogenization of elliptic equations in thin cylinders and related qualitative problems

    Author : Iryna Pankratova; Nils Svanstedt; Luleå tekniska universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Mathematics; Matematik;

    Abstract : The thesis consists of four closely related papers (A, B, C and D). Paper A concerns the study of the behaviour at infinity of solutions to second order elliptic equation with first order terms stated in a half-cylinder. READ MORE

  7. 15. Crystallization and Differentiation Processes in the Thin Layered Alkali Gabbroic Intrusions of the Ulvö Gabbro Complex, Central Sweden

    Author : Johan Hogmalm; Göteborgs universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; layered intrusion; fractional crystallization; modal layering; in situ crystallization; Ulvö; saucer-shaped sill; post-cumulus; LA ICP-MS;

    Abstract : Fractional crystallization of magma is a commonly invoked mechanism for chemical differentiation in systems that range from volcanoes to entire planets. However, the processes that control separation of crystals and liquids in natural systems remain controversial, since the dynamics of crystallizing magma chambers cannot be studied directly. READ MORE