Sökning: "Reynolds stress closures"

Hittade 5 avhandlingar innehållade orden Reynolds stress closures.

  1. 1. An Experimental Study of Reynolds Stress Closures in Shear Free and Weakly Sheared Turbulence

    Författare :Dag Aronson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; turbulence modelling; dissipation measurements; Reynolds stress closures; isotropic turbulence; anisotropic dissipation rate tensor; hot-wire anemometry; wall proximity effects; pressure strain rate correlations;

    Sammanfattning : The objective of this thesis work is to obtain data enabling evaluation of closure hypotheses used in the Reynolds stress transport (RST) equations. Special attention has been devoted to studies of flow fields with shear free and weakly sheared turbulence. LÄS MER

  3. 2. Anisotropy-resolving subgrid-scale modelling using explicit algebraic closures for large eddy simulation

    Författare :Amin Rasam; Arne Johansson; Bernard Geurts; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Turbulence; large eddy simulation; explicit algebraic subgridscale model; passive scalar; stochastic modelling; periodic hill flow; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : The present thesis deals with the development and performance analysis ofanisotropy-resolving models for the small, unresolved scales (”sub-grid scales”,SGS) in large eddy simulation (LES). The models are characterised by a descriptionof anisotropy by use of explicit algebraic models for both the subgridscale(SGS) stress tensor (EASSM) and SGS scalar flux vector (EASSFM). LÄS MER

  4. 3. Modeling of magnetohydrodynamic turbulence

    Författare :Ola Widlund; KTH; []
    Nyckelord :turbulence model; magnetohydrodynamic; mhd; magnetohydrodynamic turbulence; computational fluid dynamics; continuous casting;

    Sammanfattning : Conventional one-point turbulence closures have beenextended with an additional transported scalar for modeling ofmagnetohydrodynamic (MHD) turbulence. The new scalar, α ,captures the length scale anisotropy and tendency towardstwo-dimensionality, which is characteristic feature of MHDturbulence, and allows accurate modeling of the Jouledissipation of turbulence. LÄS MER

  5. 4. A numerical investigation of energy conversions in geophysical boundary layers

    Författare :Patrik Andreasson; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Vattenteknik; Water Resources Engineering;

    Sammanfattning : The detailed energy conversions in turbulent geophysical boundary layers are examined and quantified. The governing transport equations are solved by utilizing turbulence modelling. Different turbulence closures have been adopted for the boundary layers examined. LÄS MER

  7. 5. Numerical Simulations of Cooling Concepts Related to Gas Turbine Combustors

    Författare :Andreas Abdon; Värmeöverföring; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Motors and propulsion systems; plasma; combustor; gas turbine; cooling; numerical simulations; turbulence; ribs; impingement; Gases; fluid dynamics; plasmas; fluiddynamik; Gaser; Motorer; framdrivningssystem; Thermal engineering; applied thermodynamics; Termisk teknik; termodynamik;

    Sammanfattning : The mean by which a gas turbine combustor is cooled is of major importance for the efficiency and emission performance of the machine. The trends of increasing top cycle temperature and leaner combustion have also been accompanied by a need of efficient use of the cooling air. LÄS MER